CA2320728C - Absorbable copolymers and surgical articles fabricated therefrom - Google Patents

Abstract

A synthetic absorbable monofilament (16) comprising a glycolide, and an epsilon caprolactone is provided. The monofilament (16) exhibits physical characteristics equivalent to or superior than gut sutures.
The monofilaments (16) can be fabricated into a wide variety of surgical devices such as sutures and meshes.

Description

$URGICAL ARTICLES FABRICATED THEREFROM
TECHNICAL FIELD
Absorbable copoly,nie.rs of randomly polymer:i.zec). glycolide and caprolactone are described. Pr.ocesses for making the copolymers c-ind s>>rgi.ca]. articles in7de totally or in par.'t from such copolymers, including sutures, are also described.
BACKGROUND
Bioabsorbable surgical devices made from copolymers dertived from glycolide and epsilon-caprolactone are known in the art. Such bioabsor_bable surgical devices include surgical sutures.
A de<:ir.able ch.arGcteri; t=ic of a bioabsorbable suture is its ability to exhibit and maintain dc:sired tensile properties for a predetermined time period ' o.llowed by rapid absorption of the suture mass (hereinafter "mass los_" . }
Synthetic absozbable sutures are ;:nown in the art.
Absorbable multifi.lament sutures such as *DEXON sutures (made from glycolide homopolymer and commercial..ly ava;_? zb7.e from Davis & Geck, Danburv, Connecticut), *VICRYL sutures (made from a eopolymer of glycolide and lactide and commercially available from Ethicon, Inc.. So;nmerville, New Jersey) , and *pOLYSORB
sutures (also n!1de f_om a copolyme:- or glyco],ide anci 7.actide ancl coi'nmercial].y availlbze from United States Surgical Corporation, 39 Norwalk, Connecticut) are knoiv-n in t,ae industry as snorC term absorbable sutures. The classification short term absor_bable sutures generally.refers to surgical sutures which retain at least about 20 percer:t of their origi.nal strength ac three weeks aftc'r ].rnpIaI-Itation, w.i.t'-) Che JU1.1.11.C' bc:i.ng r_c~;cne.i ~l.l.y absorbed in the body within about GO to 90 clays port implantation.

*trade-mark -l-Long "irezm absorbable sutures are generally classified as sutures capable of retaining at least about 20 percent of their original strength for six or more weeks after implantation, with Lhe suture mass being essentially absorbed in 1~he body withi.n about 1.80 days post :i.mnl.r1ntal.:i.on. For example, *PDS II sutures (commercially available from Ethicon, Inc., Sommer_vi:1 J.e, New .7n.rsey) , are synthetic absorb-bl1-1 monof'ilament sutures ChZt reportedly retain at ].cast zbout 20 to 30 pcrcent-of its originsl sLrength six weeks. after implantation. I-Iowever., 18 PDS II reportedly exhibits minim2l mass loss until 90 days afL-er i--ipllntat.ion with the suture mass boin7 essentially zab:.orbed in thc body about 180 cia,Is after implantation. *MAXON suture (commerci,ally available from Davis & Geclc, Danbury, C'onncc:ticut) .is lnother, abcorbab].c synthetic mono:filarncnt t;hat: ronort:cdly generally fi.t:: th:i:: ah:;orption profile.
Most recenL-1y, United States Surgical Corporation has introduced *BIOSYN monofilament sutures which exhibit good flexibility, hlndling characteristics, knot strenqth and absorption characteristics similar to those of presently available shoz;t term absorbable multi_:EilamenL suture=:.
Another zttei,.pt to provide an acceraLable synt+het:i.c absorbabl.c monofi.1,.Zmer,L sutures resulted in *MONOCRYL, a suture fabricated from an absorbable block copol),-mer containg glycolide and caprolactone, commierciaily available from Ethicon, Inc. .
T-Iowevcr, no s vntheLic absorbable :nono:Cilament sutures ex:i,st Lod<<y which approximate the strength retention, mass 7.oss, and modulus of sutures ccmmonly referred to in the art as "catgut" or "gut" suL=ure,:. .Il: is well known in the ar.i- that the term gut sut+ur_c+ refers Co a collagen based suture of any Cype or origin oLten fabricated from the mammal ] an intestir.Cs, ~:uch as the serosal, lzyer of bovine intestines or the submucosaJ. fibrous lzyer of layer sheep intestines. GuL sutures exhib:.t the unique combinlti.on of two week strength retention Znd zibout 75 c3ay mass los<: whi.a.c cnairtt_aiTiinq accept=able modulus and LensiJ.e strength;
55 aT1C1 ~hll.'-', 'r1) e i=I1CJC?.y used in qynec"oioJ:i.cal nurgerV.

