CA2141459A1 - Controlled release implants - Google Patents
Controlled release implantsInfo
- Publication number
- CA2141459A1 CA2141459A1 CA002141459A CA2141459A CA2141459A1 CA 2141459 A1 CA2141459 A1 CA 2141459A1 CA 002141459 A CA002141459 A CA 002141459A CA 2141459 A CA2141459 A CA 2141459A CA 2141459 A1 CA2141459 A1 CA 2141459A1
- Authority
- CA
- Canada
- Prior art keywords
- coating
- pulse release
- outer coating
- hydrogel
- release implant
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K9/00—Medicinal preparations characterised by special physical form
- A61K9/0012—Galenical forms characterised by the site of application
- A61K9/0019—Injectable compositions; Intramuscular, intravenous, arterial, subcutaneous administration; Compositions to be administered through the skin in an invasive manner
- A61K9/0024—Solid, semi-solid or solidifying implants, which are implanted or injected in body tissue
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- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Neurosurgery (AREA)
- Dermatology (AREA)
- Chemical & Material Sciences (AREA)
- Medicinal Chemistry (AREA)
- Pharmacology & Pharmacy (AREA)
- Epidemiology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Medicinal Preparation (AREA)
Abstract
A pulse release implant comprising: an axial biodegradable core; a first concentric layer comprising dehydrated hydrogel containing an active ingredient; and an outer coating, said outer coating being removable by the environment in which the im-plant will reside after administration. A process of preparing a pulse release implant including the steps of: coating an axially disposed biodegradable core material with a hydrogel containing an active ingredient to form a concentric coating; separating the coating into discrete segments disposed along the core material; dehydrating the hydrogel; coating the discrete segments with an outer coating, said outer coating being removable by the environment in which the implant will reside after administration; and removing the exposed core material to obtain the pulse release implants.
Description
~ 94/03159 21~1 g 5 9 pcr/Au93/oo392 CONTROLIED RELEASE IMPLANTS
FTF.T n OF THF TNVFNTION
S This invention relates to imrl~ntc CQI~t~ g active ingrerlient~ especially drugs or veterinary products suitable for ~l...i..i~l. ation to h1lm~nc and ~nim~lc in which the active ingredient is required to be ~ ed in a pulsatile release profile.
Prior art imp1~ntc are typically of the reservoir type and usually co~t~in a single 10 active ingredient and provide the c~..li..i~ous release of the active in a zero or first order mode of release kinetiec Present metho~lc of m~king these prior art imp1~ntc use basically two approaches, viz, (i) tabletting; and (ii) melt proceccin~. Re~ece..t~tives of these approaches are 15 described as follows:
(i) T~h1ettin~ (Tnt.orn~tion~l P~t~nt ~li-~tion No. P(~T/AIJ87/00139) A water incolllhle ~oYririçnt (eg, r~ lm lJhos~.h~te) is thoroughly mixed with a bioactive agent such as a ~rotei~ or pepti-le in an amount sllffieient to givethe required dosage unit of active ingredient in the final product. The bioactive agent is usually in the form of a so1lltion or dispersion or powder to f~ lit~te miYing. A water so1nhle ~Y~ipi~nt (eg, lactose), if used, is then added, together with the other desired additives, eg, a lubricating agent such as m~ s;~.~.. stearate, and ixed to form a homogeneous dry powder. The powder is then co~ essed into a tablet of the desired size and shape. The co~essed tablet is then coated in a pan coater by spraying with a solution or dispersion of the ro~ting material in an amount sufficient to give impl~nt~
with the reguired co~ting thickn-occ In an alternative coating method known as Wurster coating, the tablet is coated in a flllirli7e~ bed system.
Wo 94/03159 PCr/AU93/00392 ~
FTF.T n OF THF TNVFNTION
S This invention relates to imrl~ntc CQI~t~ g active ingrerlient~ especially drugs or veterinary products suitable for ~l...i..i~l. ation to h1lm~nc and ~nim~lc in which the active ingredient is required to be ~ ed in a pulsatile release profile.
Prior art imp1~ntc are typically of the reservoir type and usually co~t~in a single 10 active ingredient and provide the c~..li..i~ous release of the active in a zero or first order mode of release kinetiec Present metho~lc of m~king these prior art imp1~ntc use basically two approaches, viz, (i) tabletting; and (ii) melt proceccin~. Re~ece..t~tives of these approaches are 15 described as follows:
(i) T~h1ettin~ (Tnt.orn~tion~l P~t~nt ~li-~tion No. P(~T/AIJ87/00139) A water incolllhle ~oYririçnt (eg, r~ lm lJhos~.h~te) is thoroughly mixed with a bioactive agent such as a ~rotei~ or pepti-le in an amount sllffieient to givethe required dosage unit of active ingredient in the final product. The bioactive agent is usually in the form of a so1lltion or dispersion or powder to f~ lit~te miYing. A water so1nhle ~Y~ipi~nt (eg, lactose), if used, is then added, together with the other desired additives, eg, a lubricating agent such as m~ s;~.~.. stearate, and ixed to form a homogeneous dry powder. The powder is then co~ essed into a tablet of the desired size and shape. The co~essed tablet is then coated in a pan coater by spraying with a solution or dispersion of the ro~ting material in an amount sufficient to give impl~nt~
with the reguired co~ting thickn-occ In an alternative coating method known as Wurster coating, the tablet is coated in a flllirli7e~ bed system.
Wo 94/03159 PCr/AU93/00392 ~
(ii) Melt Pror~ccir~ ("A sllct~in~-l rele~ce Iverme~tin impl~nt for livestork pect control" by J ~ll~n Miller, R ) nrllmmonrl n n C~ehler in "Contrnlled Rel~ce 1 )~liv~ry ~yst~mc" ed. Theodore ~ Rncem~n ~n~ ~ 7. M~ncdorf, 1983, M~rcel-nekk~r; Ch~pter 15, pp ??~-?.~6) An imrl~nt cont~ining 20% Ivermectinwas form~ te-l by dissolving technic~l Ivermectin in a melt of polyethylene glycol (PEC~) (MW 15,000 - 20,000).
The solution was then drawn by vacuum into a 3 mm internal diameter Teflon tube and allowed to cool. Upon cooling the r~cl~lt~nt solid rod (3mm ~i~m~ter) was removed and trimmed to the desired weight of 400 mg.
Tmrl~nt products of this type are solid cylindrical rods of varying length and diameter and can have shapes ranging from flat discs to fine needles. This type of imrl~nt is useful where a prolonged c~ nllc supply of the drug is required.
The pan co~ting and Wurster coating methn-lc involve sllhst~nti~l contact between the imrl~ntc being coated. During the drying process, the coating gets sticky reslllting in impl~ntc stirking together or lwi.~.;,.g". It has been attempted to .~.r~e this problem by the ~rl~lition of additives and mo-lifi~rs in the coating.
20 When the impl~ntc are to be used for ~ dLion to hnm~nc or ~nim~lc, the additives which may be used are limited to those a~ al~ 'eS cleared for regulatory use. Polyester Cc~tin~c~ for toY~mrl~ have been cleared for re~ tory u e howeverthece ~lesen~ a particular problem in the pan coating method due to a&esion of the partide_ during the drying process. In ~rlrlitinn pinholes and other discontinnititos 25 can for_ in the outer coat during the drying process.
It would be desirable to avoid mutual contact of the impl~ntc during the drying process and to be able to control the drying process to avoid the formation of pinhnles and ~ co~ ;es There are freguent ci~ "~ n~es where impl~ntc are re~uired to provide a pulsatile release of an active ingredient. An example of such circurnstances is the so-called ~ W O 94/031~9 214 I 4 5 9 PC~r/A U93/00392 "one shot vaccine" concept. V~c~in~tion has been used to protect hllm~n~ and ~nim~lc against bacterial and viral infectious ~ice~c~os. In the case of vaccines prepared in the form of killed su~;~ions of bacteria or viruses, or in the form of conjugated tnYni~ls, repeated injections at specific ti_e intervals are required in order 5 for the v~crin~tion to effect adequate levels of i"""""ological res~llse. These intervals may typically range from a few weeks to several mont_s. Due to prevailing epiclçmiological, social, ec~"o",ic ~ce-~ibility, human tc~lA.\~t nt~l~ or simply collve,.ience reasons, it is highly desirable that effective protection against ~i~e~ces can be obtained with single injectionc In order to make this possible the one shot 10 v~ n~s have to release the actives at the fc~ el intervals, i.e. in a pulsatile mode, in the le~ ed profile, i.e. a "du~ ". A further applic ~tinn of the "one shot vaccine"
approach is a 6 month or 12 month contraceptive impl~nt or vaginal su~o~ito~
which delivers the contracc~ hormones in a sllcce~;Q.. of pulses, the active ingredient in this applic~tinn not being a vaccine.
A further no.l ~accillc ~Y~mple relates to the need for delivery of reaction mi~ctures to sites of action, specific~lly the delivery of the la~;~u~rn~ ce thiocyanate enzyme substrate re~tion system to the hin~ t~ of piglets in the control of diarrhoea.
La~;~o~.r~ e, coupled with a peroxide ge~ ~a~i~g ny~ e (eg, x~nthine and 20 x;-..lhi~.r nYirl~ce) CO~ SCN to SCNO, a very l~a;live and lethal ion for micro-Olg,...;~ . Pulse release terhnnlogy can be used to address the problem of rCi~r~
Constructing a delivery vehicle to meet these sorts of functional requirements 25 tlem~nfls a te~ hnology of m ~king co. . .p~ - 1 -. .ent~liced structures. The manufacturing process should ~,efelably be simpl~, v~ns~tile and ~m~n~hle to me( h~ni~tion and ~ llt-)m ~tic~n.
Although the most i ~ ~t attribute of a controlled release drug delivery device 30 is its capabilityto m~int~in a the.~ ;c~llyerr~ level of drug in an animal body over a srhedllled period of time, its adoption nltim~tely depends on the cost, co,lv~ n~e, and ease of its fabrication and ~.l...i..i~ation (1).
W O 94/03159 ~141 4 5 9 PC~r/A U93/00392 In terms of the ease and co..v.~..ien.-e of ~.~minictering these devices as imrl~ntc, shapes like sheets, films or hPmicpheres are generally impractical. However rods, nee~lles or cylinders are readily adapted for parenteral imrl~nt~tinn using a co~vGnlional hypodermic nPelle.
Pro.~llring eccentric shapes such as rods, n.-e.~lP~ ~r cylinders with the abovedescribed prior art methods, is also problematic. The pan coating and Wurster ro~tin~ methn ls are most ~mPn~hle to imrl~ntc of a generally rounded shape.
10 The applicant's cc,~l~-li.\g Appli.~tion PCI/AU93/00083 discloses a method ofmAkin~ imrl~ntc which are suitable for co..lillllous release of an active ingredient over a period of time which consist of a body member co".p,~ing a membrane forming a wall around a core matrix and co~l~ing material which is substantiallyiLIl~ViOUS to the active ingredient .-J~nt~inPc1 within the core matri~ The cylinder 15 is generally open ended, the active ingredient being rele~cecl directly through the open ends of the cylinder. In order to make an impl~nt suitable for pulsatile release using this terhni.lue, it is n~cpcc~ry to separately coat the open ends of the impl~nt This s~ate co~ting step is ~ clumsy, and time co.,~lmin~
20 A need accoldi~ exists for a simple and econnmi. ~l m~nllf~.-tllring process for imrl~ntc which can release bioactive materials and which can be readily adapted for comrl~Y in particular, pulsatile release of these materials.
AccoL.liLIgly, one aspect of the ~ se.~t invention cont~mrl~tPc a pulse release 25 imrl~nt com~ illg:
an axial biodegradable core;
a first concentric layer co~ g dehydrated hydrogel cont~ining an active ingredient; and an outer co~ting, said outer coating being removable by the environment in 30 which the imrl~nt will reside after ~I",i~ , ation.
--WO 94J03159 41 4 ~ 9 pcr/Aus3/oo392 In a further embodiment of the present invention there is provided a process of e~ lg a pulse-release impl~nt inrlnc~ing the steps of:
co~ting an axially tiicposecl biodegradable core material with a hydrogel cont~ining an active ingredient to form a conrentric coating;
S se~a,a~ing the coating into discrete se menn disposed along the core material;
dehy~ ~ing the h~l~ogel;
coating the discrete segm~ntc with an outer coating, said outer coating being removable by the ellvilo~ nt in which the imrl~nt will reside after ~rllni~ tion;
and removing the P~se~ core material to obtain the pulse release imp1~ntc The biodegradable core may be formed from any suitable material. Pl ~ fel ably the core is bioc~ tible. The core may be formecl from a string, suture or rod.
The term l~ vgel is uced in its ord~ art rec~p.-i~ed me~ninE of a watel-based three ~lim~ncion~l nonflowable amvl~hvus structure. The gel maybe created by ionic or hydrogen bond inter~innc. Hydrogels of particular mte.~ sl consist of a solution of a pvlymer in water which under controllable CO~ C can be made to adopt 20 either a fluid or semi-solid ~nfi~lration. This allows the hydrogel to be applied as a fluid to the core member and retain its shape as a semi-solid form. Methods toinduce the t~ ;ol- in~ e tell~ ul~ control or the use of cross-linking agents such as t~ lm ions. The te~la~u~ control ,llelllncl is suitable for gels such asagar and gelatine and the cross-linking metho~l is sllit~ble for hydrogels formed from 25 substances such as ~l in~te polymers.
In the ~rese~lt invention, a hydrogel in a fluid form is applied to the axial biodegradable core, a tr~ncition to a semi-solid state is in~ ec~ and the hydrogel is thereby immobilised. In this state, the hy-drogel may be cut and otherwise 30 maniplll~tecl When water is removed from the semi-solid form, a dehydrated hydrogel is form~.-l The dehy~ated hy~ogel forms a rigid solid which is suitablefor storage and h~n~11ing WO 94/03159 21. 41 ~5 9 PCI/AU93/00392 ~
Any suitable hydrogel may be used. F~mrles are gel~tine, agar, ~lginates~
carrageenan, gum gr~g~ nth, acacia, or corn starch. It may also be desirable to in~ le other components in the first concentric layer. F-~mrles are disintegrating agents such as corn starch, potato starch, alginic acid and the like and/or a lubricant S such as m~gnesillm stearate. Osmotic morlifi-ors such as sucrose and gl~1r~se may also be desirable. All such CO~ CIlLS, sho~iltl be subst~nti~lly pharmaceutically pure and non tc)x,c in the amounts employed and should be biocompatible and compatible with the active ingredient when used for human or animal use.
