CA1301572C

CA1301572C - Multi - unit delivery system

Info

Publication number: CA1301572C
Application number: CA000570389A
Authority: CA
Inventors: Patrick S.L. Wong; Felix Theeuwes; James B. Eckenhoff
Original assignee: Alza Corp
Current assignee: Alza Corp
Priority date: 1987-06-25
Filing date: 1988-06-24
Publication date: 1992-05-26
Anticipated expiration: 2009-05-26
Also published as: GB8814220D0; FR2617045A1; GB2206046B; AU1816988A; JPS6452457A; GB2206046A; ES2009014A6; IT1219401B; FR2617045B1; JP2732530B2; NZ225058A; DE3821424A1; IT8867602A0; DE3821424C2; AU602221B2

Abstract

ABSTRACT OF THE DISCLOSURE

A dispenser for use in a fluid environment which is capable of delivery of plurality of discrete drug containing units in any desired delivery pattern or profile.

Description

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Field of the Invention This invention relates to patterned drug delivery. More particularly, this invention relates to patterned drug dellvery by means of a plurality of individual drug delivery units or tablets. Still more particularly, but without limitation thereto, this invention relates to delivery of multi-agents orally or in other media in a pre-programmed delivery profi]e.
Definition of Terms The expressions "active agent" and "drug" are used interchangeably and as used herein broadly include any compound, composition of matter or mixture thereof, that can be delivered from the system to produce a beneficial and useful result. This includes pesticides, herbicicles, germicides, biocides, algicides, rodenticides, fungicides, insecticides, anti-oxidants, plant growth promoters, plant growth inhibitors, preservatives, antipreservatives, disinfectants, sterilization agents, catalysts, chemical rectants, fermentation agents, foods, food supplements, nutrients, cosmetics, drugs, vitamins, sex sterilants, fertility inhibitors, fertility promoters, air ~L3~ 3LS~7;~

purifiers, mlcro-organism a~tenuators and other ayents that benefit the environment of use.
The terms "active agent" and "drug" as used herein further includes any physiologically or pharmacologically active substance khat produces a localized or ~ystemic effect or effects in animals, including warm blooded mammals, humans and primates, avians, domestic household, spoxt or $arm animals such as sheep, goats, cattle, horses and pigs, or is administered to laboratory animals such as mice, rats and guinea pigs, to fish, reptiles, zoo and wild animals. The active drug which can be delivered includes inorganic and organic compounds including without limitation, those materials that act upon the central nervous system such as hypnotics and sedatives, psychic energizers, tranquilizers, anticonvulsan~s, muscle relaxants, antiparkinson agents, analgesics, antl-inflammatory, local anesthetics, muscle contractants, anti-microhials, an$i-malarials, hormonal agents including contraceptives, sympathomimetrics, diuretics, anti-parasites, neoplastics, hypoglycemics, nutritional, fa~s, ophthalmic, electrolytes and diagnos~ic ayents pharmacologically active peptides, protein anabolic hormones, growth promoting hormones related to the endocrine system, porcine yrowth promoting hormone, bovine growth promoting hormone, equine growth promo~ing hormone, ovine growth promo~ing hormone, human growth promoting hormone, growth promoting hormones derived by extraction and concentration f.rom pituitary and hypothalamus glands, growth promoting hormones produced by recombinant DNA methodsy polypeptides, growth hormone, somatropin, somatotropin, ': ' ,.,~
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somatomedin-C, gonadotropic releasing hormone, follicle stimulating hormone, luteinizing hormone, LH-RH, growth hormone releasing factor, gonadotropin releasing Eac~or, insulin, colchicine, chorionic gonadotropin, oxytocin, vasopressin, adrenocortico~rophic hormone, epidermal growth factor, prolactin, somatostatin, cosyntropin, lypressin, thyrotropin releasing hormone, thyroid stimulating hormone, secretin, pancreozymin, enkephalin glucagon. Histidine HCl is preferably mixed with somatropin.
The term "drug unit" as used herein includes units tha~
are capable of maintaining their physical and chemical integrity while housed within the dispenser. This includes, without limitation tablets with or without a density element; matrix tablets; capsules; elementary osmotic pumps, such as tha~
described in U.S. Pat. No. 3,845,770; mini osmotia pumps such as those described in U.S. Pat. Nos. 3,995,631, 4,034,756 and 4,111,202; and multichamber osmotic systems referred to as push-pull and push-melt osmotic pumps suah as those described in ' 2a ~l3~S~Z
~3- 67696-125 Jnited ~ta-tes Patent Nos. 4,320,759 and 4,449,983.
As used herein the expression "external fluid" includes water and other biological fluids.
- Background of the Invention The concept of patterned drug delivery covers a broad range of systems from time release capsules whose components have coatings which erode at different rates, to controlled release rate tablets which operate by osmosis.
Despite the development of the art however, there 10 remains a continuing need for improved methods and systems for providing controlled drug release profiles.
Summary of the Invention This invention seeks to provide sequentia:l timing and dispensing of delivery units containing the same or different active agents.
This invention also seeks to provide both a novel and useful agent formulation delivery system that is self-contained, self-powered, and also represents an improvement in the delivery art.
` ~ 20 These aims are demonstrated by the present invention which provides a drug dispenser for use in a fluid-containing environment comprising in combination: a rigid housing; a fluid activated driving member filling a portion of the space within said housing and being in contact with the housing; a plurality ` ~ of discrete drug units longitudinally aligned and contained within j;~ said housing, said units maintaining their physical and chemical :
integrity while contained within said housing; and a drug unit outlet means in said housing that communicates with the units.