*trade-mark It would be advantageous to provide a synthetic absorbable suture which exhibits physical properties similar to the gut suture.
U.S. Patent No. 4,700,704 to Jamiolkowski does not teach that sutures can be fabricated from random copolymers of glycolide and epsilon-caprolactone, and more specifically from random copolymers containing from 20 to 35 weight percent epsilon-caprolactone and from 65 to 80 weight percent glycolide. Moreover, Jamiolkowski reports that sutures fabricated from glycolide/epsilon-caprolactone copolymers containing over 35% caprolactone under are not orientable to a dimensionally stable fiber. Jamiolkowski further reports that some sutures fabricated from glycolide/
epsilon-caprolactone copolymers containing 15% caprolactone are also not orientable to a dimensionally stable fiber.
Furthermore, Jamiolkowski also reports the undesirable combination of low modulus and low tensile strength for the glycolide/epsilon-caprolactone copolymers which he was able to fabricate into sutures.
Therefore, it would be unexpected that sutures made from random copolymer of glycolide and epsilon-captrolactone would provide the strength retention and mass loss characteristics approximating those of gut sutures while maintaining an acceptable modulus and tensile strength.
SUMMARY

It has now surprisingly been found that absorbable surgical articles formed from a random copolymer of glycolide and caprolactone exhibit strength retention, mass loss and modulus similar to that of gut sutures.
Preferably, the copolymers used in forming surgical articles include between about 25 and about 32 weight percent of hydroxy caproic acid ester units and between 75 and 68 weight percent of glycolic acid ester units.

In accordance with an embodiment of the present invention there is provided a suture fabricated from a random copolymer comprising from about 68 to about 75 weight percent glycolide and about 25 to about 32 weight percent epsilon-caprolactone, the suture exhibiting two week strength retention, mass loss of about 50% in 32 hours as measured in Sorenson's buffer solution at 80 C and a modulus ranging from about 150 kpsi to about 250 kpsi and a knot pull strength of about 1.7 to about 2.8 kg.
A further embodiment of the present invention provides for the use of such sutures for suturing a wound.
In a preferred embodiment the suture is a size 3/0 suture and exhibits a mass loss of about 50% after 32 hours in Sorenson's buffer solution at 80 C.
According to a particularly preferred embodiment, the suture is a size 3/0 suture and exhibits a mass loss of about 30% after 72 hours in Sorenson's buffer solution at 80 C.
In yet another preferred embodiment, the suture is a size 3/0 suture and exhibits a mass loss of about 12% after 120 hours in Sorenson's buffer solution at 80 C.

-3a-In pa.rticul.arly useful embodiments, the random copolymers can be spun into fibers. The fibers can be advantageously fabricated into either monofilament or muJ.tifilament sutures having physica]. properties similar to those of gut sutures.
In addition, a process of making such synthetic absorbable monofilament sutures from the above described caprolactone/glyco).ide random copolymers has been found. The process, for a given size suture, comprises the operations of 18 extruding the random caprolactone/glycolide copolymer at an extrusion temperAture of from about 70 C to about 21.5 C to provide a monofilament fiber, passing the solidified monofi].ament through water (or other suitabJ.e liquid medium) quench bath at a temperature of from about 15 C to about 25 C or through in air (or, other suitable gaseous medium) at from about 15 C to about 25 C, stretching the monofilament through a ccrie:c air ovenn at an overal}. stretch rar.io of r?'c71fl a}out 7:1 to about 14:1 to provide a stretched monofilament. In a particularly useful embodiment, the monofilament is stretched 28 through three air ovens by four godet stations. The first air ovcn is maintained at ambient temperature, whereas the second air oven is heated to a temperature above the crystalization temperature of the glycolide /epsilon caprolactone copolymer at about 80 C to about-. 110 C , and the third air oven is set at about 85 C to about 120 C. The draw ratio between the first and ,econd godet station ranges between about 5:1. to about 8:1. The draw ratio between the second and third godet station ranges between about 1.3:1 to about 1.8:1. The draw ratio between the third and fourth godet station ranges 38 between about 1.04:1 to about 1.06:1. The stuture then may be annealed with or without relaxation at a temperature of from about A0 C to about 120 C to provide the fini ,hec3 :;uture.

t':i.g. 1 is a schematic illustration of an apparal.t.t~ which :its :,ua.LAl.AL! Lo.17 martuf<ict-uriang of monofi.lament= ::utur.e:-, c7 i.:.:c:].c~;ed herein; .1i0 Vi.(J. 2 i:> tt pctrypective view of a suture attac:ltud t:c) Ft neeclle; .