10 The active ingredient is typically a bioactive mc~lecllle and incl-1-les any native, synthetic or recombinant pharm~elltic~l agent or food additive or supplement in~ 1llclin~ antigens, antibodies, cytokines, growth promotants, hormones, cancer cell inhibitory moleclllP5 or agents, immllne stimlll~ntc or ~u~læc~ntc, anti-microbial agents inchl~tin~ antibiotics, anti-viral agents, vit~minc, minerals or inorganic or 15 organic nutrient~s. The active ingredient may ~~ ~c one type of bioactive molecule or may be a ~ ule of ~rr~e~ bioactive molecules. In a ~lefel~ed embodiment the active ingredient inclll~tes antigen~s from the clostridial family.
The outer ro~tin~ may be formed of any suitable bior~mratible substance. The 20 outer co~ting is generally meml~r~ous or polymeric and is sllhst~ntizllly illl~Cl vious to the active ingredient. The majority of the active material will be delivered or r~le~ced as a result of the removal of the outer co~ting ~...r~;..g the hrst concentric layer. F.~mple~s of suitable coating materials in~ e mo-iified starches, sugars, poly anhydrides, polyorthoecters, bioerodible polyc:,lcl:, and the polylacticlpolyglycolic 25 acid f~mily of polymers. Polylactic/polyglycolic acids are particularly suitable as they are widely commercially available v.~ith various degradation profiles and have regulatory clearance.
The co~ting may have a thickness of from typically lO~n to l,OOO,um depending on30 the app1ic~tion of the impl~nt and the permeability or degradability of the coating.
o 94/03159 ~! ~ 414 5 9 Pcr/Au93/oo392 Sli~ling The imrl~nt device may be in any suitable shape int lll~ine elongate, oval, round, ball, capsule, rod, needle, or cylinder shape. Conveniently, the shape is an elongate S cylindrical, rod or needle shape. In a most ~refe,lcd embodiment, the imrl~nt device is elongate and generally ~cal.
In the ~lucess of the present hl~ .~ion, an axially ~lisposed biodegradable corematerial is coated with a hydrogel Cb..~i"i,.g an actIve ingredient to form a 10 concentric co~ting~ .~m~ r clis~te gel se~n~ontc~ which remain supported by the biodegradable core can be created by cutting the outer concentric hydrogel layer in such a way that the biodegradable core remains intact and sliding the cut segment along the axially dis~osed biodegradable core so as to form a space between the discrete gel se~n~ntc This operationwill hereinafter be refe.l~ d to as the "cut/slide 15 operation".
The cut/slide operation may be ~,.;. r~" ...cd after the hydrogel has been dried and prior to co~tine hc.... ._r it is generally easier to ~.rulm the cut/slide operation on wet hydrogel. Ther~ rwe in the ~ocess of the l,ieseilt invention the separation and 20 dchy~llation steps may take place in either order. For ey~mrle the hydrogel may be dehydrated before se~ tion into discn te se~ ntc although it is preferred that the hydrogel is s_~atcd before dch~l~aliolL
The outer co~*n~ may be ~rplied in any suitable m~nn-or. For ~Y~mple, the outer 25 coa*ng may be applied by means of a mould, dipping, s~. aji,lg or by application via a "rod" or ' wic~".
The above cut/slide opera*on ù~reoll,es certain deffciencies of known prior art co~tin~ methods in that the problems of the impl~ntc st~ ng together during the 30 drying ploeess iS U~r~llle and the problem of pinholes and disco.~ ies in the- outer coat is alleviated as the drying process of the prese~t inven*on may be better controlled.
wo 94/03159 PCr/A~193/00392 ~
2~4145~ ' Once the outer coating has been applied, the exposed core material may be cut away rçsllltin~ in discrete pulse release impi~ntc.
The process of the present invention is readily adaptable for incorporation of heat S labile active ingreriisntc. It pl~esen~ few COllaLldiL~tS wlth respect to the choice of active ingredients; and it should be noted that by usl~g a biodegradable structural :~iU~ ul l, such as surgical suture, the central core does not need to be removed from the final imrl~nt product.
10 The present device also provides the basis on which further r~fin~m~nt or sophistil ~tinn of release can be effected. For in~n~ e by usirlg as the hydrogel layer bioerodible polyorthoester polymerc prepared by the reaction bet~veen 3,9-bis(ethylidene-2,4,8,10-tetrau~iro [s~s]-lln~lec~ne) and various ratios of trans-cyclohto~neclimethanol and 1~6-hey~n~linl (2), the production method can be readily 15 adopted for mass production of needle injectable imrl~ntc of ~,.til",nour agents such as 5 flu~o-~l acil for release in a time independent mode. Likewise, by using collagen poly (HEMA) ~ gel (1) as the .~ ~g ma~, needle injectable impl~ntc can be readily mass pro lllre~l for a variety of hydlu~hilic or hydrophobic active snhs~n~e with again a time in~lepPn~lent release mode.
The reciriçnt of the imrl~nt may be a hnm~n, livestûck animal inr l~ ing a rnmin~nt ~nim~l, e.g. a sheep, cow, horse, pig, goat or donkey, poultry, e.g. chicken, turkey, goose or game bird, a la~,olatc,ly test ~nim~l, e.g a rabbit, guinea pig or mouse, Co",~-Z "ion ~nim~l e.g. dog or ca~, or a wild animal in the captive or free state.
minictration of the imrl~nt may be by any co~vc;-lient means but is generally byinjection via the h~LldVenOIlS, i~L~d~-;lo~ l, intr~m-lcc-ll~r, sub-c~lt~n~ous or intradermal route. The device may also be surgically imrl~ntefl or imrl~ntecl by sub-surgical procedures such as during biopsy procedures. Devices such as these may aLo 30 be ~.l",i"i~ered by an oral route.
.
The amount of active ingredient used in a given imrl~nt will vary depending on the ~Wo 94/031S9 21~14 5 9 PCI/AU93/00392 '~ f;
_ 9 _ type of bioactive molecule, con~lition in the animal being treated and the presence or ~hsçnre of agonists to the active ingredient or ~nt~gonicts to the con-lition being treated. In general, an effective amount of active ingredient is employed meaning an amount effective to in~ln~t, stim~ te, promote or otherwise initi~te the imrnediately S intPn-ied result~
, ~
For tY~mp1e, if the active ingredient is an antigen, the effective amount is that required to stim~ te an imm1mr rt.~l-~c to tihe ~ntig~on Commonly, the active ingredient will be present in amounts ranging from a few micrograms to gram 10 quantities per imrl~nt The invention will be further described by r~relellce to the following non-limiting figures and ~ s I~ the figures:
Figure 1 is a part section~1, part srhtm~tir, cross section of an apparatus 15 suitable for ~ g imp1~nt cores by rhrmis~lly in-l11recl gelling.
Figure 2 is a part section~1, part srhtm~tir cross secti~ n of an apparatus s1~it~hle for ~ari~g imp1~nt cores by te~ldlule in-lurecl gelling.
Figure 3 is a srhrm~tic illu~Ll~Liol. of spray co~ti~ of hydrogel impl~ntc.
Figure 4 is a schematic illustration of rod co~ting solvent based polymer 20 co~ting app1ir~tion Figures 5 and 6 are graphs of dye release from 35% (pLa i.v. 1) to1l11ene rod coated gelatine core imr1~ntc; in vitro at PBS at pH 7.2, 37 C.
Tn~l~nt Y~ ;
Apparatus suitable for use in the method of the ~csellt invention varies depenrling whether the gel results from tG~lature or rh~-mic~1 effects. Figures 1 and 2 are30 part section~l~ part srhrm~tir cross sectionc of the a~ Lu~ for preparing imp1~nt cores. In one embo-limrnt i~lustrated in Figure 1 for rhrmir~11y in-i11refl gelling, the a~dld~us concictc of a dialy is tube "1" fitted over an upper end portion "2" and a WO 94/03159 ~ i PCr/AU93/00392 ~
2 1 ~ 9 lower end portion "3" and located in sealing engagement by wate:,~rwf rubber sealants "4" and "5". A ~u~ ing line forrneci of bioerodible core material "6" is m~int~ine~i under ten~ion by a spring steel bow "7". An inlet port "8" and bleeder hole "9" are provided respectively in the lower and upper end portions "2" and "3".
S An outer perforated mould "10" is provided to ~u~ l the dialysis tube "1" and allow the ingress of geliing reagents to the dialysis tub~. ~is outer perforated mould may be hinged to allow easy access to the dialysis tube.
In an alternative embodiment illustrated in Figure 2, s~lit~hl~ for te~ u~e 10 in~ ceci gelling, the dialysis tube "1" is repl~ced with a teflon tube "11" which may be in two longitllriin~l halves and the outer perforated mould "10" is replaced with a j~t~keteci te.n~e~-ature control member "12".
For structural stability of the gel during subsequent processing the gel structure is 15 held on the ~u~w ~ "6". For symmetry and ~ ~ the ~u~ "6" is centred using the upper and lower end portions "2" and "3". The ~u~ line "6" is kept taut using a device "7" made of spring steel r~os~mbling a bow. This device serves also as a handle to Lla~ the gel structure for the coll~..;Pnc~e and security of subsequent gel l~luce~ g, e.g. drying and co?tin~
Referring to Figures 1 and 2, a central su~ which forms the bioerodible core "6", e.g. a surgical suture, is p~citiontod at the radial centre in a cylindrical mould "1" or "11" using a~ ,yliate pocitirming guides. For water based polymeric matrices, the inner s~ e of the mould should be lined with material such as teflon to f~ilit~te 25 cast removal.
A temperature se~ ive impl~nt hydrogel layer or core matrix on the central ~ L
may be prepared in the following m~nner:
Insert the hol;"~ lly sectioneci teflon tube "11" into the j~rk.o.tecl temperature control member "12" with a~.. ,c;.n~t~ly 1.0 cm of the teflon tube protruding from one end of the glass tube.
2 Run the ~u~l l line "6" through the bottom end portion "3" and knot ~ W 0 94/031~9 ~ 1 4 1 ~ 5 9 PC~r/A U93/00392 on the external side of the end portion "3" to ensure the line does not pull through (see Step 9 below).
The solution was then drawn by vacuum into a 3 mm internal diameter Teflon tube and allowed to cool. Upon cooling the r~cl~lt~nt solid rod (3mm ~i~m~ter) was removed and trimmed to the desired weight of 400 mg.
Tmrl~nt products of this type are solid cylindrical rods of varying length and diameter and can have shapes ranging from flat discs to fine needles. This type of imrl~nt is useful where a prolonged c~ nllc supply of the drug is required.
The pan co~ting and Wurster coating methn-lc involve sllhst~nti~l contact between the imrl~ntc being coated. During the drying process, the coating gets sticky reslllting in impl~ntc stirking together or lwi.~.;,.g". It has been attempted to .~.r~e this problem by the ~rl~lition of additives and mo-lifi~rs in the coating.
20 When the impl~ntc are to be used for ~ dLion to hnm~nc or ~nim~lc, the additives which may be used are limited to those a~ al~ 'eS cleared for regulatory use. Polyester Cc~tin~c~ for toY~mrl~ have been cleared for re~ tory u e howeverthece ~lesen~ a particular problem in the pan coating method due to a&esion of the partide_ during the drying process. In ~rlrlitinn pinholes and other discontinnititos 25 can for_ in the outer coat during the drying process.
It would be desirable to avoid mutual contact of the impl~ntc during the drying process and to be able to control the drying process to avoid the formation of pinhnles and ~ co~ ;es There are freguent ci~ "~ n~es where impl~ntc are re~uired to provide a pulsatile release of an active ingredient. An example of such circurnstances is the so-called ~ W O 94/031~9 214 I 4 5 9 PC~r/A U93/00392 "one shot vaccine" concept. V~c~in~tion has been used to protect hllm~n~ and ~nim~lc against bacterial and viral infectious ~ice~c~os. In the case of vaccines prepared in the form of killed su~;~ions of bacteria or viruses, or in the form of conjugated tnYni~ls, repeated injections at specific ti_e intervals are required in order 5 for the v~crin~tion to effect adequate levels of i"""""ological res~llse. These intervals may typically range from a few weeks to several mont_s. Due to prevailing epiclçmiological, social, ec~"o",ic ~ce-~ibility, human tc~lA.\~t nt~l~ or simply collve,.ience reasons, it is highly desirable that effective protection against ~i~e~ces can be obtained with single injectionc In order to make this possible the one shot 10 v~ n~s have to release the actives at the fc~ el intervals, i.e. in a pulsatile mode, in the le~ ed profile, i.e. a "du~ ". A further applic ~tinn of the "one shot vaccine"
approach is a 6 month or 12 month contraceptive impl~nt or vaginal su~o~ito~
which delivers the contracc~ hormones in a sllcce~;Q.. of pulses, the active ingredient in this applic~tinn not being a vaccine.
A further no.l ~accillc ~Y~mple relates to the need for delivery of reaction mi~ctures to sites of action, specific~lly the delivery of the la~;~u~rn~ ce thiocyanate enzyme substrate re~tion system to the hin~ t~ of piglets in the control of diarrhoea.
La~;~o~.r~ e, coupled with a peroxide ge~ ~a~i~g ny~ e (eg, x~nthine and 20 x;-..lhi~.r nYirl~ce) CO~ SCN to SCNO, a very l~a;live and lethal ion for micro-Olg,...;~ . Pulse release terhnnlogy can be used to address the problem of rCi~r~
Constructing a delivery vehicle to meet these sorts of functional requirements 25 tlem~nfls a te~ hnology of m ~king co. . .p~ - 1 -. .ent~liced structures. The manufacturing process should ~,efelably be simpl~, v~ns~tile and ~m~n~hle to me( h~ni~tion and ~ llt-)m ~tic~n.
Although the most i ~ ~t attribute of a controlled release drug delivery device 30 is its capabilityto m~int~in a the.~ ;c~llyerr~ level of drug in an animal body over a srhedllled period of time, its adoption nltim~tely depends on the cost, co,lv~ n~e, and ease of its fabrication and ~.l...i..i~ation (1).
W O 94/03159 ~141 4 5 9 PC~r/A U93/00392 In terms of the ease and co..v.~..ien.-e of ~.~minictering these devices as imrl~ntc, shapes like sheets, films or hPmicpheres are generally impractical. However rods, nee~lles or cylinders are readily adapted for parenteral imrl~nt~tinn using a co~vGnlional hypodermic nPelle.