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The inventlon also provides an active agent dispenser for use in a fluid-containing environment comprising, in combination:
a. a rigid housing open at one end to provide outlet means therefore, at least a portlon of said housing proximate the end o~
said housing opposite the outlet means permi~ting passaye of the fluid in said environmen~ to ~he in~erior of said housing;
b. a fluid actuated driving member within said housing in fluid transmitting relationship with ~he fluid passing poxtion of said housing proximate the end of said housing opposite said outlet means, said driving member, upon exposure of sai.d dispenser to said fluid environment, being the source of motive power for moving the contents of said houslng through said outlet; and c. a plurality of solid, dlscrete dosage units containing the active agent longitudinally disposed within said housiny between said driving member and said outlet mean~, whereby said dosage units will be sequentlally displaced from said housing in~o said ~luid environment hy said driving member upon exposure of said dispenser to said fluid environment, at least a portion of said dosage units being adapted to maintain their chemical and physical integrity while within the housinq and to dispense a substantial portion of their active agent content into the fluid environment after their displacement from sald housing into said environment.

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13~iS 7Z ARC 93 Brief Descri~tion of the Drawings 4 The invention will be described in further detail with reference to the accompanying drawings wherein:
6 Figure 1 is a partial cross-sectional view of the dispenser 7 of this invent~on, ~llustrating one embod~ment of the dispensing 8 configuratlon;
9 Figure 2 is a partial cross-sectlonal v~ew of the dispenser of th~s invent10n, illustrating a second e~bodiment of the 11 dispenslng configuration;
12 Figure 3 ~s a partlal cross-sect~onal view of the d~spenser 13 of th~s invent~on, ~llustrat~ng st~ll another embod~ment of the 14 dlspenslng conf~gurat~on;
Figure 4 ts a partial cross-sectional view of one embodiment 16 of the driving member for the dlspenser of this invent10n, 17 utilizing a hydrophilic expandable member;
18 Figure S is a part~al cross-sectional view of a second 19 embodiment of the driving member for the dispenser of this i~vention, utilizing an osmotically effective solute;
21 Figure 6 is a partial cross-sectional view of another 22 e~bodiment of the driving member for the dispenser of this 23 invention, utilizing an elementary osmotic pump;
24 Figure 7 is a partial cross-sectional view of another embodiment of the driving member for the dispenser of this 26 invention, utilizlng a gas generating composltlon; and 27 Figure 8 is a partial cross-sectional view of the dispenser 28 of this invention, illustrating another embodiment of the ~J~ ARC 93 L~ ~

1 dispensing configuration.

Description of the Preferred Embodiment 4 This invention can provide a variety of drug delivery ! 5 profiles including, but not limited to~ pulsed delivery of a 6 single drug or drug formulation, pulsed delivery of a sequence of different drugs or drug formulations, pulsed delivery of one drug 8 or drug formulation superimposed on continuous delivery of a g , differant drug or drug formulation, and simultaneous continuous delivery of several drugs or drug fo~mulations.
11 The drug dispenser of this invention i5 designed to deliver 12 a plurality of discrete longitudinally aligned individual drug 13 units by the l~near expansion of a fluid activated driving 14 nlember~ The drug units are such that they retain their physical and chemical integri~y while conta;ned with;n the system and do 16 not substantially commence delivery of active agent until after .~ .
17 they have been dispensed into the environment. It is comprised of 18 a dispensing component and a driving component, representative 19 embodlments of wh;ch are disclosed herein. F;gures 1, 2, 3 and 8 20 iilustrate various embodiments of the dispensing component 21 suitable for use in the dispenser of this invention. These ..
22 configurations can be combined with various embodiments of the 23 driving componen~, representative embodiments of which are 24 illustrated in Figures 4-7.
The dispensing and dri`ving componen~ designs are for use in a 26 fluid-containing environment and are merely exemplary of the 27 numerous embodiments suitable for use in this invention. The ~3~ '7~
1 portion of the housing adjacent to the dispenser component is 2 of a material which may be either semipermeable or impermeable to 3 the passage of external fluid. Typical suitable impermeable 4 materials include without limitation, polyethylene, polyethylene terephthalate (Mylar), plasticized polyvinyl chloride, metal-foil 6 polyethylene laminates, neoprene rubber, natural gum rubber and 7 Pliofilm (rubber hydrochloride). These materials are 8 additlonally flexible, ;nsoluble and chemically compatible with g the active agent contained in the units positioned therein, and, in the instance of prov~ding a drug or like depot within the body 11 of a living organism~ are biologically iner~, non-irritating to 12 body tissues and non-allergenic, Additional suitable materials include polystyrene, polypropylene, polyvinyl chloride, 4 reinforced epoxy res~n, polymethylmethacrylate, etc,, sheet metal 5 (e.g.9 aluminum~ copper, steel, etc.~, galvanized pipe, or 16 styren~e/acrylon;tr;le copolymer. Agaln, for drug depot 17 applications the same are advantageously biologically inert, non-18 irritating to body tissue and non-allergenic. Suitable 19 semipermeable materials include without limitation, all cellulosic polymers such as cellulose acetates, ethylcellulose, 21 methylcellulose, cellulose acetate butyrate, cellulose acetate 22 propionate, et~., or impePméable material blended with a 23 hydrophilic polymer or a low molecular weight water soluble 24 enhancer to render the material semipermeable.
Many other materials including those which are biologically 26 acceptable are suitable ~or fabrication of the impermeable 27 component of the device of this invention. While ~he impermeable 28 portion of the housing has previously been desc~ibed as being ~3~LS~;~

2 insoluble under the conditions and in the environment of intended 3 use, it is also within ~he scope of the invention that such 4 materials be insoluble only during the period of said intended use; thereafter dissolving or otherwise degrading into the 6 environment of the device. Thus, a dispenser is here contemplated 7 which is unaffected by its environment, solubility-wise~ at the 8 situs of us~, or which is only slightly soluble during the period g of intended use, such that once all the units have been dispensed, it will then dissolve or erode away, leaving no 11 objectionable residue or empty container at the said situs of 12 use.
13 The portion of the housing ad~acent ~o the driving component 1~ must be semipermeable so as to allow for passage of external fluid, since the driving member is fluid activated. Suitable 16 materials will be d;scussed at length with regards to specific 17 embodiments of the driving member.