3A-3C illustrate the form.ation of the lcuot:. wtii.ch wa3 employed in in the loop pull test used in Example 2.
pZLCRjPTION- _T-, r_ b E~I~Q~IN11-1e .[t: ha; been found that glycolide and epsiloncaprolzctone monomers can advantageously be combined to form a randorn copolymer usefu.l. :i.n f:or,ming s:ur.cli.c,ll, ar.ticJ.e, having ~-.trengt:h r.ct:rnt.iorr, inztss 1o:.;:., and modul.uw chlractera.st:ics similar to or. -,uner7.or to gut sutu.r.=c:~:.

'I'l~c.= r.,in<lr.,ni c':catxo.i.yniQJ: can he u:':.i.ttc,l c:cativotit:iona'1 techniqc.tca::.. x'or extimple, monomers can be dried, mixed in o re.xct:.ioit vt+:::,c;=i wJ.t.=.li . cn itii.tJ.ator (e:i.thc:r a :,a.ttc~le;
or multif=unc.ti.ona3. ina.t:i.ator) and a suitable polymerization cztnlyst-and heated at temperatures from about 170'C to about 200'C for a period of t-ime ranging from about 10 hours to about 30 hours.

The copol.ymer h,_ repeating units derived from g;l.ycolide randomly combi.necl with repeating units derived from caprolactone.
Repeating units derived from glycolide comprise between ccboue 25 tind aboia-. .i:? wci Jht: purc:c;nt of the copol.ymer. and pr.ef:er.ztb7.y cabout wc:igl=tt: pe:rcent of caprolactone and abouL 70 weight percent of gylcoa.idc.'. copolymers of caprolactone and glycolide havi.nr! an inher.ent_ vi.:;co:~it,y of from about 1.0 to about 1.8 hc/c7 meca:.uxed at 30 30'C und ..tt: a, concetrtration of 0.25 g/dl in chloroLor.rn or. ilr'I1' rnay generally be used.

r,utriotu i~ol,ul.ynu:r::: c:;jri br_ (ormcc3 :i.nt:o ii::iml my kiic,w>> t.%.~c.:1õnitauc:, .:uc:lt ..t:.:, J.ur u:~.anq)J.c:.
extrusion, tnoldinct and/or solvent ca::ting. The copo1.yinc:r:.: t:.act be uwoca .a.luttc:, 1-Aetuf.ed wit:li other absorbablc composit5.on::., or i.n combi.riation with non-absorbable componen.t:;. A wide vca.r.:i.ct;y nf c::LttI be iitanu,Eactured trom the copolymers;