Pro.~llring eccentric shapes such as rods, n.-e.~lP~ ~r cylinders with the abovedescribed prior art methods, is also problematic. The pan coating and Wurster ro~tin~ methn ls are most ~mPn~hle to imrl~ntc of a generally rounded shape.
10 The applicant's cc,~l~-li.\g Appli.~tion PCI/AU93/00083 discloses a method ofmAkin~ imrl~ntc which are suitable for co..lillllous release of an active ingredient over a period of time which consist of a body member co".p,~ing a membrane forming a wall around a core matrix and co~l~ing material which is substantiallyiLIl~ViOUS to the active ingredient .-J~nt~inPc1 within the core matri~ The cylinder 15 is generally open ended, the active ingredient being rele~cecl directly through the open ends of the cylinder. In order to make an impl~nt suitable for pulsatile release using this terhni.lue, it is n~cpcc~ry to separately coat the open ends of the impl~nt This s~ate co~ting step is ~ clumsy, and time co.,~lmin~
20 A need accoldi~ exists for a simple and econnmi. ~l m~nllf~.-tllring process for imrl~ntc which can release bioactive materials and which can be readily adapted for comrl~Y in particular, pulsatile release of these materials.
AccoL.liLIgly, one aspect of the ~ se.~t invention cont~mrl~tPc a pulse release 25 imrl~nt com~ illg:
an axial biodegradable core;
a first concentric layer co~ g dehydrated hydrogel cont~ining an active ingredient; and an outer co~ting, said outer coating being removable by the environment in 30 which the imrl~nt will reside after ~I",i~ , ation.
--WO 94J03159 41 4 ~ 9 pcr/Aus3/oo392 In a further embodiment of the present invention there is provided a process of e~ lg a pulse-release impl~nt inrlnc~ing the steps of:
co~ting an axially tiicposecl biodegradable core material with a hydrogel cont~ining an active ingredient to form a conrentric coating;
S se~a,a~ing the coating into discrete se menn disposed along the core material;
dehy~ ~ing the h~l~ogel;
coating the discrete segm~ntc with an outer coating, said outer coating being removable by the ellvilo~ nt in which the imrl~nt will reside after ~rllni~ tion;
and removing the P~se~ core material to obtain the pulse release imp1~ntc The biodegradable core may be formed from any suitable material. Pl ~ fel ably the core is bioc~ tible. The core may be formecl from a string, suture or rod.
The term l~ vgel is uced in its ord~ art rec~p.-i~ed me~ninE of a watel-based three ~lim~ncion~l nonflowable amvl~hvus structure. The gel maybe created by ionic or hydrogen bond inter~innc. Hydrogels of particular mte.~ sl consist of a solution of a pvlymer in water which under controllable CO~ C can be made to adopt 20 either a fluid or semi-solid ~nfi~lration. This allows the hydrogel to be applied as a fluid to the core member and retain its shape as a semi-solid form. Methods toinduce the t~ ;ol- in~ e tell~ ul~ control or the use of cross-linking agents such as t~ lm ions. The te~la~u~ control ,llelllncl is suitable for gels such asagar and gelatine and the cross-linking metho~l is sllit~ble for hydrogels formed from 25 substances such as ~l in~te polymers.
In the ~rese~lt invention, a hydrogel in a fluid form is applied to the axial biodegradable core, a tr~ncition to a semi-solid state is in~ ec~ and the hydrogel is thereby immobilised. In this state, the hy-drogel may be cut and otherwise 30 maniplll~tecl When water is removed from the semi-solid form, a dehydrated hydrogel is form~.-l The dehy~ated hy~ogel forms a rigid solid which is suitablefor storage and h~n~11ing WO 94/03159 21. 41 ~5 9 PCI/AU93/00392 ~
Any suitable hydrogel may be used. F~mrles are gel~tine, agar, ~lginates~
carrageenan, gum gr~g~ nth, acacia, or corn starch. It may also be desirable to in~ le other components in the first concentric layer. F-~mrles are disintegrating agents such as corn starch, potato starch, alginic acid and the like and/or a lubricant S such as m~gnesillm stearate. Osmotic morlifi-ors such as sucrose and gl~1r~se may also be desirable. All such CO~ CIlLS, sho~iltl be subst~nti~lly pharmaceutically pure and non tc)x,c in the amounts employed and should be biocompatible and compatible with the active ingredient when used for human or animal use.
10 The active ingredient is typically a bioactive mc~lecllle and incl-1-les any native, synthetic or recombinant pharm~elltic~l agent or food additive or supplement in~ 1llclin~ antigens, antibodies, cytokines, growth promotants, hormones, cancer cell inhibitory moleclllP5 or agents, immllne stimlll~ntc or ~u~læc~ntc, anti-microbial agents inchl~tin~ antibiotics, anti-viral agents, vit~minc, minerals or inorganic or 15 organic nutrient~s. The active ingredient may ~~ ~c one type of bioactive molecule or may be a ~ ule of ~rr~e~ bioactive molecules. In a ~lefel~ed embodiment the active ingredient inclll~tes antigen~s from the clostridial family.
The outer ro~tin~ may be formed of any suitable bior~mratible substance. The 20 outer co~ting is generally meml~r~ous or polymeric and is sllhst~ntizllly illl~Cl vious to the active ingredient. The majority of the active material will be delivered or r~le~ced as a result of the removal of the outer co~ting ~...r~;..g the hrst concentric layer. F.~mple~s of suitable coating materials in~ e mo-iified starches, sugars, poly anhydrides, polyorthoecters, bioerodible polyc:,lcl:, and the polylacticlpolyglycolic 25 acid f~mily of polymers. Polylactic/polyglycolic acids are particularly suitable as they are widely commercially available v.~ith various degradation profiles and have regulatory clearance.
The co~ting may have a thickness of from typically lO~n to l,OOO,um depending on30 the app1ic~tion of the impl~nt and the permeability or degradability of the coating.
o 94/03159 ~! ~ 414 5 9 Pcr/Au93/oo392 Sli~ling The imrl~nt device may be in any suitable shape int lll~ine elongate, oval, round, ball, capsule, rod, needle, or cylinder shape. Conveniently, the shape is an elongate S cylindrical, rod or needle shape. In a most ~refe,lcd embodiment, the imrl~nt device is elongate and generally ~cal.
In the ~lucess of the present hl~ .~ion, an axially ~lisposed biodegradable corematerial is coated with a hydrogel Cb..~i"i,.g an actIve ingredient to form a 10 concentric co~ting~ .~m~ r clis~te gel se~n~ontc~ which remain supported by the biodegradable core can be created by cutting the outer concentric hydrogel layer in such a way that the biodegradable core remains intact and sliding the cut segment along the axially dis~osed biodegradable core so as to form a space between the discrete gel se~n~ntc This operationwill hereinafter be refe.l~ d to as the "cut/slide 15 operation".
The cut/slide operation may be ~,.;. r~" ...cd after the hydrogel has been dried and prior to co~tine hc.... ._r it is generally easier to ~.rulm the cut/slide operation on wet hydrogel. Ther~ rwe in the ~ocess of the l,ieseilt invention the separation and 20 dchy~llation steps may take place in either order. For ey~mrle the hydrogel may be dehydrated before se~ tion into discn te se~ ntc although it is preferred that the hydrogel is s_~atcd before dch~l~aliolL
The outer co~*n~ may be ~rplied in any suitable m~nn-or. For ~Y~mple, the outer 25 coa*ng may be applied by means of a mould, dipping, s~. aji,lg or by application via a "rod" or ' wic~".
The above cut/slide opera*on ù~reoll,es certain deffciencies of known prior art co~tin~ methods in that the problems of the impl~ntc st~ ng together during the 30 drying ploeess iS U~r~llle and the problem of pinholes and disco.~ ies in the- outer coat is alleviated as the drying process of the prese~t inven*on may be better controlled.
wo 94/03159 PCr/A~193/00392 ~
2~4145~ ' Once the outer coating has been applied, the exposed core material may be cut away rçsllltin~ in discrete pulse release impi~ntc.
The process of the present invention is readily adaptable for incorporation of heat S labile active ingreriisntc. It pl~esen~ few COllaLldiL~tS wlth respect to the choice of active ingredients; and it should be noted that by usl~g a biodegradable structural :~iU~ ul l, such as surgical suture, the central core does not need to be removed from the final imrl~nt product.
10 The present device also provides the basis on which further r~fin~m~nt or sophistil ~tinn of release can be effected. For in~n~ e by usirlg as the hydrogel layer bioerodible polyorthoester polymerc prepared by the reaction bet~veen 3,9-bis(ethylidene-2,4,8,10-tetrau~iro [s~s]-lln~lec~ne) and various ratios of trans-cyclohto~neclimethanol and 1~6-hey~n~linl (2), the production method can be readily 15 adopted for mass production of needle injectable imrl~ntc of ~,.til",nour agents such as 5 flu~o-~l acil for release in a time independent mode. Likewise, by using collagen poly (HEMA) ~ gel (1) as the .~ ~g ma~, needle injectable impl~ntc can be readily mass pro lllre~l for a variety of hydlu~hilic or hydrophobic active snhs~n~e with again a time in~lepPn~lent release mode.
The reciriçnt of the imrl~nt may be a hnm~n, livestûck animal inr l~ ing a rnmin~nt ~nim~l, e.g. a sheep, cow, horse, pig, goat or donkey, poultry, e.g. chicken, turkey, goose or game bird, a la~,olatc,ly test ~nim~l, e.g a rabbit, guinea pig or mouse, Co",~-Z "ion ~nim~l e.g. dog or ca~, or a wild animal in the captive or free state.
minictration of the imrl~nt may be by any co~vc;-lient means but is generally byinjection via the h~LldVenOIlS, i~L~d~-;lo~ l, intr~m-lcc-ll~r, sub-c~lt~n~ous or intradermal route. The device may also be surgically imrl~ntefl or imrl~ntecl by sub-surgical procedures such as during biopsy procedures. Devices such as these may aLo 30 be ~.l",i"i~ered by an oral route.
.
The amount of active ingredient used in a given imrl~nt will vary depending on the ~Wo 94/031S9 21~14 5 9 PCI/AU93/00392 '~ f;
_ 9 _ type of bioactive molecule, con~lition in the animal being treated and the presence or ~hsçnre of agonists to the active ingredient or ~nt~gonicts to the con-lition being treated. In general, an effective amount of active ingredient is employed meaning an amount effective to in~ln~t, stim~ te, promote or otherwise initi~te the imrnediately S intPn-ied result~
, ~
For tY~mp1e, if the active ingredient is an antigen, the effective amount is that required to stim~ te an imm1mr rt.~l-~c to tihe ~ntig~on Commonly, the active ingredient will be present in amounts ranging from a few micrograms to gram 10 quantities per imrl~nt The invention will be further described by r~relellce to the following non-limiting figures and ~ s I~ the figures:
Figure 1 is a part section~1, part srhtm~tir, cross section of an apparatus 15 suitable for ~ g imp1~nt cores by rhrmis~lly in-l11recl gelling.
Figure 2 is a part section~1, part srhtm~tir cross secti~ n of an apparatus s1~it~hle for ~ari~g imp1~nt cores by te~ldlule in-lurecl gelling.
Figure 3 is a srhrm~tic illu~Ll~Liol. of spray co~ti~ of hydrogel impl~ntc.
Figure 4 is a schematic illustration of rod co~ting solvent based polymer 20 co~ting app1ir~tion Figures 5 and 6 are graphs of dye release from 35% (pLa i.v. 1) to1l11ene rod coated gelatine core imr1~ntc; in vitro at PBS at pH 7.2, 37 C.
Tn~l~nt Y~ ;
Apparatus suitable for use in the method of the ~csellt invention varies depenrling whether the gel results from tG~lature or rh~-mic~1 effects. Figures 1 and 2 are30 part section~l~ part srhrm~tir cross sectionc of the a~ Lu~ for preparing imp1~nt cores. In one embo-limrnt i~lustrated in Figure 1 for rhrmir~11y in-i11refl gelling, the a~dld~us concictc of a dialy is tube "1" fitted over an upper end portion "2" and a WO 94/03159 ~ i PCr/AU93/00392 ~
2 1 ~ 9 lower end portion "3" and located in sealing engagement by wate:,~rwf rubber sealants "4" and "5". A ~u~ ing line forrneci of bioerodible core material "6" is m~int~ine~i under ten~ion by a spring steel bow "7". An inlet port "8" and bleeder hole "9" are provided respectively in the lower and upper end portions "2" and "3".
S An outer perforated mould "10" is provided to ~u~ l the dialysis tube "1" and allow the ingress of geliing reagents to the dialysis tub~. ~is outer perforated mould may be hinged to allow easy access to the dialysis tube.
In an alternative embodiment illustrated in Figure 2, s~lit~hl~ for te~ u~e 10 in~ ceci gelling, the dialysis tube "1" is repl~ced with a teflon tube "11" which may be in two longitllriin~l halves and the outer perforated mould "10" is replaced with a j~t~keteci te.n~e~-ature control member "12".
For structural stability of the gel during subsequent processing the gel structure is 15 held on the ~u~w ~ "6". For symmetry and ~ ~ the ~u~ "6" is centred using the upper and lower end portions "2" and "3". The ~u~ line "6" is kept taut using a device "7" made of spring steel r~os~mbling a bow. This device serves also as a handle to Lla~ the gel structure for the coll~..;Pnc~e and security of subsequent gel l~luce~ g, e.g. drying and co?tin~
Referring to Figures 1 and 2, a central su~ which forms the bioerodible core "6", e.g. a surgical suture, is p~citiontod at the radial centre in a cylindrical mould "1" or "11" using a~ ,yliate pocitirming guides. For water based polymeric matrices, the inner s~ e of the mould should be lined with material such as teflon to f~ilit~te 25 cast removal.
A temperature se~ ive impl~nt hydrogel layer or core matrix on the central ~ L
may be prepared in the following m~nner:
Insert the hol;"~ lly sectioneci teflon tube "11" into the j~rk.o.tecl temperature control member "12" with a~.. ,c;.n~t~ly 1.0 cm of the teflon tube protruding from one end of the glass tube.
2 Run the ~u~l l line "6" through the bottom end portion "3" and knot ~ W 0 94/031~9 ~ 1 4 1 ~ 5 9 PC~r/A U93/00392 on the external side of the end portion "3" to ensure the line does not pull through (see Step 9 below).