18 The dispensing component shown in Figure 1 is comprised of a 19 rigid housing member 20. Housing 2n is also designed with an : ~ 20 outlet means, exit port 22. A plurality of movable discrete units 24~ 2fi, 28, 30 and 32 are aligned within the housing 20. This 2 configuration is merely illustrative and the dispenser may have numerous drug units in excess of the number shown in Fig. 1.
24 The drug units are in the form of a solid core, matrix table~ or in any o~ a variety of ~orms which are capable of ~air,taining their physical and Chemical integrity, i,e do not erode. The driving member 34 operates to displace the units towards the exit port 22, As unit 24 comes into con~act with the ~ t~ ARC 93 1 exit, it is dispensed into the environment and begins to deliver 2 drug in a controlled or semi-controlled fashion. Once unit 24 i;
3 dispensed, linear displacement pushes unit 30 through the housing so that it then comes into contact with exit 22 and is likewise dispensed. This continues until the dispenser is 6 depleted of drug units.
7 The units can provide a variety of drug delivery profiles 8 depending upon their composition. They can all contain the same 9 drug(s) at the same ooncentration(s) to deliver identical pulses of drug over time as each unit ;s dispensed or ~hey can contain 11 the same drug(s) at different concentrations to give dif~erent 12 pulses of drug. Alternately~ the units may contain d different 13 drug or drug formulat~or.
14 In the preferred embodiment, units 24, 26 and 28 contain a drug or drug formulation and alternate units 30 and 32 con~ain no L6 drug, such that when they are dispensed, an "off" period is 17 provided, during which time no drug is being delivered. The 18 additional advantage of this "alternating" configuration is that 19 once unit 24 is dispensed, the surface of unit 30 is exposed and may begin the erode. Having 30 as a non~drug containing unit 21 guar~ntees that the drug being delivered to the environment comes 22 from the dispensed-unit rather-than from the units still retained 23 within the housing.
?4 The dispensing conf;guration shown in Figure 2 is also designed to deliver a p1urality of discrete units to the 26 environment, and operates simila; to the embodiment of Fig. 1.
27 In Fig. 19 the geometry of the units permits close alignment so Z8 as not to have any space between adjacent units. This aspect is . ~

, ~30~ ARC 93 not critical to the effectiveness of ~he invention as is shown by Fig, 2 where the units are curved and therefore do not fit closely together within the housing~

The dispensing configuration of Fig~ 2 is comprised of a rigid housing 38 and a plurality o~ discrete drug units 40, 42 and 44, aligned therein. Three drug units are shown but in actual application, any number of units may be used. The driving member 46 displaces the units at the desired rate and dispenses them g individually through the exit por~ 48.
The units, 40 for example, can be elementary osmotic pumps Il or mini-osmotic pumps, for example. They can also be coated with a degradable coating to delay delivery until the units are actually dispensed into the envlronment.

The dispensing configuration shown in Figure 3 is comprised of a housing ~ember 50 and a plurality of discrete drug units 529 16 ~
54, 56 and 58 aligned therein. As with Figs. l and 2, the number of uni~s shown is merely illustrative and is not intended to limit the invention in any manner.

The driving member 60 operates to linearly displace the units and dispense them through the exit port 62, The units, 52 for example, are comprised of a plastic or polyethylene cap 64 with a drug mix~ure 66 compressed within. The units may be bowl-shaped as shown or they may be box-shaped ~o hold a larger quantity of drug.The units are separated by partitions ~8, 7~, 72 and 74, which can be a rigid solid or a gel. As the unit 52 is dispensed~ the drug mixture 66 is exposed to the environment (external fluid~ and is thus delivered. Subsequently the 13C~157Z ARC 93 1 partition 68 is dispensed through the exit port 62.
2 This dispensing configuration provides pulsed drug delivery.
3 As unit 52 is dispensed, a burst of drug is delivered which is 4 followed by another pulse when unit 54 is dispensed and so ~orth.
The units may contain the same drug in the same or different 6 concentrations, or different drugs. In this manner, any pattern 7 of delivery may be fashioned.
8 Example I
9 The dispenser of Fig, 3 is especially suited for trea~ment of helminth infections in ruminants, specifically cattle.
11 Depending upon the nature of delivery desired, several drug 12 formulations can be used in th~s dispenser.
13 A suitable drug formulat~on is compr~sed of about 80 weight 14 percent Hapadex~ whlch is an anthelmintic agent for cattle sold by Schering-Plough Corporation. About 0.5 grams of ~he 16 formulation 66 is compressed into cap 64. Units 54, 56 and 58 are 17 also filled with the drug formulation. ~owever, if an off period 18 is desired, units 52 and 56 can contain drug and the alternate 19 units 54 and 58 can be empty.
~ For fast pulse delivery of Hapadex~, the drug formulation is 21 100X drug. However, this system can be designed to provide a 22 short duration pulse where -thé drug formulation has a gas 23 generator contained therein. Especially sui~able is a formulation 24 comprised of about 80% Hapadex~ and 20% citric acid/sodium bicarbonate.
26 I~ a longer period of delivery is desired, a disintegrating 27 agent such as Ac-Di-Sol ~FMC Oorporati3n), otherwise known as .
28 croscarmellose sodium9 can be incorporated into the drug ' .