described A"erein. These include but are not limited to clips and other fasteners, staples, sutures, pins, screws, prosthetic devices, wound dressings, drug delivery devices, anastomosis rings, and other implantable devices. Fibers made Erom the copolymers can be knitted, woveri or made into non-woven materials with other fibers, either absorbable or nonabsorbable to form fabrics, such as meshes and felts. Compositions including the::,e random copolymer s can also be used as an absorbable coating for surgical devices. Preferably, however, 18 the copolymers are spun into fibers to be used in making sutures.
Multifilament sutures of the present invention may be made by methods known in the art. Braid constructions such as those disclosed and claimed in U.S. Patent No.'s 5,059,213 and 5,019,093 are suitable for the multifilament suture of the present invention.
Fi,g. 1 substantially ii].uctrateC the extruding, quenching and stretching operations of the monofilament manufacturing operation herein. Extruder unit 10 is of a known or converit;ional type and is equipped with controls i:or regulating the temperature of barrel 11 in various zones thereof, e.g., progressively higher temperatures in three consecutive zoncs A, B and C along the length of the barrel.
Pellets or powder of resins of the present invention are introduced to the extruder through hopper 3.2. Any of the above described copoxymers which are useful for the formatiori of fibers can be used herein.
Motor-driven metering pump 13 delivers melt extruded resin at a constant rate to spin pack 14 and thereaftPr through spi.nncret 15 pos:ce;:;sing one or more orifices of desired diameter to provide a molten monofilament 16 which then enters quench bath 17, e.g., containing water, where the monofilament solidifies. The distance monofilament 16 travels after emerging froin spa.nnereL- 15 to Lhe point where iL enL-ers quench bath 17, i.e., the air gap, can vary and can advantageously be from about 0.5 to about 100 cm and preferab].y from about 1 to about 20 cm.
If desired, a chimney (not shown), or shield, can be provided to isolate monofilament 16 from contact with air currents which might otherwise affect the cooling of the monofilament in an unpredictable manner. in general, barrel zone A of the extruder can be maintained at a temperature of from about 170 C to 215 C, zone B at from about 1.70 C to 23.5 C and zone C at from about 1'70"C ro about 915"C. Additiona7. temperature puraihc:Cers inclucle: metering pump block 13 at from about 170 C to about 18 215 C, spinneret 15 at from about 170 C to about 225"C and quench bath at from about 15 C to about 40 C.
Monofi].ament 16 is passed through quench bath 17 around driven roller 18-and over idle roller 19. optionally, a wiper (not shown) may remove excess water from the monofilament as it is reinoved from quench bath 3.7. On exiting the quench bath the monofilament is passed through first godet station 1, which is equiped with five individual godets, i.e. godets 101, 102, 103, 104 and 105. Upon entering godet station 1, monofi.lament 16 is wrapped around a first godet 101 provided with nip roll 22 to prevent slippage which might otherwise result from the subsequent stretching operation; and subsequently passed over godet 3.01, under godet 102, over godet 103, under godet 104, and over godet 105 to godet station 2, containing godets 106, 107, 108, 109, and 3.10, where it is wrapped over godet 106, under godet 107, over godet 108, under godet 109, and over, godet 110..
Monofilament 16 passing from godet station 1 to godet station 2 is drawn through air oven 23 at a temperature ranging form about 20 C to about 30"C by the godets of godet station 2 which rotate at speeds faster than the speed of the godet station 1 to provide the desired draw ratio, which is from about 5:1 to about 10 :]. and preferably from about 6:1 to about 8:1, to eifect the molecular orientation of the copolymer from which it is fabricated and thereby increase its tensile strencrrh.
Following the initial draw at ambient temperature, monofilament 16 i: then subjected. to a second and a third.