3 Pass the support line "6" through the mould (teflon tube "11" in the glass holder "12").
4 Insert the protruding section of the teflon tube "11" (from step 1) into the bottom end portion "3" (the analogy used was "like a condom").
S Push the teflonlseptum plug "11"/"3" into the glass tube "12" as far as possible (on the whole this remains 'outside' the glass tubing).
6 Seal the teflon/septum plug "11"/"3" by çn~cing the glass tube and septum end in the watel~oof rubber sealant "4", e.g. wrap in parafilmTM.
At this point either of two procedures may be followed. That is, either the mould is filled and the top end cap "2" put into position and the whole device sealed. Alternatively, the top end cap "2" is put into position and then the mould is filled and sealed.
7 Fill the mould with the required gelling sollltinn using a syringe.
8 Run the top end pUl Lion "2" onto the ~u~Ol ~ line and insert the top end portion "2" into the top of the teflon/glass tubing "11"/"12".
9 Hang the entire moulding unit from the ~u~ line to align the ~u~ line "6" along the centre of the mould.
10 When cured ~licm~ntle the mould and pull out the SU1JPU1L line "6" with the core matri~c ~tt~ e~
(2) Tmpl~nt Hy~rogel ('nre Pre~ tion The matrix active ingredient and the hydrogel material in the gelling mix is colll~ounded accor~ g to the individual formlll~tions used. Usually the sollltionc of hydrogel and active materials are ~ic~ed separately and recoml,illed in the ~ ~l Lion prescribed imm~ tely prior to filling into the mould to minimice any possible clen~nlration or inactivation of the active W O 94/03159 ~ PC~r/AU93/00392 ~
2 ~
during the preparation of the hydrogel solution.
(i) T.o."~r~tllre in-lnrr~l gellin~g pro(rcc S The assembled mould, the gelling mix and the filling device (eg a syringe) are separately equilibrated to the desired fi~Lng temp L d~l~e. Thermal prefilling equilibration is desirable to prevent bI~kage during filling and deformities in the gel structure.
2a The plc~alation of the tem~.a~ in~hlreci gelling solution involves diccolntion of a hydrogel, such as gelatine (270 mg), and, if required, an osmotic modifier such as sucrose (750 mg) in water (1.5 ml). The stock hydrogel solution is ~ aled by he~ting the suspended solutes in a water bath at 100C. Subsequent to rlicsollltion, fluidity of the hydrogel sollltion is best m ~int~in~ll by hokling at 37 - 45 C.
2b A stock 'bioactive' sollltion is ~ cd by flic~ol~ltinn of the 'active' in water (0.5 ml). This s~ ltinn is then held on ice.
2c ~ nrc~cc~ry, the requisite volume of the stock 'bioactive' solution is diluted to the lc~ e cQ..- e ~ iull by ~icsollltion with water. This snllltion is also held on ice.
2d 0.5 ml of the stock 'bioactive' solution or diluted 'bioactive' solution isheated to 37C then combined with the stock hydrogel solution (1.5 ml) to give the gel sohltinn The combined hydrogel and active agent solutions are then mixed for 1 minute at 37 C and dispensed into the moulds.
2e The gelling mi~ may be introduced to the mould by a syringe pump via the inlet "8" while the bleeding hole "9" provides an outflow for air and excess gel solution. Filling is ~refeldbly ~ccomrli~hed by one slow collt;.l..ous action. Byfi~lingfrom bottom ~w~Ld the process is made e~çnti~lly trouble free and there is lesser likrlihood of deformities in the gel structure due to ocrlllded air bubbles especially in a clean teflon mould. Filling is ~mplrted when gelling mi~c appears to flow ~O 94/03159 21 ~1 4 5 9 Pcr/Au93/oo392 . .
from the outlet bleeding hole in the top positioning guide.
2f Foliowing filling the comr1ete ~cs~omhly is m~int~ined at the filling t~ ature for a short time and a check for proper filling is made.
2g Gelling of the matrix/active solution mix is ~ccQmr1iched by lowering S the ambient tem~l~ture in the thermal jacket slowly. A slow transition is desirable to ~ ellt defc.lmiLies in the gel structure. To ensure good results, the u~mr1ete ~cs~ombly is kept at a temperature well below the critical gelling temperature for a period of time, for ~mrl~ 30 ~ t~ s.
(ii) (~h~mir~lly or ion in-ln~.o~l ~11in~
For polymeric matrix materiaLc which forrn a solid gel when in contact with a di- or trivalent cation or a catalytic agent, the supporting string, is centred by the ~iLiOllillg guides "2" and "3". The Su~l l line "6" is kept taut using a device "7" within an a~ro~liate dialysis tubing "1"
which in turn is çn~ se~i within a rigid ~Çolatel ~ ~ll "10" for the e--;enl e of filling and ~ l)se~luent in~ nn of gelling.
20 (3) Filling 3a Ion or ~h~.~ni~lly in~ e~i gelling is best achieved ucing the perforated mould ass~ ly "10" with filled dialysis tube "1". This assembly is filled ~ler~lably by one slow co,~l;"llous action. By filling from bottom u~w~d the ~rocess is made .o.ccenti~lly trouble free and there is lesser lik~.lihoo-l of derulllli~ies in the gel structure due to ocç111rled air bubbles a&ering to the dialycis tubing.
3b Filling is c~mp1eted when gelling mi~ appearc to flow from the outlet bleeding hole in the top positioning guide.
3c Following filling the complete ~c.c-o.mhly is m~int~ine~i at the filling tem~ ature for a short time and a check for proper filling is made.
3d The assembly is then ~r~ed to a c~t~er of the in~l11cer solution WO94/03159 ~,~4~4S9 PCr/AU93/00392 ~
~vhich may be held at any ~,erelled temperature, for example, at zero degrees Celsius if den~lration of an active is a concern. Equilibration of the in~lllrPr across the semi-permeable membrane affords the gelling of the matrix active solution mix.
3e Extra time should be allowe~ to ensure proper gel formation and possible hardening of the ~ structure for ~Y~mplP, 240 mimlt~os"
(4) Remov~l of gel sh~l-hlre from monld Depending on the gel structure strength, fresh gel structures on the ~u~po are usually very fragile and thus not readily lifted ho~ .t~lly off the mould.
Hence they are ~,~f~lably kept in a vertical position and the t~vo halves of the mould gently se~alated. To ~ n~ m~ging the gel structure, the top po~itioning guide should be removed before the removal of the mould halves but the bottom guide should remain in place.
(S) ~ gment~tion of the ~el ~h~l~hlre The moulded gel structure lerc.l~d to above c4..~ c of an outer hydrogel layer which is ~up~l~ed by and ~-~ .I.ic about an axial ~u~oll line.
.~m~ller discrete gel se~ P~t~ which remain ~u~lLed by the axial ~u~
line can be created by cutting the outer ccs--~..l~ic hydrogel layer in such a way that the axial line remains intact and sliding the cut segrnent along the axial line so as to form a space bet~veen the disc,~ete small gel segments. The above cut/slide operation may be ~lrollL~ed either before or after the concentric hydrogel layer has been dried and prior to Co~ting Huw~ver, it is generally easier to perform the cut/slide operation on wet hydrogel.
(i) The "long section" may be segm.onted into lengths, e.g. 10 mm, m~int~inP~ on the support line "6". The ~U~Ul led segments may then be dried and processed as required for specific applic~tions.
~WO 94/03159 21414 5 9 i pcr/Aus3/oo392 (ii) In an alternate emborliment, the core matri~ may be sectioned subsequent to drying but prior tO coating.
(6) Drying Depending on the molec~ r stability of the active cu~ oulld and speed of drying, the water based gel structure may be air dried under ambient con~itir)nc or at low te~ atures (e.g. at 2 C) by flllching with dry nitrogen gas. For ~ mrle, a gel structure CQ~ g about 10~o total dry matter takes 8-10 hours to dry the gel to a co~la,lt weight at room temperature (21 C).
The drying time will be appreciably longer at lower te~l alul es. The drying times are gel co~ o~ ion Clepen~ nt (7) (~o~tin~ of ~he (~Jt~ tllre (i) Once dried the gel structure mounted on the support may be re~cct~mhled with the 2 halves of the teflon mould of the same internal or dirrelc.,t internal (li~nnett~r to allow for the bioerodible outer co~ting to be ~rrliecl to the core. Thus, after the ca~ct is formed and dried, the dry cast may be coated with a water ;.,.~.~ .".eable co-polymer such as polylactic acid (pLa)/polyglycolic acid (p&a) (85:15) co-polymer to form a co~ting (ii) Alternatively the dried gel structure on the su~l l "6" may be coated by repeated dipping into a polymeric sohltion and drying to achieve a thin layer of a s~ "l i~lly water i~ ~eable coating with specific tl~S~ characteristics (refer to Fy~mple 3).
(iii) Alternatively the dried gel structure on the ~u~ "6" may be coated by repe~tecl ~Lyillg with a polymeric solution and drying to achieve a thin layer of a s~ st~nti~llywater impf-rme~ble coatingwith specific characteristics (refer to F~mrle 4).
Wo94/03159 ~,~4~4S9 PCr/AU93/00392 ~
(iv) Alternatively the dried gel structure on the support "6" may be coatedby repeated applir~tion of a polymeric solution via a "rod" or '~vick"
and drying to achieve a thin layer of a snhst~nti~llywater impermeable coating with specific 11 ~a~ characteristics (refer to F~mple S).
(8) ~ ce Profile Control For manip ll~ting the release characteristics, the release mode of the present device can also be modified by the cQn~e~ alion and com~osition of the matrix materials. For ~y~mrle~ when agar was used as the matrix material, the release was faster and the extent of release higher. This demonstrates the ability to affect the release rate by changes in matri~c composition. Variationsin~ lcle repl~çment of the water based hydrogel matrix with hydrophobic materials such as glycerol monoste~rate.
lS
l;XAlVl P~ .F. 1 - Fabrication of imrl~nt cu~ human serum albumin (HSA) andhnm~n IgG
This ~Y~mrle is illL~LraLi~.. of te~lature in~hl~ecl gelling and gives evidence of an 20 i ~ ogical les~ollse to an incc,l~l ated ~ntigen Flc;y~,~t;nn of Tmpl~nt 0.9 ml of HSA/hllm~n IgG soll~tion (9.5 and 5.8 mg/ml respectively in 0.1 M NaCl) 2S were miYed with O.S ml of 1~o NaCl solution and the mixture equilibrated to 43 C.
It was then mixed with 4.6 ml of gelatine/agar matri~c solution (13% and 1.3% w/v respectivel~, gel~tine, cell culture reagent from Porcine stein, approx 300 bloom, Si~na catalogue no. G1890) also equilibrated at 43C. The reclllt~nt mixture wasd to the mould assembly eguilibrated at 43C with a 7 mm internal 30 diameter x 20 mm long teflon mould and a 0.4S mm cli~meter ~" line as the centre ~uy~o- l. The inlets to the moulds were then stoppered and the moulds were allowed to e~uilibrate at 43C for 10-1S minlltes before the temperature of the ~O 94/03159 2 ~ 4 1 ~ 5 9 PCI /AU93/00392 , thermal jacket was slowly lowered to that of mnning cold tap water at about 20 C
over 20 mimlteS. The gel was then soliclified by cooling the mould assembly to 0 oc and m~il.t~ i..g it at that temperature for half an hour. After the mixture soli~lifiecl the moulds were r1icm~ntled and the gel structure on a string stretched in a bow was S removed carefully in a vertical orient~tion to avoid hc,l~ullLal splitting of the gel structure by the stretched ~u~ while the gel structure was still fragile. The gel structure ~UypOI led by the string ~up~ll in a bow were cut and separated in thecut/slide operation and air dried at room temperature overnight (about 18 hours).
The dried gel structures were then coated with a water based polyacrylic resin 10 Eudragit E 30D by five repeated cycles of dipping in an Eudragit suspension for 30 seconds and drying for 60 minlltes~ Eudragit E 30D is an aqueous dispersion of poly(meth)acrylic acid esters supplied by Rohm Pharma GmbH Weiterstadt Darmct~lt West Germany. When dry, the gel structures were dismounted from the bow and trimmed to se~m~-ntc of 1 cm length (diameter 3 mm). Each segrnent was 15 estim~terl to co.-l~;.. 0.051 of the original HSA/h-lm~n IgG antigen solution.
Placebo imrl~ntc were made in exactiy the same way as the antigen impl~ntc except that the HSA/hl~-n~n IgG sol-~tinn was replaced by 0.9 ml of 0.1 M NaCl.
20 Fv~ tinn nf Tmrl~nt Sheep previously ;~ cd with human serum were imrl~ntecl subcutaneously on the inside sulr~ce of hin-lle~c using a me~h~ni~l imrl~nt~r fitted with a 2.8 mln internal ~ met~r n~eclle- Two im~l~nt segm~ntc co..~ -g antigen or placebo were 25 given to each sheep.
To determine the antibody les~,.ce) blood s~mpl~s were taken from the sheep prior to receiving imrl~ntc and on days 9, 15 and 23 following impl~nt~tion. Sera wereobtained from blood s~mrles by standard sernlogit~l practice and assayed for 30 ql-~lit~tive and qll~ntit~tive antibody titres using double immllno diffusion and ELISA (Enzyme T.ink~l Tmmllno Sorbent Assay) te~hni~lues respectively.
2 ~ 4 '~ ~ PCr/AU93/00392 Rt~cnl~c Results of double immnno diffusion assay showed that there was an increase of antibody titre in recipients of the HSA/human IgG imrl~ntc but not in those of the 5 placebo. The increase in antibody titre was r~ .able to that obtained when norrnal immnnic~tion protocol with adjuvanted antigen ~us~nsion was used. As shown in Table 1, the le;,~ollse in general wac m~rim~l at day 9 of the four scheduled s~mrling days for both the specific anti-IgG and anti-HSA responses.