' ''"; , 13~ ARC 93 .' 1 formu1ation in an amount up to 20 weight percent.
For even longer duration of drug delivery, the drug for~lation can be 80~ Hapadex~ and 20% polymer, such as Polyox~
or hydroxypropyl methylcellulose.
; For rumenal systems, an important criteria is that the system remain in the rumen of an animal over a prolonged period of time~ This is accomplished by placement of a density element within the dispenser. The housing 50 itself, may be the density element, Alternately~ one o~ the par~itions9 74 for example, can act as the density element. In still another embodiment9 unit 58 can be a density element, placed so as to remain within the hous~ng S0 after all of the drug conta~ning units have been dispensed.

The denslty element suitable for use ;n the dispenser of this invention mus~ be dense enough to retain the dispenser in the rumen-re~icular sac o~ a ruminant. The presence of a density element allows the dispenser to remain in the rumen over a prolonged period of time rather than letting it pass into the alimentary ~ract and be eliminated therefrom. As the dispenser remains in the rumen, a beneficial agent can be delivered to the ruminant at a controlled rate over an extended period of time.

Generally, a density element will have a density of from about 0.8 to 89 or higher, with the density in a presently preferred embodiment exhibiting a specific gravity of from about 2.2 to 7.6. For the ruminants cattle- and sheep, it is presently preferred that the density element exhibit a density such that ` there is a resulting dispenser density of about 3. Materials that ~3~S~
6769~-125 have a density that can be used for forming a suitable density element include iron, iron shot, iron shot coated with iron oxlde, i.ron shot magn&sium alloy, steel, stainless steel, copper oxide, a mixture of cobalt oxide and i.ron powder, and the like.
Exemplary of drugs that are soluble or very soluhle in water and can be delivered by the dispenser systems of this invention include prochlorperazine edisylate, ferrous sulfate, aminocaproic acid, potassium chloride, mecamylamine hydrochloride, procainamide hydrochloride, amphetamine sulfate, benzphetamine hydrochloride, isoproterenol sulfate, methamphetamine hydrochloride, phenmetrazine hydrochloride, bethanechol chloride, metacholine chlorlde, piloca:rpine hydrochloride, atropine sulfate, methscopolamine bromide, isopropamide iodide, trid:lhexethyl chloride, phenformin hydrochloride, methylphenidate hydrochloride, and mixtures thereof.
Exemplary of agents that have limited solubility or are very slightly soluble, or insoluble in water and blological fluids that can be delivered by the dispenser systems of this invention include diphenidol, meclizine hydrochloride, prochlorperazine maleate, thiethylperazine maleate, anisindioine, diphenadione, erythrityl tetranitrate, digoxin, isoflurophate, reserpine, ; azetazolamide, methazolamide, bendroflumethiazide, chlor-propamide r tolazamide, chlormadinone acetate, phenaglycodol, allopurinol, aluminum, aspixin, methotrexate, acetyl sulfisoxazole, erthromycin, and mixtures thereof r steriods ineluding corticosteroids such as hydrocortisone, hydrocorticosterone acetate, cortisone acetate and triamcinolon~, ~ S ~ ARC 93 anhydrogens such as methyltesterone, esterogenic steroids such as 2 17 ~ ~estradiol, ethinyl estradiol9 ethinyl estradiol 3-methyl 3 ether and estradiol, progestational steroids such as 4 prednisolone, 17 ~ -hydroxy-progesterone acetate, l9-nor-progesterone, norethindrone, progesterone, norethynodrel, and the 6 likeO
7 The drug can also be in the various chemical and physical 8 forms such as uncharged molecules, molecular complexes, 9 ~pharmacologically acceptable acid addition and base addition 1~ salts such as hydrochlorides, hydrobromides, sulfate, laurylate, 11 palmitate, phosphate, nitrate, borate, acetate, maleate, 12 tartrate1 oleate and salicylate. For acidic drugs, salts of 13 metals, amines or organic catlons, for example quaternary 14 ammoniu~ can be used. Der;vatives of drugs such as esters, ethers 15 and am;des can be used alone or mixed wlth other drugs. Also, a 16 drug ~hich is water insoluble can be used in a form that on its 17 release from the dispenser, is converted by enzymes, hydrolyzed 18 by body pH or other metabolic processes to the original form, or 19 to a biologically active form.
The dispensing configuration of Figures 1J 2 and 3, can be 21 combined with ary of the driving members illustrated in Figures 22 4, 59 6, and 7, to provide a taiiored drug delivery system.
23 Figure 4 illustrates a driving member system 76 utilizing an 24 expandable driving member 78 comprised of an external fluid insoluble, external fluid swellable composition. Member 78 is 26 encased in housing 80 which is a semipermeable membrane 27 substantially permeable to the passage of an external fluid and i3 13~ ARC 93 1 substantially impermeable t~ the passage of any ingredients 2 contained in member 78. The driving member 78 is positioned 3 adjacent to one of the drug units a~ interface 82.
4 External fluid is imbibed through the housing 80 by the expandable hydrophilic member 78 in a tendency toward osmotic 6 equilibrium, to continuously swell and expand member 78. Member 7 78 expands while maintaining an intact immiscible boundary at 8 interface ~Z, defined by ~he surface oF drug uni~ 86 and g expandable member 78~
Expandable member 78 has a shape that corresponds to 11 internal shape of housing 80 and is preferably made from a 12 hydrogel composltion. The hydrogel composition is noncross-l~lnked 3 or optionally cross-linked and it possesses osmotic properties, 4 such as the abil~ty to imbibe an external fluid through semipermeable housing 80, and exhibit an osmotic pressure 16 gradient across semipermeable housing 80 against a fluid outside 17 the dispenser sys~em~ The materials used for ~orming the 18 swellable, expandable member 78 are polymeric materials neat, 3nd 19 polymeric materials blended wit~l osmotic agents that interact with water or a biolog;cal fluid, absorb the Pluid and swell or 21 expand to an equilibrium state. The polymer exhibits the ability 22 to retain a significant fraction of imbibed ~luid in the polymer 3 molecular structure. The polymers in a preferred embodiment are 4 gel polymers that can swell or expand to a very high degree~
usually exhibiting a 2 to 50 fold volume increase~ The swellable, 26 hydrophilic polymers, also known as osmopolymers, can be 27 noncross-linked or lightly cross-linked. The cross-links can be 28 covalent, ionic or hydrogen bonds with the polymer possessing the i 3~ ARC 93 ability to swell in the presence of fluid, and when cross-linked it will not dissolve in the fluid. The polymer can be of plant9 animal, or synthetic origin. Polymeric materials useful for the present purpose include poly(hydroxyalkyl methacrylate) having a molecular weight of from 5,000 to 5,000,000;
poly(vinylpyrrolidone) having a molecular weight of from 10,000 to 360,000; anionic and cationic hydrogels; poly(electrolyte) complexes; poly(vinyl alcohol) having a low acetate residual; a swellable mixture of agar and carboxyme~hyl cellulose; a swellable composition comprising ~ethyl cellulose mixed with a sparingly cross-linked agar; a water swellable copolymer produced by a dispersion of finely divided copolymer of maleic ~nhydride with styrene, ekhylene, propylene, or isobutylene; a water swellable polymer of N-vinyl lactams; swellable sodium salts of carboxyl methyl cellulose; and the like.
: 16 . Other gelable, fluid imbibing and retaining polymers useful for Forming the hydrophilic, expandable driving member 78 include pectin havlng a molecular weight ranging from 30,000 to 300~000;