drawing operation. Monofilament 16 is subsequently drawn from godet 105 through air oven 24, which in mai.ntai.ned nt: from about fio"C to ..ibotit: 7.].0"C:, t:n godet ::t:Zt.i.ail 3 r;otll::la.ty5.riji gotlut.:.~ 111.
112, 113, 114, and 3.15 where it is wrapped over godet 111, under godet 112, over godet 113, under godet 3.14, and over qodet 115.
Godel: : tation :") :spin:; faster than godet: station 2 to provide the desired draw ratio, which is from about 1.3:1 to about 1.8:1.
Monof:iJ;.unet,t, !.G a.cs UiGri drawn .Croin godct 115 t-hrouJh air oven 25, which is maintained at from about 85 C to about 120 C, by 18 godet station 4, conLaining godets 116, 117 118, 13.9, and 120 where it is wrapped over godet 116, under godet, 117, over godet 118, under godet 3.19, and over godet 120. Godet station 4 spins ta::Cer ttittn godet station 3 to provide the desired draw ratio, which is from about 1.05:1 to about 1.06:1. It should be understood that the godet arrangements in each of godPt;. stations 1, 2, 3, and 4, respectively should not be limited to the above described arrangement and that each godet station may have any suitable godet arrangement.
In an alternative operation for sutures for smaller 28 size sutures, sizes 4/0 to 8/0, monofi7.ament 16 is only passed through godet stations 1 and 2 and not subjected to any further stetching operations.
Annealing of the suture also may be accomplished with or without shrinkage of the suture. In carrying out the annealing operation, the desired length of suture may be wound around a creeJ, and the creel placed in a heatxnc7 c.ahi.nel; under nitrogen flow maintained at the desired temperature, e.g. about 70'C to about 120'C, as described in U.S. Patent No. 3,630,205.
nfter ft suit:able pera.od of residency in the heating c:crbinet, e.g., for up to about 18 hours or so, the suture will have undergone essent=inlly no shrinkage. 11s shown in U.S. Patent No.
3,630,205, the creel may be rotated within the heatinci cabinet in or.cier to i.rir;u.re unif=or.m heating of t_he monof:il.amrr,t= or the c:abiri4t ,nrxy be uf t:hc circulating hoL air lype in whieh case uniform ?teati.nq c,f th(-- monofilamc~nt wi 1 7. he: iir.hi.cvrcl wii'licm1.:
the need to rotgte the creel. Thereafter, the creel with its annealed suture is removed from the heating cabinet and when returned to room temperature, the suture is removed from the creel, conveniently by cutting the wound monofiilamQnt at opposite ends of the creel. The annealed sutures, optionally attached to surgical needles, are then ready to be pAckaged and sterilized.
Alternatively, the suture may be annealed on line with or without relaxation. For relaxatiori, the fourth godet station 1A rotates at a slower speed than the third godet station thus relieving tension on the filament.
The suture disclosed herein, suture 101, may be attached to a surgica], needle 100 as shown in Fig. 2 by methods well known in the art. Wounds may be sutured by pas}ing the needled suture through tissue to create wound closure. The needle preferably is then removed from the suture and the suture ti.cd.
it is further within the scope of this invention to incorporate one or more medico-surgically useful substances into the present invention, e.g., those which acce].erate or benef ic: i,a].ly inodil:y the healing proce:;4; when par. tic:l,us are applied to a surgical repair site. So, for example, the suture can carry a therapeutic agent which will be deposited at the repair site. The t'herapeutic agent can be chosen f.or its antimicrobial properties, capability for promoting repair or reconstruction and/or new tissue growth. Antimicrobial agents such as broad spectrum antibiotic (gentamycin sulfate, erythromycin or derivatized glycopeptides) which are slowly released into the tissue can be applied in this manner to aid in combating clinical and sub-clinical infections in a tissue repair site. To promote repair and/or tissue growth, one or several growth promoting factors can be introduced into the sutures, e.g.,.fibroblast growth factor, bone growth 1=actor, c:pidurinttl growLh f'rzctor, platelet derived growth factor, macrophage derived growth factor, alveolar derived growth -g..

factor, monocyte derived growth factor, magainin, and so forth.
Some therapeutic indications are: glycerol with tissue or kidney plasminogen activator to cause thrombosis, superoxide dimutase to scavenge tissue damaging free radicals, tumor necrosis factor for cancer therapy or colony sl=imulati.ng factor and interferon, interleukin-2 or other lymphokine to enhance the immune system.
It is contemplated that it may be desirable to dye the sutures of the present invention in order to increase i9 visibility of the suture in the surgica], field. Dyes known to be suitable for incorporation in sutures can be used. Such dyes include but are not limited to carbon black, bone black, D&C Green No. 6, and D&C Violet No. 2 as described in the hzndbook of U.S. Colorants for Food, Drugs and Cosmetics by i5 Daniel M. Marrion (1979). Preferably, sutures in accordance with the invention are dyed by adding up to about a few percent and preferably about 0.2% dye, such as D&C Violet No.
2 to the xesin prior to extrusion.
In order that those skilled in the art may be better 20 able to practice the compositions and methods described herein, the following example is given as an illustration of the preparation of random copolymers as well as of the preparation and superior characteristics of sutures made from the random copolymers. It should be noted that the invention is not 25 limited to the specific details embodS.ed in the examn.los and further that all ratios or parts recited are by weight, unless otherwise indicated.

38 Dry glycolide (4200 grams) and undistilled epsilon-caprolactone were added to a reactor aJ.ong with 0.35 grams of dxstil.l.c d tf.lnnous octoate and 3 grams of 1,6 hexaneclioJ.. The mixture was dried for about 48 hours with agitation under flow of nit:.r.ogun. '!'he rcactor temperaCure was then set at 100'C.
35 When the temperature of the reactants reached 100'C the temperature- was maintained for about 15 minutes at w}iich point the temperature of the reactants was raised'to about 1506C and the reaction vessel heated for about an addi.tional. 15 minutes.
The temperature of the reactants was then raised to about 190'C
and polymerization conducted with stirring under a nitrogen attnosphero for about 18 hours. The reaction product is then isolated, comniinuted, and treated to remove residual reactants using known techniques. The treatment to remove residual reactants occurs at 130'C for 48 hours under vaccuum.
ie Table I below sets forth typical conditions for extruding, stretching of size 3/0 sutures in accordance with this invention. All of the monofilament sutures were fabricated from the resin of Example 1.