~ im~l increases at day 9 ranged from four to thirteen fold for anti-IgG re.,~l~sc 10 and seven to twent~five fold for anti-HSA. Titres were notably high relative to those in sheep receiving adjuvanted antigen suspensions, with amounts of specific antibodies approaching the highest that has yet been obtained from a few select sheep (that is in the order of 32 units of antibody in the sheep serum to either the HSA or human IgG). For three weeks following imrl~nt~tion, antibody titres 15 rem~inecl signifil ~ntlyhigh but decreased with time in the antigen imrl~nte~ ~nim~lc In addition to the at least equivalent 1 ~s~ es obta~cd, i l l l l l l ll i~ i.c~tion using antigen imrl~ntc can afford a ~lu~ber of other alY~tages. T...~ i.c~fion with imrl~nt.c was very simple to ~....1~,1l~ and cr....~.~lcd with the louLiL.c method far less time 20 co.. ~.. ing Apart from the puncture mark caused by the imrl~nt~r needle, no ulceration or swellingwas evident at the imrl~nt site. This is in sharp contract to the sitll~tion of rouli~e practices when ~nti~n ~u~ innc, especially those using Freund's adjuv~, are used for ;.~ ...ic~ti.m ~0 94/03l59 2 ~ 59 Pcr/Au93/oo392 TABLE 1 - Qll~ntit~tive Antibody Response by ELISA Method of Deterrr~ination Sheep Tmrl~nt Day O Day 9 Day 15 Day 23 No.
S Anti-IgG Re~ .se 7 Antigen 3.3 19.9 (6.0X) 15.2 (4.6X) 9.6 (2.9 X) 9 Antigen 1.7 1?.8 (10.SX) 14.0 (8.2X) 9.9 (5.8X) 3 Antigen 0.9 11.7 (13.0X) 8.9 (9.9X) 6.4 (7.1X) O Antigen 7.0 24.9 (3.6X) 28.3 (4.0X) 25.3 (3.6X) 8 Antigen 1.2 8,5 (7.1X) 6.9 (5.8X) 5.0 (4.2X) Placebo 2.0 2.0 (1.OX) 2.2 (1.lX) 2.1 (1.lX) 6 Placebo 4.8 8.8 (1.8X) 8.2 (1.7X) 6.1 (1.3X) 4 Placebo 3.9 4.1 (1.lX) nd- nd-Anti-HSA R~ se 7 Antigen 1.6 15.7 (9.8X) 13.2 (8.3X) 8.0 (5.0X) 9 Antigen 1.0 21.1X (21.1X) 19.4 (19.4X) 14.5 (14.5X) 3 Antigen 0.9 22.3 (24.8X) 20.6 (22.9X) 14.2 (15.8X) O Antigen 3.5 23.8 (6.8X) 26.6 (7.6X) 18.9 (5.4X) 8 Antigen 1.5 13.3 (8.9X) 12.2 (8.1X) 9.8 (6.5X) Placebo 1.0 0.9 (0.9X) 0.9 (0.9X) 0.9 (0.9X) 6 Placebo 4.9 6.4 (1-3X) 6.0 (1.2X) 5.8 (1-2X) 4 Placebo 1.7 1.5 (0.9X) nd- nd-nd = not det~ ~ Illilled; figures in brackets l~lesent the mllltirle increases over day O
WO 94/0315~ ~ 4~ 4S 9 PCr/AU93/00392 .F. 2 This ~ m~le is illustrative of chemical in~lllre~ gelling and is preferred for heat labile active material.
The ion in~ cerl gelling mould was assem~ed as described above (refer to Figure 1) and equilibrated at room tempelaLure. 7 ml of 3% w/w aqueous sodium ~lgin~te [Sigma Co. cat No. A-2033, alginic acid sodium salt medium viscosity, from M~rrocystic ~yl ;r~ (Kelp)] was mixed thoroughly with 7 ml of (~loctrit1illm nnvyi 10 toxoid at room te~ ature. The active ~uspel~sion was a concentrated solution of ~lnctrirlillm ~ toxoid cc~ llg the toxoid produced by the bacteria and 5.3 mg/ml of hydrated ~lllminillm hy~l~ide added as adjuvant. Although there is a slight increase in viscosi~y, the two ~ ion~ may be held at lower temp~ es (eg 4C) and mixed at lower telll~ldlL~es. The reslllt~nt mixture was transferred 15 with a syringe via the inlet port in the mould ~cc~mhly to fill the dialysis tube inside to a slight overflow from the ouclet bleeder hole with about 7 ml per mould. The two mould ~c.c~mhlies were ~i~.~ed into a bath of 500 ml aqueous AlCl3 sollltinn (0.5% w/w) at room tempe~a~ul. (or if desired at 1C) with continllQus slow ~git~tion using a m~gn~tic stirrer. Gelling was usually effected within 2-3 hours of 20 imm~orsinn but it is our nnrm~l practice to leave the gel structures to form for 4 hours. Following gel structure form~tion the moulds were removed from the gels in a vertical position The reslllt~nt gel structures were allowed to dry at room te~ dlule. When dry, the gels may be surface coated with Eudragit E 30D as previously described and/or reloaded with another layer of toxin ~Igin~te gel 2~ structure.
If desired sodium ~l~in~te may be directly ~lb~l;t~n~d by K-carrageenan but the tempelalule during filling of the tube mould needs to be higher to l~leV~llt premature gelling of the K-carrageenan.
Also if rapid gelling of the matrix active sollltinn is required, the gel inr~ ing agent, AlCl3, (e.g. 7 ml of 1.5% snllltinn) can be added directly to the 14 ml of the ~Igin~te ~Wo 94/03159 ~ 4 f 9 5 9 pcr/Au93/oo392 ~. n~vyi mi~ and the rtos..lt~nt solution mixed thoroughly and quickly.
l~XAlUP~ F 3 S This loY~rnrle illustrates the terhnique of dip coating of hydrogel irnplants and provides evidence of pulsatile release in vitro ev~ tion Polylactic acid (d,l-pLa) of inherent vi ,oosi~y (i.V.) = 1.0 dl/g (supplied by Boehringer Ingelheim) of mass 12 g wac dissolved in 120 ml of dichlorometh~n.o 10 Phosrh~te l~u~Lred saline (PBS), pH 7.2 was made accoldillg to the following recipe:
NaCl (80.00 g), KCl (2.00 g), 2HPO4.12H2O (15.36 g), KH2PO4 (2.00 g) dissolved in 1000 ml of lictilleri water.
The l~ ogd cores cQnt~ining red food dye or antigen were m~nllf~rtllred according 15 to the methodology described above using the cut/slide method.
Refel~g to Figure 2, dried hydrogel cores on the ~u~ line "6" attached to the spring steel bow "7" were dipped into the sollltirm of polylactic acid in dichloromçth~ne. Tmmersion time was 30 secon-ls for each coat. Upon removal from20 the polymer s~ ltion the excess polymer sollltir)n was allowed to run down the imrl~ntc and the hanger was then inverted to allow the polymer to run the other way: this aids in spreading the polymer evenly over the impl~ntc As illustrated in Table 2, groups were dipped either four times, i.e. 4 coats or si~c times, i.e. 6 coats.
At least one hour drying time was allowed bet~veen coats to ensure adequate drying 25 under the ~mbient conr~ on~. Individual cut impl~ntc were each placed in individual glass vials. PBS of volu_e 10 ml was added to each vial and they were placed in an incubator at 37 C. Molli~o~g wac carried out using U.V. visible spectroscopy tOme~cllre dye release into the solution.
S pcr/Au93/oo392 itions Number ofNumber of Coats T~ erature (C) pH
Sarnples 7 4 37 7.2 7 6 37 7.2 10 One sample commenced dye release early at day 4 and took 14 days tO attain 100%
release at day 18.
Of the rem~ining replicates mean release was at day48. The same impl~ntc attained a 100% release profile in an average of 5.3 days +/- 2.7 days. All s~mples 15 commPn~ecl dye release within a si~c day period bet~veen days 45 and 51. The total release time from when the first of the six impl~nt~ comm~n~ed dye release ( ~10%
release) to when the final imrl~nt reached 100% release was 14 days, i.e. from day 45 to day 59.
20 There appeared to be no st~tictic~lly signifir~nt ~lirrGlGnce between s~mrl~c with 4 coats and those with 6 coats. This is ~ ected as the pLa polymers are, in general, buL~c eroding thus are generally unaffected by sarnple thickn~ss The results show a ~ignifi~ ~nt delay in the time of onset of release of die comr~red 25 to uncoated s~mrl~s which gave 100% release within 3 hours of imrnersion in PBS.
F XA~IPF F. 4 - This ~r~mrle illustrates spray coating of hydrogel impl~nts and provides evidence of 30 pulsatile release from an in vitro eY~min~tion ~WO 94/03159 21414 S 9 PCr/AU93/00392 Polylactic acid (d,l-pLa) of inherent viscosity (i.v.) = 1.0 dl/g (supplied by Boehringer Ingelheim) of mass 12 g was dissolved in 120 ml of dichloromethane.
Phosphate buffered saline (PBS), pH 7.2 was made according to the following recipe:
NaCl (80.00 g), KCl (2.00 g), 2HPO4.12H2O (15.36 g), KH2PO4 (2.00 g) dissolved in 1000 ~nl of distilled water.
The hydrogel cores cont~ining red food dye or antigen were manufactured according to the methodology described above using the cut/slide method.
An ~tomicing spray nozzle connt~cted to a ~""u,essed air cylinder and to a 250 ml separating funnel which cont~ine~l the diLrerent polymer solutions was used to apply the polymer to the gelatine cores being rotated about the ~iU~ line using a "rotisserie" mech~nicm (refer to Figure 3). A polymer sol-ltion was sprayed onto the imrl~nt cores using air brush with a g~c ~lcs~ of 200 kPa and a ~lict~nce of 10-30 mm bclwcen the air brush outlet to the imrl~nt cores. The imrl~nt core string was hand rotated during Spl~yil~g in order to obtain .."ir~... co~ting. 65 ml of polymer solution was sprayed on a string of imrl~nt cores.
20 Referring to Figure 2, the position on the ~up~l line "6" of all imrl~ntc was noted, seven of those were selected at 1~dO1LI and their weights recorded. Tmrl~ntc ~vere placed in glass vials. PBS of volume 10 ml was added to each vial and they were placed in an ill~ubatol at 37 C and pH = 7.2. The d,l-PLA (iv = 0.1 dl/g) produced an opague papery coating which had a granular appearance. Despite their 25 appearance swelling without releace was ~ale"t from an early stage.
Results of the incubation work are given in Table 3. Seven imrl~nt.c were placed in individual s~mrle vials ront~ining 10 ml rhnsph~te buffer pH = 7.2 and incubatedat 37 C. MO~iLO1 illg was carried out using U.V. visible spc~ L~ osco~y to measure dye 30 release into the snlllti-~n One imrl~nt started to release on day 36, others started to release between days 73 and 79.
S Push the teflonlseptum plug "11"/"3" into the glass tube "12" as far as possible (on the whole this remains 'outside' the glass tubing).
6 Seal the teflon/septum plug "11"/"3" by çn~cing the glass tube and septum end in the watel~oof rubber sealant "4", e.g. wrap in parafilmTM.
At this point either of two procedures may be followed. That is, either the mould is filled and the top end cap "2" put into position and the whole device sealed. Alternatively, the top end cap "2" is put into position and then the mould is filled and sealed.
7 Fill the mould with the required gelling sollltinn using a syringe.
8 Run the top end pUl Lion "2" onto the ~u~Ol ~ line and insert the top end portion "2" into the top of the teflon/glass tubing "11"/"12".
9 Hang the entire moulding unit from the ~u~ line to align the ~u~ line "6" along the centre of the mould.
10 When cured ~licm~ntle the mould and pull out the SU1JPU1L line "6" with the core matri~c ~tt~ e~
(2) Tmpl~nt Hy~rogel ('nre Pre~ tion The matrix active ingredient and the hydrogel material in the gelling mix is colll~ounded accor~ g to the individual formlll~tions used. Usually the sollltionc of hydrogel and active materials are ~ic~ed separately and recoml,illed in the ~ ~l Lion prescribed imm~ tely prior to filling into the mould to minimice any possible clen~nlration or inactivation of the active W O 94/03159 ~ PC~r/AU93/00392 ~
2 ~
during the preparation of the hydrogel solution.
(i) T.o."~r~tllre in-lnrr~l gellin~g pro(rcc S The assembled mould, the gelling mix and the filling device (eg a syringe) are separately equilibrated to the desired fi~Lng temp L d~l~e. Thermal prefilling equilibration is desirable to prevent bI~kage during filling and deformities in the gel structure.
2a The plc~alation of the tem~.a~ in~hlreci gelling solution involves diccolntion of a hydrogel, such as gelatine (270 mg), and, if required, an osmotic modifier such as sucrose (750 mg) in water (1.5 ml). The stock hydrogel solution is ~ aled by he~ting the suspended solutes in a water bath at 100C. Subsequent to rlicsollltion, fluidity of the hydrogel sollltion is best m ~int~in~ll by hokling at 37 - 45 C.
2b A stock 'bioactive' sollltion is ~ cd by flic~ol~ltinn of the 'active' in water (0.5 ml). This s~ ltinn is then held on ice.
2c ~ nrc~cc~ry, the requisite volume of the stock 'bioactive' solution is diluted to the lc~ e cQ..- e ~ iull by ~icsollltion with water. This snllltion is also held on ice.
2d 0.5 ml of the stock 'bioactive' solution or diluted 'bioactive' solution isheated to 37C then combined with the stock hydrogel solution (1.5 ml) to give the gel sohltinn The combined hydrogel and active agent solutions are then mixed for 1 minute at 37 C and dispensed into the moulds.
2e The gelling mi~ may be introduced to the mould by a syringe pump via the inlet "8" while the bleeding hole "9" provides an outflow for air and excess gel solution. Filling is ~refeldbly ~ccomrli~hed by one slow collt;.l..ous action. Byfi~lingfrom bottom ~w~Ld the process is made e~çnti~lly trouble free and there is lesser likrlihood of deformities in the gel structure due to ocrlllded air bubbles especially in a clean teflon mould. Filling is ~mplrted when gelling mi~c appears to flow ~O 94/03159 21 ~1 4 5 9 Pcr/Au93/oo392 . .
from the outlet bleeding hole in the top positioning guide.
2f Foliowing filling the comr1ete ~cs~omhly is m~int~ined at the filling t~ ature for a short time and a check for proper filling is made.
2g Gelling of the matrix/active solution mix is ~ccQmr1iched by lowering S the ambient tem~l~ture in the thermal jacket slowly. A slow transition is desirable to ~ ellt defc.lmiLies in the gel structure. To ensure good results, the u~mr1ete ~cs~ombly is kept at a temperature well below the critical gelling temperature for a period of time, for ~mrl~ 30 ~ t~ s.