polysaccharides suoh as agar, acacia, karaya, tragacanth, algins and guar; Carbopol acidic carboxy polymer and its salt derivatives; polyacrylamides; water swellable indene maleic anhydride polymers, Good-rite0 polyacrylic acid having a molecular weight of 80,000 to 200,000; Polyox~ polyethylene oxide polymers having a molecular weight of 100,000 to S,OOO,OOO;
starch graft copolymers, Aqua-Ke~p~ acrylate polymers with water absorbability of about 400 times its original weight; diesters of polyglucan; a mixture of cross-linked polyvinyl alcohol and poly(N-vinyl-2-pyrrolidone); poly~ethylene glycol) having a molecular weight of 4,000 to 100,000; and the like. In a preferred embodiment, the expandable member 78 is formed from poly~ers and polymeric compositions that are ~hermoformable.
Representative polymers possessing hydrophilic properties are known in U.S. Pat. Nos. 3,865,108, 4,002,173, ~; 4,207,893, 4,220,152, ~,327,725, 4,350,271 and in Sco~t et al.
"Handbook of Common Polymers", CRC Press, Cleveland, Ohio (1971).
The osmotically effective compound that can be blended homo~eneously or heterogeneously with the swellable polymer, to form a driving member, are the osmotically effective solutes that are soluble in fluid imbibed into the swellable polymer, and exhlbi~ an osmotic pressure grad.tent across the semipermeable housing 80 against an external fluid. Osmoti~ally effective `~ compounds are known also as osmagents. Osmotically effec~ive osmagents useful for the present purpose include maynesium sulfate, magnesium chloride, sodium chlorlde, lithium chloride, potassium sulfate, sodium sulfate, mannitol, urea, sorbitol, inositol, sucrose, glucose and the like. The osmotic pressure in atmospheres, atm, of the o~magents suitable for the invention wlll be greater than zero atm, generally from 8 atm up to 500 atm, or higher.
Representatlve materials for forming the semipermeable housing include without limitation, semipermeable homopolymers, ~ semipermeable copolymers, and the like. In On2 embodiment typical ; materials include cellulose esters~ cellulose monoesters, ; cellulose diesters, cellulose triesters, cellulosa ethers, and ~:

~3~ 7~:

cellulose ester~ethers, mixtures thereoF, and the like. These cellulose polymers have a degree of substitutionr D.S., on their anhydroglucose uni~ form greater than 0 up to 3 inclusive. By "degree of substitution" is meant the average number of hydroxyl groups originally present on the anhydroglucose unit that are replaced by a substituting group, or converted into another group. The anhydroglucose unit can be partially or con~letely substituted with groups such as acyl, alkanoyl~ aroyl, alkyl, alkenyl, alkoxy9 halogen, carboalkyl, alky1carbamate, alkylcarbonate, alkylsulfonate, alkylsulfamate, and like semipermeable polymer forming groups.

The semipermeable materi al s typi cal l y i ncl ude a mernber selected from the group consisting of cellulose acylate, cellulose diacy~ate, cellulose triacylate, cellulose acetate, cellulose diaceta~e, cellulose triacetate, mono-, di- and tri-cellulose alkanylates, mono-, di- and tri-alkenylates, mono-, di-and tri-aroylates, and the like. Exemplary polymers including cellulose ace~a~e having a D.S~ of 1.8 to 2.3 and an acetyl content o~ 32 to 39.9~; cellulose diacetate having a D.S. of 1 to 2 and an acetyl con~ent of 21 to 35%; cellulose triacetate having a D.S. of 2 to 3 and an acetyl content of 34 to 44.8% and the like. More specific cellulosic poly~ers include cellulose propionate having a D.S. of 1.8 and a propionyl content of 38.5X;