CONDITIONS OF MANUFACTURING VARIOUS SIZES
OF MONOFILAMENT OF THE PRESF=NT INVENTION
Ex ip1e 1 St ire Size 3/0 P~- :)ce ,s Conditi.on:: Extriision extr.2der screw, rpm ?
putn. rpm 15.4 dr- en roller, mpm 2.7 br~ -zel temp., C, zone A 183 b:.:rel temp., C, zone B 186 b:.rrnl temp., C, zone C ].R9 clamp temp., 'C, 1.88 adaDter temp., 'C 189 put=p temp., 'C 196 b?_.)ck temp., 'C 190 barrel melt temp., 'C 192 pump melt temp., 'C 191 spinneret melt temp., 'C 194 barrel pressure, psi 1040 pump pressure, psi 1000 spir.nerer pressure, psi 1400 purr.n size, cc per revolution 0.16 diameter of spinneret, orifices, mm 1.2 no. of spinneret orifices 1 quer:,,h bath temp., 'C 20 Stretching (Orienting) Operation . arn g draw bath tenip., 'C ambient first godet station, mpm 2.9 second godet, mpm 20.8 thi.rd. godc+l. inpin 34.6 fourth godet station,mpm 36.2 first oven temp, 'C 28 second oven Cemp,'C 85 third oven t.emp, "C 90 overall draw ratio 12.57:1 Annealing OperaL=ion 1;X~.tmr~7.e 7annealing temp., "C FO'C
time (hrs.) 6 The phy:;:.cal pr.ope.rti.e~; of i,nc and l:hc,-, pr. c~C:cdux<~:: c:mp i oyed L'or their measuTetnCnt. are seC .Lorth in Table ii, as follows:

TASrjI? '1'I

PROCEDURES FOR MEASURING PHYSICAL PROPERTIES
OF MCNOT'ILANENT SUTURES OF THE PRESENT ZNVENTION
Phys.i.cn]. Pr oF>r_ rty Te2; L P:: ac:c.dur. c knot-pull strength, kg *U.S.P. XXI, tensile strength, sutures (881) straic7ht--pull strength, kg *ASTM D-2256, Instron Corporation elongation, v ASTM D-2256 tensile strength, kg/m.m2 ASTM D-2250", Instron Corporation Series IX Automated Materials Testing Syste:n 1.03A

Young's ?-Iodulus *Instron Merlin Software version 2000 Serie: IX calc:ulation 15.3 (commercially avz:i.lable from Tnstron Cor_porat_i.on) Table III below sets .f-orth the physical properties of 18 l:I:e size 3/0 ,;utux'e of the rDre~=cnt inve~n-. ~on.

*trade-mark TAME III
Physical Property Example 1 diameter (mm) .29R
knot-pull strength (kg) 2.66 Young's Modulus (kpsi) 7.70 Elongation % 22 Tensile Strength (kpsi) 102.2 As the data in Tables III illustrates, the suture made of the copolymer provided herein shows a desii=ed physical properties, such as modulus and tensile strength.

Example 2 ~~~~nL='~L'~iIrr 18 Monofilament sutures manufactured in accordance with the above described process using the copolymer of Example 1 were tested for in vitro strength retonta.on. In vitro loop-pull strength retention is indicative of in vivo strength retention. The in vitro strength retention of the suture was tested as follows:
To sitf1i7latE in vivo conditions, l:he SU l:ure r:r.lilipl '4' z werc stored in a container filled with Sorenson's buffer solution at 37"C. After various periods of time, the suture samples were t.Ilon removed f=rom the contaaner to test their loop-pull strength as follows. A knotted loop was formed.in a test suture in three steps as shown in FIGS. 3A - 3C. As shown in stFp 1 of of i~tG 3A , each suture was given tl douta'Le throw (left over right ) around a 2 cm diamater cylinder. In Stop 2, the free ends of the suture were set in a single throw throw (right over left) onto the initial throw of rct-c-p 1.
Fiu<<lly, , in ;::t;ep 3, another double throw (;lof t ovor right) was set onto the single throw of Step 2 to complete the knot.