(ii) (~h~mir~lly or ion in-ln~.o~l ~11in~
For polymeric matrix materiaLc which forrn a solid gel when in contact with a di- or trivalent cation or a catalytic agent, the supporting string, is centred by the ~iLiOllillg guides "2" and "3". The Su~l l line "6" is kept taut using a device "7" within an a~ro~liate dialysis tubing "1"
which in turn is çn~ se~i within a rigid ~Çolatel ~ ~ll "10" for the e--;enl e of filling and ~ l)se~luent in~ nn of gelling.
20 (3) Filling 3a Ion or ~h~.~ni~lly in~ e~i gelling is best achieved ucing the perforated mould ass~ ly "10" with filled dialysis tube "1". This assembly is filled ~ler~lably by one slow co,~l;"llous action. By filling from bottom u~w~d the ~rocess is made .o.ccenti~lly trouble free and there is lesser lik~.lihoo-l of derulllli~ies in the gel structure due to ocç111rled air bubbles a&ering to the dialycis tubing.
3b Filling is c~mp1eted when gelling mi~ appearc to flow from the outlet bleeding hole in the top positioning guide.
3c Following filling the complete ~c.c-o.mhly is m~int~ine~i at the filling tem~ ature for a short time and a check for proper filling is made.
3d The assembly is then ~r~ed to a c~t~er of the in~l11cer solution WO94/03159 ~,~4~4S9 PCr/AU93/00392 ~
~vhich may be held at any ~,erelled temperature, for example, at zero degrees Celsius if den~lration of an active is a concern. Equilibration of the in~lllrPr across the semi-permeable membrane affords the gelling of the matrix active solution mix.
3e Extra time should be allowe~ to ensure proper gel formation and possible hardening of the ~ structure for ~Y~mplP, 240 mimlt~os"
(4) Remov~l of gel sh~l-hlre from monld Depending on the gel structure strength, fresh gel structures on the ~u~po are usually very fragile and thus not readily lifted ho~ .t~lly off the mould.
Hence they are ~,~f~lably kept in a vertical position and the t~vo halves of the mould gently se~alated. To ~ n~ m~ging the gel structure, the top po~itioning guide should be removed before the removal of the mould halves but the bottom guide should remain in place.
(S) ~ gment~tion of the ~el ~h~l~hlre The moulded gel structure lerc.l~d to above c4..~ c of an outer hydrogel layer which is ~up~l~ed by and ~-~ .I.ic about an axial ~u~oll line.
.~m~ller discrete gel se~ P~t~ which remain ~u~lLed by the axial ~u~
line can be created by cutting the outer ccs--~..l~ic hydrogel layer in such a way that the axial line remains intact and sliding the cut segrnent along the axial line so as to form a space bet~veen the disc,~ete small gel segments. The above cut/slide operation may be ~lrollL~ed either before or after the concentric hydrogel layer has been dried and prior to Co~ting Huw~ver, it is generally easier to perform the cut/slide operation on wet hydrogel.
(i) The "long section" may be segm.onted into lengths, e.g. 10 mm, m~int~inP~ on the support line "6". The ~U~Ul led segments may then be dried and processed as required for specific applic~tions.
~WO 94/03159 21414 5 9 i pcr/Aus3/oo392 (ii) In an alternate emborliment, the core matri~ may be sectioned subsequent to drying but prior tO coating.
(6) Drying Depending on the molec~ r stability of the active cu~ oulld and speed of drying, the water based gel structure may be air dried under ambient con~itir)nc or at low te~ atures (e.g. at 2 C) by flllching with dry nitrogen gas. For ~ mrle, a gel structure CQ~ g about 10~o total dry matter takes 8-10 hours to dry the gel to a co~la,lt weight at room temperature (21 C).
The drying time will be appreciably longer at lower te~l alul es. The drying times are gel co~ o~ ion Clepen~ nt (7) (~o~tin~ of ~he (~Jt~ tllre (i) Once dried the gel structure mounted on the support may be re~cct~mhled with the 2 halves of the teflon mould of the same internal or dirrelc.,t internal (li~nnett~r to allow for the bioerodible outer co~ting to be ~rrliecl to the core. Thus, after the ca~ct is formed and dried, the dry cast may be coated with a water ;.,.~.~ .".eable co-polymer such as polylactic acid (pLa)/polyglycolic acid (p&a) (85:15) co-polymer to form a co~ting (ii) Alternatively the dried gel structure on the su~l l "6" may be coated by repeated dipping into a polymeric sohltion and drying to achieve a thin layer of a s~ "l i~lly water i~ ~eable coating with specific tl~S~ characteristics (refer to Fy~mple 3).
(iii) Alternatively the dried gel structure on the ~u~ "6" may be coated by repe~tecl ~Lyillg with a polymeric solution and drying to achieve a thin layer of a s~ st~nti~llywater impf-rme~ble coatingwith specific characteristics (refer to F~mrle 4).
Wo94/03159 ~,~4~4S9 PCr/AU93/00392 ~
(iv) Alternatively the dried gel structure on the support "6" may be coatedby repeated applir~tion of a polymeric solution via a "rod" or '~vick"
and drying to achieve a thin layer of a snhst~nti~llywater impermeable coating with specific 11 ~a~ characteristics (refer to F~mple S).
(8) ~ ce Profile Control For manip ll~ting the release characteristics, the release mode of the present device can also be modified by the cQn~e~ alion and com~osition of the matrix materials. For ~y~mrle~ when agar was used as the matrix material, the release was faster and the extent of release higher. This demonstrates the ability to affect the release rate by changes in matri~c composition. Variationsin~ lcle repl~çment of the water based hydrogel matrix with hydrophobic materials such as glycerol monoste~rate.
lS
l;XAlVl P~ .F. 1 - Fabrication of imrl~nt cu~ human serum albumin (HSA) andhnm~n IgG
This ~Y~mrle is illL~LraLi~.. of te~lature in~hl~ecl gelling and gives evidence of an 20 i ~ ogical les~ollse to an incc,l~l ated ~ntigen Flc;y~,~t;nn of Tmpl~nt 0.9 ml of HSA/hllm~n IgG soll~tion (9.5 and 5.8 mg/ml respectively in 0.1 M NaCl) 2S were miYed with O.S ml of 1~o NaCl solution and the mixture equilibrated to 43 C.
It was then mixed with 4.6 ml of gelatine/agar matri~c solution (13% and 1.3% w/v respectivel~, gel~tine, cell culture reagent from Porcine stein, approx 300 bloom, Si~na catalogue no. G1890) also equilibrated at 43C. The reclllt~nt mixture wasd to the mould assembly eguilibrated at 43C with a 7 mm internal 30 diameter x 20 mm long teflon mould and a 0.4S mm cli~meter ~" line as the centre ~uy~o- l. The inlets to the moulds were then stoppered and the moulds were allowed to e~uilibrate at 43C for 10-1S minlltes before the temperature of the ~O 94/03159 2 ~ 4 1 ~ 5 9 PCI /AU93/00392 , thermal jacket was slowly lowered to that of mnning cold tap water at about 20 C
over 20 mimlteS. The gel was then soliclified by cooling the mould assembly to 0 oc and m~il.t~ i..g it at that temperature for half an hour. After the mixture soli~lifiecl the moulds were r1icm~ntled and the gel structure on a string stretched in a bow was S removed carefully in a vertical orient~tion to avoid hc,l~ullLal splitting of the gel structure by the stretched ~u~ while the gel structure was still fragile. The gel structure ~UypOI led by the string ~up~ll in a bow were cut and separated in thecut/slide operation and air dried at room temperature overnight (about 18 hours).
The dried gel structures were then coated with a water based polyacrylic resin 10 Eudragit E 30D by five repeated cycles of dipping in an Eudragit suspension for 30 seconds and drying for 60 minlltes~ Eudragit E 30D is an aqueous dispersion of poly(meth)acrylic acid esters supplied by Rohm Pharma GmbH Weiterstadt Darmct~lt West Germany. When dry, the gel structures were dismounted from the bow and trimmed to se~m~-ntc of 1 cm length (diameter 3 mm). Each segrnent was 15 estim~terl to co.-l~;.. 0.051 of the original HSA/h-lm~n IgG antigen solution.
Placebo imrl~ntc were made in exactiy the same way as the antigen impl~ntc except that the HSA/hl~-n~n IgG sol-~tinn was replaced by 0.9 ml of 0.1 M NaCl.
20 Fv~ tinn nf Tmrl~nt Sheep previously ;~ cd with human serum were imrl~ntecl subcutaneously on the inside sulr~ce of hin-lle~c using a me~h~ni~l imrl~nt~r fitted with a 2.8 mln internal ~ met~r n~eclle- Two im~l~nt segm~ntc co..~ -g antigen or placebo were 25 given to each sheep.
To determine the antibody les~,.ce) blood s~mpl~s were taken from the sheep prior to receiving imrl~ntc and on days 9, 15 and 23 following impl~nt~tion. Sera wereobtained from blood s~mrles by standard sernlogit~l practice and assayed for 30 ql-~lit~tive and qll~ntit~tive antibody titres using double immllno diffusion and ELISA (Enzyme T.ink~l Tmmllno Sorbent Assay) te~hni~lues respectively.
2 ~ 4 '~ ~ PCr/AU93/00392 Rt~cnl~c Results of double immnno diffusion assay showed that there was an increase of antibody titre in recipients of the HSA/human IgG imrl~ntc but not in those of the 5 placebo. The increase in antibody titre was r~ .able to that obtained when norrnal immnnic~tion protocol with adjuvanted antigen ~us~nsion was used. As shown in Table 1, the le;,~ollse in general wac m~rim~l at day 9 of the four scheduled s~mrling days for both the specific anti-IgG and anti-HSA responses.
~ im~l increases at day 9 ranged from four to thirteen fold for anti-IgG re.,~l~sc 10 and seven to twent~five fold for anti-HSA. Titres were notably high relative to those in sheep receiving adjuvanted antigen suspensions, with amounts of specific antibodies approaching the highest that has yet been obtained from a few select sheep (that is in the order of 32 units of antibody in the sheep serum to either the HSA or human IgG). For three weeks following imrl~nt~tion, antibody titres 15 rem~inecl signifil ~ntlyhigh but decreased with time in the antigen imrl~nte~ ~nim~lc In addition to the at least equivalent 1 ~s~ es obta~cd, i l l l l l l ll i~ i.c~tion using antigen imrl~ntc can afford a ~lu~ber of other alY~tages. T...~ i.c~fion with imrl~nt.c was very simple to ~....1~,1l~ and cr....~.~lcd with the louLiL.c method far less time 20 co.. ~.. ing Apart from the puncture mark caused by the imrl~nt~r needle, no ulceration or swellingwas evident at the imrl~nt site. This is in sharp contract to the sitll~tion of rouli~e practices when ~nti~n ~u~ innc, especially those using Freund's adjuv~, are used for ;.~ ...ic~ti.m ~0 94/03l59 2 ~ 59 Pcr/Au93/oo392 TABLE 1 - Qll~ntit~tive Antibody Response by ELISA Method of Deterrr~ination Sheep Tmrl~nt Day O Day 9 Day 15 Day 23 No.
S Anti-IgG Re~ .se 7 Antigen 3.3 19.9 (6.0X) 15.2 (4.6X) 9.6 (2.9 X) 9 Antigen 1.7 1?.8 (10.SX) 14.0 (8.2X) 9.9 (5.8X) 3 Antigen 0.9 11.7 (13.0X) 8.9 (9.9X) 6.4 (7.1X) O Antigen 7.0 24.9 (3.6X) 28.3 (4.0X) 25.3 (3.6X) 8 Antigen 1.2 8,5 (7.1X) 6.9 (5.8X) 5.0 (4.2X) Placebo 2.0 2.0 (1.OX) 2.2 (1.lX) 2.1 (1.lX) 6 Placebo 4.8 8.8 (1.8X) 8.2 (1.7X) 6.1 (1.3X) 4 Placebo 3.9 4.1 (1.lX) nd- nd-Anti-HSA R~ se 7 Antigen 1.6 15.7 (9.8X) 13.2 (8.3X) 8.0 (5.0X) 9 Antigen 1.0 21.1X (21.1X) 19.4 (19.4X) 14.5 (14.5X) 3 Antigen 0.9 22.3 (24.8X) 20.6 (22.9X) 14.2 (15.8X) O Antigen 3.5 23.8 (6.8X) 26.6 (7.6X) 18.9 (5.4X) 8 Antigen 1.5 13.3 (8.9X) 12.2 (8.1X) 9.8 (6.5X) Placebo 1.0 0.9 (0.9X) 0.9 (0.9X) 0.9 (0.9X) 6 Placebo 4.9 6.4 (1-3X) 6.0 (1.2X) 5.8 (1-2X) 4 Placebo 1.7 1.5 (0.9X) nd- nd-nd = not det~ ~ Illilled; figures in brackets l~lesent the mllltirle increases over day O
WO 94/0315~ ~ 4~ 4S 9 PCr/AU93/00392 .F. 2 This ~ m~le is illustrative of chemical in~lllre~ gelling and is preferred for heat labile active material.
The ion in~ cerl gelling mould was assem~ed as described above (refer to Figure 1) and equilibrated at room tempelaLure. 7 ml of 3% w/w aqueous sodium ~lgin~te [Sigma Co. cat No. A-2033, alginic acid sodium salt medium viscosity, from M~rrocystic ~yl ;r~ (Kelp)] was mixed thoroughly with 7 ml of (~loctrit1illm nnvyi 10 toxoid at room te~ ature. The active ~uspel~sion was a concentrated solution of ~lnctrirlillm ~ toxoid cc~ llg the toxoid produced by the bacteria and 5.3 mg/ml of hydrated ~lllminillm hy~l~ide added as adjuvant. Although there is a slight increase in viscosi~y, the two ~ ion~ may be held at lower temp~ es (eg 4C) and mixed at lower telll~ldlL~es. The reslllt~nt mixture was transferred 15 with a syringe via the inlet port in the mould ~cc~mhly to fill the dialysis tube inside to a slight overflow from the ouclet bleeder hole with about 7 ml per mould. The two mould ~c.c~mhlies were ~i~.~ed into a bath of 500 ml aqueous AlCl3 sollltinn (0.5% w/w) at room tempe~a~ul. (or if desired at 1C) with continllQus slow ~git~tion using a m~gn~tic stirrer. Gelling was usually effected within 2-3 hours of 20 imm~orsinn but it is our nnrm~l practice to leave the gel structures to form for 4 hours. Following gel structure form~tion the moulds were removed from the gels in a vertical position The reslllt~nt gel structures were allowed to dry at room te~ dlule. When dry, the gels may be surface coated with Eudragit E 30D as previously described and/or reloaded with another layer of toxin ~Igin~te gel 2~ structure.