cellulose acetate propionate having an acetyl content of 1.5 to 7% and a propionyl con~ent of 39 to 42%, cellulose acetate propionate having an acetyl content of 2.5 to 3%3 an average propionyl con~ent of 39.2 to 45% and a hydroxyl content of 2.8 to ~3~
1 5.4~; cellulose acetate butyrate having a D.S. of 1.8, and acetyl 2 content of 13 to 15%, and a butyryl content of 34 to 39%;
3 cellulose acetate butyrate having an acetyl content of 2 to 4 29 5%, a butyryl con~en~ of 17 to 53%, and a hydroxyl content of 5 0.5 to 4.7~; cellulose triacylates having a D.S. of 2.9 to 3 such 6 as cellulose trivalerate, cellulose trilaurate, cellulose 7 tripalmitate~ cellulose trioctanoate, and cellulose 8 tripropionate; cellulose diesters having a 3.SI of 2.2 to 2.6 g such as cellulose d~succinate , cellulose dipalmita~e, cellulose dioctanoate, cellulose dicarpylate, cellulose propionate 11 morpholinobutyrate; cellulose acetate butyrate; cellulose acetate 12 phthalate; and the like; mixed cellulose esters such as cellulose 13 acetate valerate, cellulose acetate succinate, cellulose 14 propionate succinate, cellulose acetate octanoate, cellulose valerate palmitate, cellulose aceta~e heptonate, and the like.
; 16 Semipermeable polymers are known in U.S.Pat.No. 4,077,4079 and 17 they can be made by procedures described in "Encyclopedia o~
18 Polymer Science and Technolo~y", Vol. 3, pages 325-354, 19 Interscience Publishers, Inc., New York, (1964).
Addi~ional semipermeable polymers include cellulose 21 acetaldehyde; dimethyl cellulose acetate; cellulose acetate 22 ethylcarbamate; cellulose acetate methylcarbamate; cellulose 23 dimethylaminoacetate; a cellulose composition comprisin~
24 cellulose acetate and hydroxypropyl methylcellulose; a 25 composition comprising cellulose dcetate and cellulose acetate 26 butyrate; a cellulose composition comprising cellulose acetate 27 butyrate and hydroxypropyl methylcellulose; semipermeable 28 polyamides; semipermeable polyure~hanes; semipermeable ~3~ 67696-125 polysulfanes; semipermeable sulfonated polys~yrenes, crosslinked, selectively semipermeable polymers formed by the copreclpltation of a polyanion and a polycation as disclosed in United States Patent Nos. 3,173,876, 3,276,586~ 3,541,005, 3,541,006 and 3,546,1~2; selec~ively semipermeable silicon rubbers; semi-permeable polymers as disclosed by Loeb and Sourirajan in United States Patenk No. 3,133,132; semipermeable polystyrene derivatives; semipermeable (polysodiumstyrenesulfonate);
semipermeable poly(vinylbenzyltrimethyl) ammonium chlorlde;
semipermeable polymers exhibiting a fluid permeability of 10 to 10 7 (cc.mil/cm2hr-atm) expressed as per atmosphere of hydrostatic or osmotic pressure difference across a semiper~eable wall. The polymers are known to ~he art ln United States Patent Nos.
3,845,770, 3,916,899 and 4,160~020 and in J. R. Scott and W. J.
Rof~, "Handbook o~ Common Polymers", CRC Press, Cleveland, Ohio (1971).
Other materials that can be used to form the semi-permeable housing for imparting flexibility and elongation properties to the wall, for making the housing less to non-brittle and to render tear strength include phthalate plasticizers such as dibenzyl phthalate, dihexyl phthalate, butyl octyl phthalate, straight chain phthalates o six to eleven carbons, diisononyl phthalate, diisodecyl phthalate, and the like. The plasticizers include nonphthalates such as citric acid esters, triacetin, diocty~ azelate, epoxidized tallate, triisoctyl trimellitate, triisononyl trimellitate, sucrose acetate isobutyrate, epoxidized ~`

--3\ - 19 13C~1$72 ARC 93 soybean oil, and the like. The amount of plasticizer in the 2 housing when incorporated therein, is about 0,01 to 20X by 3 weight, or higher.
4 Figure 5 illustrates a driving member 88 utilizing an osmotically effective solute. The osmotically effective solute is 6 in solution 90 which is retained within a rigid housing 92 7 comprised of a semipermeable membrane substantially permeable to 8 the passage of an external fluid and substantially impermeable ~o g the passage of the osmotically effecttve solute contained in solution 90. The solution 90 is separated fro~ the drug units 94 11 for example, by mea~s o~ a ~lexible membrane 96.

12 The ability of driving member 88 to displace the drug units, 13 94 for example, housed within a dispenser depends upon the 14 osmotic pressure genérated by the solution 90 of the osmotically effective solute confined within housing 92. This solutior 16 exhibits an osmotiG pressure gradient against fluid in the 17 env;ronment into which the dispenser is placed, and is preferably 18 a saturated aqueous salt solution. To maintain the solu~ion l9 saturated. and therefore to achieve a constant osmotic pressure ~: 20 throuyhout operation of the dispenser, the housing containing the21 solution also contains excess solute in solid form, Various 22 osmotically ef~ecttve solutes can be used. These include 23 magnesium sulfate, magnesium chloride, sodium chloride, potassium 24 sulfate, sodium carbonaté, sodium sulfite, sodium sulfate, sodium bicarbonate, potassium acid phthalate, calcium bicarbonate, 26 potassium acid phosphate, raffinose, tartaric acid, succinic 27 acid, calcium succinate, calcium lactate and magnesium succinate.
2~ The excess solid solute can be in the form of dispersed particles 13C~ ARC 93 or preferably in the form of a pellet. The solution can initially be a solution of the same or of an osmotically effective solut~

different than the solid excess solute.