The free ends of the suture were cut to approximately 0.5 inches and the loop was carefully erased f:roin the cyJ. i.nder. .
Testing of the loop was carried out useing an Instron Corporation (Canton, Mass.) Tensile Tester Model No. 4307, operated with a crosshead speed of. 51 mm/min and equipped with flat grips, each having a pin over which the loop is posi t ioned .
The results of the tests are presented in Table IV
hereinbelow. In the strength retention data reported in Table l8 IY, Tn represents the time elapsed in weeks since Che sample was placed in the solution, with n zepresenti.ng thc number of weeks.

TABLE ?V
PMtCWiMl; or IN VITRO STRrdaC7'{t rJsPnINf'~.1) COMMSI7'ION Tl R'2 T3 T4 T6 T11 Z'10 'ri r=.xnrtrra: T 44 71 0 -IN VITRO MASS LOSS
MonoFi.lament sutures manufactured in accordance with the above described process using the copolymer of Example 1 were tested for in vitro mass retention. In vitro mass retention str.cnc7tn is inc3ica1.i.ve of in vivo mas:: retention. The in vitro strength retention of the suture was tested as follows:
To simulate in vivo conditions, the suture samples were stored in a container filled with Sorenc:on's buff.r:r %:o].ution at 80'C. After various periods of, time, the sutur.e ~amples were then removed from the container filterred, rinsed with distiioled water and dried for about 6 hours at about 40'C
under vaccum and subsequently weighed.
The results of the tests are presented in Tablc V
herrinbc'low. Tn Lhe strength reteiition data report:ec1 in Table V, Tn represents the time elapsed in hours since t:he sample was placed in the solution, with n representing thc number of hours. It is well known in the art that one hour of immersion in the the container filled with Sorenson's buffer solution at 8o'C approximates about one week of invivo mass loss. For comparison purposes, the same cests were conducted on Monoczyl sutures.
All comparattive tests were performed on size 3/0 suLures.
TABLE
ie MCT1Urf3L OF z1V vI7'RO MAS,r, RCTnYNM
COME'o.SITION T2 T2 T3 I'4 T6 TH T10 Tl:
[JNMPT.Ii T 92.79 66.35 51 37.73 34.3]. 29.35 26.97 23.:
Mnllocryl 74,86 74.79 fifi.A3 47.95 47.G3 35,31 32.1/1 27.3 Modifications and variations of the compositions and processes disclosed herein are possible in liQht of the above teachings. It is therefore to be understood that changes may be made in particular embodiments described which are within the fuI], intended scopo of the invention as defined by the claims.

Claims (12)

CLAIMS:

1. A suture fabricated from a random copolymer comprising from about 68 to about 75 weight percent glycolide and about 25 to about 32 weight percent epsilon-caprolactone, the suture exhibiting two week strength retention, mass loss of about 50% in 32 hours as measured in Sorenson's buffer solution at 80°C and a modulus ranging from about 150 kpsi to about 250 kpsi and a knot pull strength of about 1.7 to about 2.8 kg.

2. The suture of claim 1, wherein the random copolymer comprises about 30 weight percent epsilon-caprolactone and about 70 weight percent glycolide.

3. The suture of claim 1, wherein the suture is a size 3/0 suture and the modulus is about 170 kpsi.

4. The suture of claim 1, wherein the suture is a size 3/0 suture and the knot pull strength is about 2.6 kg.

5. The suture of claim 1, wherein the suture is a size 3/0 suture and has a tensile strength of about 102 kpsi.

6. The suture of claim 1, wherein the suture is a size 3/0 suture and exhibits the following characteristics:
modulus about 170 kpsi knot pull strength about 2.6 kg tensile strength about 102 kpsi.

7. The suture of claim 1, further comprising a medico-surgically useful substance.

8. The suture of claim 1, wherein the random copolymer possesses an inherent viscosity of about 1.0 to about 1.8 dl/g at 30°C and a concentration of 0.25 g/dl in hexafluoroisopropanol (HFIP).

9. The suture of claim 1, wherein the suture is a size 3/0 suture and exhibits a mass loss of about 50% after 32 hours in Sorenson's buffer solution at 80°C.

10. The suture of claim 1, wherein the suture is a size 3/0 suture and exhibits a mass loss of about 30% after 72 hours in Sorenson's buffer solution at 80°C.

11. The suture of claim 1, wherein the suture is a size 3/0 suture and exhibits a mass loss of about 12% after 120 hours in Sorenson's buffer solution at 80°C.

12. Use of the suture of any one of claims 1 to 11, for suturing a wound.