If desired sodium ~l~in~te may be directly ~lb~l;t~n~d by K-carrageenan but the tempelalule during filling of the tube mould needs to be higher to l~leV~llt premature gelling of the K-carrageenan.
Also if rapid gelling of the matrix active sollltinn is required, the gel inr~ ing agent, AlCl3, (e.g. 7 ml of 1.5% snllltinn) can be added directly to the 14 ml of the ~Igin~te ~Wo 94/03159 ~ 4 f 9 5 9 pcr/Au93/oo392 ~. n~vyi mi~ and the rtos..lt~nt solution mixed thoroughly and quickly.
l~XAlUP~ F 3 S This loY~rnrle illustrates the terhnique of dip coating of hydrogel irnplants and provides evidence of pulsatile release in vitro ev~ tion Polylactic acid (d,l-pLa) of inherent vi ,oosi~y (i.V.) = 1.0 dl/g (supplied by Boehringer Ingelheim) of mass 12 g wac dissolved in 120 ml of dichlorometh~n.o 10 Phosrh~te l~u~Lred saline (PBS), pH 7.2 was made accoldillg to the following recipe:
NaCl (80.00 g), KCl (2.00 g), 2HPO4.12H2O (15.36 g), KH2PO4 (2.00 g) dissolved in 1000 ml of lictilleri water.
The l~ ogd cores cQnt~ining red food dye or antigen were m~nllf~rtllred according 15 to the methodology described above using the cut/slide method.
Refel~g to Figure 2, dried hydrogel cores on the ~u~ line "6" attached to the spring steel bow "7" were dipped into the sollltirm of polylactic acid in dichloromçth~ne. Tmmersion time was 30 secon-ls for each coat. Upon removal from20 the polymer s~ ltion the excess polymer sollltir)n was allowed to run down the imrl~ntc and the hanger was then inverted to allow the polymer to run the other way: this aids in spreading the polymer evenly over the impl~ntc As illustrated in Table 2, groups were dipped either four times, i.e. 4 coats or si~c times, i.e. 6 coats.
At least one hour drying time was allowed bet~veen coats to ensure adequate drying 25 under the ~mbient conr~ on~. Individual cut impl~ntc were each placed in individual glass vials. PBS of volu_e 10 ml was added to each vial and they were placed in an incubator at 37 C. Molli~o~g wac carried out using U.V. visible spectroscopy tOme~cllre dye release into the solution.
S pcr/Au93/oo392 itions Number ofNumber of Coats T~ erature (C) pH
Sarnples 7 4 37 7.2 7 6 37 7.2 10 One sample commenced dye release early at day 4 and took 14 days tO attain 100%
release at day 18.
Of the rem~ining replicates mean release was at day48. The same impl~ntc attained a 100% release profile in an average of 5.3 days +/- 2.7 days. All s~mples 15 commPn~ecl dye release within a si~c day period bet~veen days 45 and 51. The total release time from when the first of the six impl~nt~ comm~n~ed dye release ( ~10%
release) to when the final imrl~nt reached 100% release was 14 days, i.e. from day 45 to day 59.
20 There appeared to be no st~tictic~lly signifir~nt ~lirrGlGnce between s~mrl~c with 4 coats and those with 6 coats. This is ~ ected as the pLa polymers are, in general, buL~c eroding thus are generally unaffected by sarnple thickn~ss The results show a ~ignifi~ ~nt delay in the time of onset of release of die comr~red 25 to uncoated s~mrl~s which gave 100% release within 3 hours of imrnersion in PBS.
F XA~IPF F. 4 - This ~r~mrle illustrates spray coating of hydrogel impl~nts and provides evidence of 30 pulsatile release from an in vitro eY~min~tion ~WO 94/03159 21414 S 9 PCr/AU93/00392 Polylactic acid (d,l-pLa) of inherent viscosity (i.v.) = 1.0 dl/g (supplied by Boehringer Ingelheim) of mass 12 g was dissolved in 120 ml of dichloromethane.
Phosphate buffered saline (PBS), pH 7.2 was made according to the following recipe:
NaCl (80.00 g), KCl (2.00 g), 2HPO4.12H2O (15.36 g), KH2PO4 (2.00 g) dissolved in 1000 ~nl of distilled water.
The hydrogel cores cont~ining red food dye or antigen were manufactured according to the methodology described above using the cut/slide method.
An ~tomicing spray nozzle connt~cted to a ~""u,essed air cylinder and to a 250 ml separating funnel which cont~ine~l the diLrerent polymer solutions was used to apply the polymer to the gelatine cores being rotated about the ~iU~ line using a "rotisserie" mech~nicm (refer to Figure 3). A polymer sol-ltion was sprayed onto the imrl~nt cores using air brush with a g~c ~lcs~ of 200 kPa and a ~lict~nce of 10-30 mm bclwcen the air brush outlet to the imrl~nt cores. The imrl~nt core string was hand rotated during Spl~yil~g in order to obtain .."ir~... co~ting. 65 ml of polymer solution was sprayed on a string of imrl~nt cores.
20 Referring to Figure 2, the position on the ~up~l line "6" of all imrl~ntc was noted, seven of those were selected at 1~dO1LI and their weights recorded. Tmrl~ntc ~vere placed in glass vials. PBS of volume 10 ml was added to each vial and they were placed in an ill~ubatol at 37 C and pH = 7.2. The d,l-PLA (iv = 0.1 dl/g) produced an opague papery coating which had a granular appearance. Despite their 25 appearance swelling without releace was ~ale"t from an early stage.
Results of the incubation work are given in Table 3. Seven imrl~nt.c were placed in individual s~mrle vials ront~ining 10 ml rhnsph~te buffer pH = 7.2 and incubatedat 37 C. MO~iLO1 illg was carried out using U.V. visible spc~ L~ osco~y to measure dye 30 release into the snlllti-~n One imrl~nt started to release on day 36, others started to release between days 73 and 79.
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This ~mple illustrates "rod coated" solvent based polymer app1ic~tion and provides evidence of pulsatile release in in vitro ev~ ,tion A method of coating gelatine cores was inv~stig~tecl to try to uve~rconle the difficulty of Cu~ lg the ends and edges of the core when spray co~ting A saturated -viscous5nl~1tion of polylactic acid (d,l-pLa) of inherent viscosi~y (i.v.) = 1.0 dl/g in dichloromethane (20% w/v) was made. Fu~ ore a co~ e;lecl series of gelatine 10 cores ~u~,uolled on an axial ~U~1~Ul~ was made using the cut/slide operation as described above. It was found that if one large viscuus drop of material was spread along a slowly rotating gelatine core (a~ tely 120 rpm), the drop rPm~ine~levenly dispersed and seemed to sllcce-ccfully ~ulloL~d the sharp edges and the end of the core (Fig. 4A). App1ic~ti-~n of the solvent based polymer was with a glass rod.
15 The rod is dipped into a viscous polymer so11ltion to pick up a small amount of material (Fig. 4B). The mateAal is then applied to one end of the gelatine core and drawn to the other (Fig. 4C).
Forty of these s~mrles were placed in a PBS, pH = 7.2, twenty at 37 C and twenty 20 at 50C. Results of the 50C appear in Table 4 and in Figures S and 6. Monitoring was carAed out using U.V. visible s~ osco~ to me~cllre dye release into the sollltion The 37C s~mrles had been in vitro for six~r dayc, the majority of which show no signs of release (Table 4).
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~WO 94/03159 ~2 1 4 1 ~ 5 9 PCI /AU93/00392 T;XAl~ F. 6 - This ~Y~mp1e shows the use of impl~ntc to obtain pulsatile release in ~nim~lc S An experiment was performed in which the delayed release from impl~ntc of tetanus toxoid was demonstrated by rletecting by ELISA antibodies produced by the mice in cs~ se to the released antigen.
Tmpl~ntc were made as described in Fs~m~le 4 except that 0.5 mg tetanus toxoid per 10 impl~nt was used as the active ingredient.
Antigens were used in impl~ntc with two coat cc,l~ ;tion.c and the control group (3) lcceived antigen in nnCo~te~ gelatine cores.
15 Mice were imrl~nteri sul~ t~.~eously on the inside sllrf~re of hind legs u~sing a mech~nic~l impl~nter fitted with a 2.8 mm internal diameter neerile~ One impl~ntse~m-ont co~t~i..i..g ~nti~n or placebo was given to each mouse.
To dete. ., . i . .ç the a l~ly r~ c, blood s~rnrles were taken intra-ocularly from 20 the mice prior to receiving impl~ntc and on days 14, 21, 36, 49, and 63 following impi~nt~tir)n Sera were ~ ed from blood s~rnrl.os by standard serological practice and assayed for qualitative and ql~ l;vt; antibody titres using double ;"""."~-- diffusion and ELISA (Ellzyme Linked Tmmllno Sorbent Assay~ techniques respectively.
FT T~S~ met~t~ri Nunc Maxisorp microtitre plates were coated overnight at 4C with the antigen ofchoice. Test serum was serially diluted on the plate to final dilutions in the range 800 30 to 25,600, and incubated at room te~l a~ , for one hour. Plates were washed and rabbit anlis.,. ~u to mouse i ., . ~ globulin~ conjugated with horse radish peroxidase, was added and incubated at room te.,~ alu~`e for one hour. Pero~ e activity was WO 94/03159 2~ ~145 9 PCr/AU93/00392 ~
~etectecl using 2,2'-a7ino-bis(s-ethylben7thi~7nline-6-sulphonic acid) (ABTS) substrate.
Evidence of seroconversion and thus of thè ~elease of antigen was any positive titre 5 (800 to 25,600) obtained.
The results given in Table S in~ir~te that the majority of ~nim~lc given uncoated s~mples showed serocollvclaion having been achieved within 14 days whereas nQ
seroco~ aion was observed with coated impl~ntc until 21 days. With imrl~ntc 10 coated with pLa homopolymer (i.v. = 1.0) se~oco~ .aion in all cases had not been achieved even after 63 days. That 100% serocc)~ .ion will result in all cases isinrlir,~te~l from the ol>s~,lvcd eventual scl~oco~ aion of all ~nim~lc treated with imrl ~ntc coated with 50:50 pLa/pGa (i.v. = 1.0). ~nim~lc receiving placebo imrl ~nt~
gave no antibody tire to Tetanus to~id.
TABLE S
Group No. of Coat cc~ ;on Serocollv~laion number (days) Mice 14 21 36 49 63 1 6 d~-pLa(i.v. = 1.0) 0/6 0/6 316 316 316 2 6 d~-pLa/pGa 0/S 2/5 5/5 5/5 5/5 (50:50; i.v. = 1.0) 3 4 no coat 2/3 213 3/3 ~13 313 3 5 placebo - no c,oat 0/S 0/S 0/S 0/S 0/5 Since mo-lifir~tionc withill the spirit and scope of the invention may be readily effected by ~l~Ol~S sldlled in the art, it ia to be understood that the invention is not limite(l to the particular embo-limrnt des~;libcdl by way of .oY~mplç, hereinabove.
~0 94/031S9 ~ 1 4 1 ~ 5 9 PCr/AU93/00392 REF~RENOES:
1. R. Jeyanthi and K. Pandurange Rao, "Controlled Release of Anti-Cancer Drugs from Collagen-Poly (HEMA) Hydrogel Matrices", Journal of S Controlled Release 13 (1990), 91-98.
2. Y.F. Maa and J. Heller, "Controlled Release of 5-Fluorouracil from Linear Poly (Orthoesters)", Journal of Controlled ~2ele~e, 13 (1990), 11-19.
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~ 94/031ss ~ 1 4 1 l 5 g PCr!AU93/00392 F XA~P~ F. S
This ~mple illustrates "rod coated" solvent based polymer app1ic~tion and provides evidence of pulsatile release in in vitro ev~ ,tion A method of coating gelatine cores was inv~stig~tecl to try to uve~rconle the difficulty of Cu~ lg the ends and edges of the core when spray co~ting A saturated -viscous5nl~1tion of polylactic acid (d,l-pLa) of inherent viscosi~y (i.v.) = 1.0 dl/g in dichloromethane (20% w/v) was made. Fu~ ore a co~ e;lecl series of gelatine 10 cores ~u~,uolled on an axial ~U~1~Ul~ was made using the cut/slide operation as described above. It was found that if one large viscuus drop of material was spread along a slowly rotating gelatine core (a~ tely 120 rpm), the drop rPm~ine~levenly dispersed and seemed to sllcce-ccfully ~ulloL~d the sharp edges and the end of the core (Fig. 4A). App1ic~ti-~n of the solvent based polymer was with a glass rod.
15 The rod is dipped into a viscous polymer so11ltion to pick up a small amount of material (Fig. 4B). The mateAal is then applied to one end of the gelatine core and drawn to the other (Fig. 4C).
Forty of these s~mrles were placed in a PBS, pH = 7.2, twenty at 37 C and twenty 20 at 50C. Results of the 50C appear in Table 4 and in Figures S and 6. Monitoring was carAed out using U.V. visible s~ osco~ to me~cllre dye release into the sollltion The 37C s~mrles had been in vitro for six~r dayc, the majority of which show no signs of release (Table 4).
W O 94/03159 2~4~59 26 - PC~r/A U93/00392 *
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~WO 94/03159 ~2 1 4 1 ~ 5 9 PCI /AU93/00392 T;XAl~ F. 6 - This ~Y~mp1e shows the use of impl~ntc to obtain pulsatile release in ~nim~lc S An experiment was performed in which the delayed release from impl~ntc of tetanus toxoid was demonstrated by rletecting by ELISA antibodies produced by the mice in cs~ se to the released antigen.
Tmpl~ntc were made as described in Fs~m~le 4 except that 0.5 mg tetanus toxoid per 10 impl~nt was used as the active ingredient.
Antigens were used in impl~ntc with two coat cc,l~ ;tion.c and the control group (3) lcceived antigen in nnCo~te~ gelatine cores.
15 Mice were imrl~nteri sul~ t~.~eously on the inside sllrf~re of hind legs u~sing a mech~nic~l impl~nter fitted with a 2.8 mm internal diameter neerile~ One impl~ntse~m-ont co~t~i..i..g ~nti~n or placebo was given to each mouse.