Figure 6 illustrates a driving member 98 which is similar in S
operation to that of Fig. 5. An elementary osmotic pump 100, such as that disclosed in U.S.PatONo. 3,845,770 is hel~ rigidly in place in the impermeable housing 102, being exposed to the environment at surface 104. External fluid is imbibed through the ' semipermeable wall 106 by the osmotically effective solute 108 contained within the pump 100. As the osmotic pressure within the pump 100 increases, solution (external fluid and osmotic solute) is forced through the ori~ice 110 into chamber 112, thereby exerting pressure on piston 114 which subsequently moves throu~h the hous~ng 102 to dispense the drug units 116 contained therein.
In order for this driving member to be operable9 the wall of the housing 102 im~ediately surrounding the pump 100, must be impermeable to the passage of fluid so ~hat external fluid does not enter chamber 112. Therefore, use of driving member 98 mandates that the housing be at least in part of an impermeable composition. In this manner, the housing in contact with the drug units can be semipermeable or impermeable.
Figure 7 illustrates a driving member 118 which operates by means of a gas generating composition 120. Housing 122 is made of a semipermeable material which is substantially impermeable to the passage of gas generating- composition 120, has a low permeability to the passage o~ an internally generated gas and is substantially permeable to the passage o~ an external fluid.

; ~3~1S ~Z ARC 93 1 Membrane 124 is made of a sem~p~ie~ e~ ~aterial which is 2 substantially impermeable to the passage of gas generating 3 composition 120 and substantially permeable to the passage of a : 4 generated gas. Its main function is to keep the gas generating composition 120 apart from the drug units contained in the 6 di spenser.
7 In operation, external fluid is imbibe~l through housing 122 8 to continuously wet and dissolve the gas generating compos;tion 9 120, causing i~ to react and produce a large volume of gas. This gas expands and passes through membrane 124, filling the area 11 126. This action correspondingly causes pressure to be exerted on 12 the drug unit 128 which thereby pushes this and the other units 13 conta~ned therein, through the housing 122.
,~ 14 Gas generating composit~on 120 cons~sts essentially of a dry 15 co~pound or an anhydrous mixture of compounds that when 16 intimately contacted by an external fluid that enters the housing ~: ~ 17 122, generates a gas that exerts a pressure to drive the 18 dispensing system. The composition 120 oomprises a preferably l9 solid aci~ic material, and a preferably solid basic material that :, ~
dissolve and react in the presence of fluid that enters the 21 housing 122. This composition may be in powder, crystalline, 22 granular or layered form. -Alternately, the gas generating 23 composition may be present homogeneously or heterogeneously 24 dispersed in a matrix. The matrix is a polymer permeable to the passage of external fluid and permeable to the passage of the ` 26 generated gas. The rate of gas generated in this embodiment is 27 governed by the rate of fluid passage through the polymer coupled 28 with the rate of fluid passage ehrough the housing 122. Sui~able ~3~
1 materials are disclosed in Theeuwes, U.S.Pat.No. 4,2031441 3 Another embodiment of the dispensing configuration o~ this 4 invention is illustrated in Figure 8. Thls embodiment is especially suited for delivery of units which all contain drug, 6 where it is deslred to prevent delivery from units which are 7 still contained w~thln the housing. The dispenser o~ Fig. 8 is 8 comprised of a rigid hous~ng member 13n which is des7gned with an outlet means, exlt port 132, A plurality of movable discrete units 134, 136, 138, 140 and 142 ar~ aligned with7n the housing 11 130, and are displac~d towards the exlt port 132 by means of 12 drlving member 144. The drug units ~re sim~lar in form to those 3 described ln reference to Fig. 1 but are all drug containing 14 units rater then drug- alterna~lng w~th non-drug containing units.
16 In Fig. 8, while the units are contained w~thin the housing 17 they are protected from exposure to the environmental fluld by 18 means of a plurality of plastic or polyethylene part~tions 146, 19 148, 150, 152 and 154. When the d~spenser is placed in the environment of use, the driving member 144 becomes fluid 21 activated and linearly dlsplaces the units, first dispe11ing khe 22 partition 146 and then unit 134. As unlt 134 is delivering drug, 23 unlt 136 is gradually belng displaced towards the éxit 132 and in 24 the meantime is protected from the environment by partition 148.
The amount o~ drug incorporAted in the units of the 26 dispenser of this invention varies wldely depending on the 27 particular drug, the deslred therapeutic effect~ and the time 1301~i ~Z
1 span for which it takes the drug to be released. Since a variety 2 of units in a variety of sizes, shapes and compositions are 3 intended to provide complete dosage regimes for therapy for a 4 variety of maladies, there is no critical upper limit on the amount of drug incorporated in the units of the dispenser. The 6 lower limit too will depend on the activity of the drug and the 7 time span of its release from the units. Thus, it is not 8 practical to define a range for the therapeutically effective 9 amoun~ of drug to be released by the individual units9 or the dispenser as a whole.
11 Th~s inven~ion has been described in detail with particular 12 reference to certain preferred embodirnents thereof, but it will 13 be understood that variations and modifications can be effected 14 within ~he spir~t and scope of the invention.

16 ..

Claims

1. A drug dispenser for use in a fluid-containing environment comprising in combination:
a rigid housing;
a fluid activated driving member filling a portion of the space within said housing and being in contact with the housing;
a plurality of discrete drug units longitudinally aligned and contained within said housing, said units maintaining their physical and chemical integrity while contained within said housing; and a drug unit outlet means in said housing that communicates with the units.

2. The dispenser of claim 1 wherein said plurality of drug units contain the same drug.

3. The dispenser of claim 2 wherein said drug units are separated by non-drug containing units.

4. The dispenser of claim 1 wherein said plurality of drug units contain different drugs.

5. The dispenser of claim 4 wherein said drug units are separated by non-drug containing units.

6. The dispenser of claim 1 wherein the portion of said housing in contact with said driving member is permeable to the passage of fluid.