To dete. ., . i . .ç the a l~ly r~ c, blood s~rnrles were taken intra-ocularly from 20 the mice prior to receiving impl~ntc and on days 14, 21, 36, 49, and 63 following impi~nt~tir)n Sera were ~ ed from blood s~rnrl.os by standard serological practice and assayed for qualitative and ql~ l;vt; antibody titres using double ;"""."~-- diffusion and ELISA (Ellzyme Linked Tmmllno Sorbent Assay~ techniques respectively.
FT T~S~ met~t~ri Nunc Maxisorp microtitre plates were coated overnight at 4C with the antigen ofchoice. Test serum was serially diluted on the plate to final dilutions in the range 800 30 to 25,600, and incubated at room te~l a~ , for one hour. Plates were washed and rabbit anlis.,. ~u to mouse i ., . ~ globulin~ conjugated with horse radish peroxidase, was added and incubated at room te.,~ alu~`e for one hour. Pero~ e activity was WO 94/03159 2~ ~145 9 PCr/AU93/00392 ~
~etectecl using 2,2'-a7ino-bis(s-ethylben7thi~7nline-6-sulphonic acid) (ABTS) substrate.
Evidence of seroconversion and thus of thè ~elease of antigen was any positive titre 5 (800 to 25,600) obtained.
The results given in Table S in~ir~te that the majority of ~nim~lc given uncoated s~mples showed serocollvclaion having been achieved within 14 days whereas nQ
seroco~ aion was observed with coated impl~ntc until 21 days. With imrl~ntc 10 coated with pLa homopolymer (i.v. = 1.0) se~oco~ .aion in all cases had not been achieved even after 63 days. That 100% serocc)~ .ion will result in all cases isinrlir,~te~l from the ol>s~,lvcd eventual scl~oco~ aion of all ~nim~lc treated with imrl ~ntc coated with 50:50 pLa/pGa (i.v. = 1.0). ~nim~lc receiving placebo imrl ~nt~
gave no antibody tire to Tetanus to~id.
TABLE S
Group No. of Coat cc~ ;on Serocollv~laion number (days) Mice 14 21 36 49 63 1 6 d~-pLa(i.v. = 1.0) 0/6 0/6 316 316 316 2 6 d~-pLa/pGa 0/S 2/5 5/5 5/5 5/5 (50:50; i.v. = 1.0) 3 4 no coat 2/3 213 3/3 ~13 313 3 5 placebo - no c,oat 0/S 0/S 0/S 0/S 0/5 Since mo-lifir~tionc withill the spirit and scope of the invention may be readily effected by ~l~Ol~S sldlled in the art, it ia to be understood that the invention is not limite(l to the particular embo-limrnt des~;libcdl by way of .oY~mplç, hereinabove.
~0 94/031S9 ~ 1 4 1 ~ 5 9 PCr/AU93/00392 REF~RENOES:
1. R. Jeyanthi and K. Pandurange Rao, "Controlled Release of Anti-Cancer Drugs from Collagen-Poly (HEMA) Hydrogel Matrices", Journal of S Controlled Release 13 (1990), 91-98.
2. Y.F. Maa and J. Heller, "Controlled Release of 5-Fluorouracil from Linear Poly (Orthoesters)", Journal of Controlled ~2ele~e, 13 (1990), 11-19.
Claims (17)
1. A pulse release implant comprising:
an axial biodegradable core;
a first concentric layer comprising dehydrated hydrogel containing an active ingredient; and an outer coating, said outer coating being removable by the environment in which the implant will reside after administration.
an axial biodegradable core;
a first concentric layer comprising dehydrated hydrogel containing an active ingredient; and an outer coating, said outer coating being removable by the environment in which the implant will reside after administration.
2. A pulse release implant according to claim 1 wherein the hydrogel is selectedfrom gelatine, agar, alginates, carrageenan, gum gragacanth, acacia, and corn starch.
3. A pulse release implant according to claim 1 wherein the first concentric layer further includes one or more components selected from disintegrating agents, lubricants or osmotic modifiers.
4. A pulse release implant according to claim 1 wherein the active ingredient isa pharmaceutical substance.
5. A pulse release implant according to claim 1 wherein the pharmaceutical substance is an antibody, cytokine, growth promotant, hormones, cancer cell inhibitory molecule or agent, immune stimulant, and/or immune suppressant.
6. A pulse release implant according to claim 1 wherein the active ingredient isan antigen or an anti-microbial, anti-fungal or anti-viral agent.
7. A pulse release implant according to claim 1 wherein the active ingredient isa nutrient, vitamin or mineral.
8. A pulse release implant according to claim 6 wherein said antigen is an antigen from the clostridial family.
9. A pulse release implant according to claim 1 wherein the outer coating is formed from a material selected from modified starches, sugars, polyanhydrides, polyorthoesters, bioerodible polyesters and polylactic/polyglycolic acids.
10. A pulse release implant according to claim 9 wherein the outer coating is formed from polylactic/polyglycolic acids.
11. A process of preparing a pulse release implant including the steps of:
coating an axially disposed biodegradable core material with a hydrogel containing an active ingredient to form a concentric coating;
separating the coating into discrete segments disposed along the core material;
dehydrating the hydrogel;
coating the discrete segments with an outer coating, said outer coating being removable by the environment in which the implant will reside after administration;
and removing the exposed core material to obtain the pulse release implants.
coating an axially disposed biodegradable core material with a hydrogel containing an active ingredient to form a concentric coating;
separating the coating into discrete segments disposed along the core material;
dehydrating the hydrogel;
coating the discrete segments with an outer coating, said outer coating being removable by the environment in which the implant will reside after administration;
and removing the exposed core material to obtain the pulse release implants.
12. A process according to claim 11 wherein the separation step takes place before the dehydration step prior to coating with the outer coating.
13. A process according to claim 11 wherein the separation step takes place after the dehydration step prior to coating with the outer coating.
14. A process according to claim 11 wherein the outer coating is applied by forming said coating in a mould and subsequently removing said mould.
15. A process according to claim 11 wherein said outer coating is formed by dipping the hydrogel coated biodegradable core into a coating solution.
16. A process according to claim 11 wherein said outer coating is formed by spraying said hydrogel coated biodegradable core.
17. A process according to claim 11 wherein said outer coating is formed by application of the coating material to the hydrogel coated biodegradable core via a rod or wick.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPL387992 | 1992-07-31 | ||
| AUPL3879/92 | 1992-07-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2141459A1 true CA2141459A1 (en) | 1994-02-17 |
Family
ID=3776329
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002141459A Abandoned CA2141459A1 (en) | 1992-07-31 | 1993-08-02 | Controlled release implants |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0652745A1 (en) |
| CA (1) | CA2141459A1 (en) |
| WO (1) | WO1994003159A1 (en) |
| ZA (1) | ZA935569B (en) |
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| AUPM897594A0 (en) * | 1994-10-25 | 1994-11-17 | Daratech Pty Ltd | Controlled release container |
| WO1998055101A1 (en) * | 1997-06-04 | 1998-12-10 | Debio Recherche Pharmaceutique S.A. | Implants for controlled release of pharmaceutically active principles and method for making same |
| EP1112095B1 (en) | 1998-09-11 | 2002-11-20 | Gerhard Dr. Schmidmaier | Biologically active implants |
| US8784336B2 (en) | 2005-08-24 | 2014-07-22 | C. R. Bard, Inc. | Stylet apparatuses and methods of manufacture |
| US8388546B2 (en) | 2006-10-23 | 2013-03-05 | Bard Access Systems, Inc. | Method of locating the tip of a central venous catheter |
| US7794407B2 (en) | 2006-10-23 | 2010-09-14 | Bard Access Systems, Inc. | Method of locating the tip of a central venous catheter |
| EP2712547B1 (en) | 2007-11-26 | 2015-09-30 | C. R. Bard, Inc. | Integrated system for intravascular placement of a catheter |
| US9649048B2 (en) | 2007-11-26 | 2017-05-16 | C. R. Bard, Inc. | Systems and methods for breaching a sterile field for intravascular placement of a catheter |
| US10524691B2 (en) | 2007-11-26 | 2020-01-07 | C. R. Bard, Inc. | Needle assembly including an aligned magnetic element |
| US8849382B2 (en) | 2007-11-26 | 2014-09-30 | C. R. Bard, Inc. | Apparatus and display methods relating to intravascular placement of a catheter |
| US10449330B2 (en) | 2007-11-26 | 2019-10-22 | C. R. Bard, Inc. | Magnetic element-equipped needle assemblies |
| US10751509B2 (en) | 2007-11-26 | 2020-08-25 | C. R. Bard, Inc. | Iconic representations for guidance of an indwelling medical device |
| US9521961B2 (en) | 2007-11-26 | 2016-12-20 | C. R. Bard, Inc. | Systems and methods for guiding a medical instrument |
| US8781555B2 (en) | 2007-11-26 | 2014-07-15 | C. R. Bard, Inc. | System for placement of a catheter including a signal-generating stylet |
| US8478382B2 (en) | 2008-02-11 | 2013-07-02 | C. R. Bard, Inc. | Systems and methods for positioning a catheter |
| WO2010022370A1 (en) | 2008-08-22 | 2010-02-25 | C.R. Bard, Inc. | Catheter assembly including ecg sensor and magnetic assemblies |
| US8437833B2 (en) | 2008-10-07 | 2013-05-07 | Bard Access Systems, Inc. | Percutaneous magnetic gastrostomy |
| US9445734B2 (en) | 2009-06-12 | 2016-09-20 | Bard Access Systems, Inc. | Devices and methods for endovascular electrography |
| US9532724B2 (en) | 2009-06-12 | 2017-01-03 | Bard Access Systems, Inc. | Apparatus and method for catheter navigation using endovascular energy mapping |
| RU2691318C2 (en) | 2009-06-12 | 2019-06-11 | Бард Аксесс Системс, Инк. | Method for positioning catheter end |
| EP2517622A3 (en) | 2009-09-29 | 2013-04-24 | C. R. Bard, Inc. | Stylets for use with apparatus for intravascular placement of a catheter |
| US11103213B2 (en) | 2009-10-08 | 2021-08-31 | C. R. Bard, Inc. | Spacers for use with an ultrasound probe |
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| EP2575611B1 (en) | 2010-05-28 | 2021-03-03 | C. R. Bard, Inc. | Apparatus for use with needle insertion guidance system |
| EP2603145A2 (en) | 2010-08-09 | 2013-06-19 | C.R. Bard, Inc. | Support and cover structures for an ultrasound probe head |
| EP2605699A4 (en) | 2010-08-20 | 2015-01-07 | Bard Inc C R | Reconfirmation of ecg-assisted catheter tip placement |
| EP2632360A4 (en) | 2010-10-29 | 2014-05-21 | Bard Inc C R | Bioimpedance-assisted placement of a medical device |
| BR112013030348A2 (en) | 2011-07-06 | 2017-08-01 | Bard Inc C R | method for determining a length of a medical component for use with an ultrasound imaging system including a probe; method for determining a needle length by a needle guidance system; and needle length determination system for an ultrasound imaging device including an ultrasound probe |
| USD699359S1 (en) | 2011-08-09 | 2014-02-11 | C. R. Bard, Inc. | Ultrasound probe head |
| USD724745S1 (en) | 2011-08-09 | 2015-03-17 | C. R. Bard, Inc. | Cap for an ultrasound probe |
| US9211107B2 (en) | 2011-11-07 | 2015-12-15 | C. R. Bard, Inc. | Ruggedized ultrasound hydrogel insert |
| EP2861153A4 (en) | 2012-06-15 | 2016-10-19 | Bard Inc C R | Apparatus and methods for detection of a removable cap on an ultrasound probe |
| WO2015120256A2 (en) | 2014-02-06 | 2015-08-13 | C.R. Bard, Inc. | Systems and methods for guidance and placement of an intravascular device |
| FR3017533B1 (en) * | 2014-02-19 | 2016-03-11 | Cousin Biotech | IMPLANTABLE DEVICE, IN PARTICULAR FOR ABDOMINAL WALL REFECTION |
| US10973584B2 (en) | 2015-01-19 | 2021-04-13 | Bard Access Systems, Inc. | Device and method for vascular access |
| US10349890B2 (en) | 2015-06-26 | 2019-07-16 | C. R. Bard, Inc. | Connector interface for ECG-based catheter positioning system |
| US11000207B2 (en) | 2016-01-29 | 2021-05-11 | C. R. Bard, Inc. | Multiple coil system for tracking a medical device |
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| WO2020081373A1 (en) | 2018-10-16 | 2020-04-23 | Bard Access Systems, Inc. | Safety-equipped connection systems and methods thereof for establishing electrical connections |
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|---|---|---|---|---|
| US4434153A (en) * | 1982-03-22 | 1984-02-28 | Alza Corporation | Drug delivery system comprising a reservoir containing a plurality of tiny pills |
| JPS62120315A (en) * | 1985-11-20 | 1987-06-01 | Shin Etsu Chem Co Ltd | Production of sustained release tablet |
| US4716496A (en) * | 1986-05-09 | 1987-12-29 | Eaton Corporation | Panel-mounted control station housing |
| US4842867A (en) * | 1986-05-09 | 1989-06-27 | Alza Corporation | Pulsed drug delivery of doxylamine |
| DE3769707D1 (en) * | 1986-06-17 | 1991-06-06 | Recordati Chem Pharm | THERAPEUTIC SYSTEM WITH REGULATED DELIVERY OF ACTIVE SUBSTANCES. |
| US4961932A (en) * | 1987-10-26 | 1990-10-09 | Alza Corporation | Plurality of tiny pills in liquid dosage form |
| IL92966A (en) * | 1989-01-12 | 1995-07-31 | Pfizer | Dispensing devices powered by hydrogel |
| US5215758A (en) * | 1991-09-11 | 1993-06-01 | Euroceltique, S.A. | Controlled release matrix suppository for pharmaceuticals |
| WO1993017662A1 (en) * | 1992-03-02 | 1993-09-16 | Daratech Pty. Ltd. | Improved implants |
-
1993
- 1993-08-02 ZA ZA935569A patent/ZA935569B/en unknown
- 1993-08-02 EP EP93915569A patent/EP0652745A1/en not_active Withdrawn
- 1993-08-02 WO PCT/AU1993/000392 patent/WO1994003159A1/en not_active Application Discontinuation
- 1993-08-02 CA CA002141459A patent/CA2141459A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1994003159A1 (en) | 1994-02-17 |
| EP0652745A1 (en) | 1995-05-17 |
| ZA935569B (en) | 1994-04-12 |
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