7. The dispenser of claim 6 wherein said driving member comprises a fluid swellable composition.

8. The dispenser of claim 6 wherein said driving member comprises an osmotically effective solute.

9. The dispenser of claim 8 wherein said solute and said drug units are separated by a flexible membrane.

10. The dispenser of claim 6 wherein said driving member is a gas generating composition.

11. The dispenser of claim 10 wherein said gas generating composition and said drug units are separated by a semipermeable membrane.

12. The dispenser of claim 1 wherein the portion of said housing in contact with said driving member is impermeable to the passage of fluid.

13. The dispenser of claim 12 wherein said driving member comprises an elementary osmotic pump.

14. The dispenser of claim 13 wherein said elementary osmotic pump and said drug units are separated by a movable piston.

15. The dispenser of claim 1 which further comprises a density element.

16. An active agent dispenser for use in a fluid containing environment comprising, in combination:
a. a rigid housing open at one end to provide outlet means therefore, at least a portion of said housing proximate the end of said housing opposite the outlet means permitting passage of the fluid in said environment to the interior of said housing;
b. a fluid actuated driving member within said housing in fluid transmitting relationship with the fluid passing portion of said housing proximate the end of said housing opposite said outlet means, said driving member, upon exposure of said dispenser to said fluid environment, being the source of motive power for moving the contents of said housing through said outlet; and c. a plurality of solid, discrete dosage units containing the active agent longitudinally disposed within said housing between said driving member and said outlet means, whereby said dosage units will he sequentially displaced from said housing into said fluid environment by said driving member upon exposure of said dispenser to said fluid environment, at least a portion of said dosage units being adapted to maintain their chemical and physical integrity while within the housing and to dispense a substantial portion of their active agent content into the fluid environment after their displacement from said housing into said environment.

17. The dispenser of claim 16 wherein the portion of said housing adjacent to said dosage units is impermeable to the fluid in said fluid environment.

18. The dispenser of claim 16 wherein the portion of said housing adjacent said dosage units is permeable to the fluid in said fluid environment.

19. The dispenser of claim 16 wherein said housing is formed from a material permeable to the fluid in said fluid environment.

20. The dispenser of claim 16 wherein said active agent is selected from the group consisting of pesticides, herbicides, biocides, algicides, rodenticides, fungicides, insecticides, anti-oxidants, plant growth promoters, plant growth inhibitors, preservatives, antipreservatives, disinfectants, sterilization agents, catalysts, chemical reactants, fermentation agents, foods, food supplements, nutrients, cosmetics, drugs, vitamins, sex sterilization, fertility inhibitors, fertility promoters, air purifiers and microorganism attenuators.

21. The dispenser of claim 16 wherein said active agent is selected from the group consisting of human and animal hypnotics, sedatives, psychic energizers, tranquilizers, anticonvulsants, muscle relaxants, antiparkinson agents, analgesics, antiinflammatories, anesthetics, muscle contractants, anti-microbials, anti-malarials, hormonal agents, contraceptive agents, sympathomimetrics, diuretics, parisiticides, neoplastics, hypoglycemics, opthalmics, electrolytes and diagnostic agents.

22. The dispenser of claim 13 wherein the portion of said housing between said elementary osmotic pump and said outlet means is impermeable to the passage of fluid in said environment.

23. The dispenser of claim 22 wherein said active agent is selected from the group consisting of pharmacologically active peptides, protein anabolic hormones, growth promoting hormones related to the endocrine system, porcine growth promoting hormone, bovine growth promoting hormone, equine growth promoting hormone, ovine growth promoting hormone, human growth promoting hormone, growth promoting hormones derived by extraction and concentration from pituitary and hypothalamus glands, growth promoting hormones produced by recombinant DNA methods, polypeptides, growth hormone, somatropin, somatotropin, somatomedin-C, gonadotropic releasing hormone, follicle stimulating hormone, luteinizing hormone, LH-RH, growth hormone releasing factor, gonadotropin releasing factor, insulin, colchicine, chorionic gonadotropin, oxytocin, vasopressin, adrenocorticotrophic hormone, epidermal growth factor, prolactin, somatostatin, cosyntropin, lypressin, thyrotropin releasing hormone, thyroid stimulating hormone, secretin, pancreozymin, enkephalin glucagon, prochlorperazine edisylate, ferrous sulfate, aminocaproic acid, potassium chloride, mecamylamine hydrochloride, procainamide hydrochloride, amphetamine sulfate, benzphetamine hydrochloride, isoproterenol sulfate, methamphetamine hydrochloride, phenmetrazine hydrochloride, bethanechol chloride, metacholine chloride, pilocarpine hydrochloride, atropine sulfate, methscopolamine bromide, isopropamide iodide, tridihexethyl chlorlde, phenformin hydrochloride, methylphenidate hydrochloride, histidine hydrochloride, diphenidol, meclizine hydrochlorider prochlorperazine maleate, thiethylperagine maleate, anisindione, diphenadione, erythrityl tetranitrate, digoxin, isoflurophate, reserpine, acetazolamide, methazolamide, bendroflumethiazide, chlorpropamide, tolazamide, chlormadinone acetate, phenaglycodol, allopurinol, aluminum, aspirin, methotrexate, acetyl sulfisoxazole, erythromycin, hydrocortisone, hydrocorticosterone acetate, cortisone acetate and triamcinolone, 17.beta.-estradiol, ethinyl estradiol, ethinyl estradiol 3-methyl ether, estradiol, prednisolone, 17.alpha.-hydroxy-progesterone acetate, 19-nor-progesterone, norethindrone, progesterone, norethynodrel and mixtures thereof.

24. The dispenser of claim 23 which further comprises histidine HCl admixed with said somatropin.