Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/78—Preparation processes
  • C08G63/82—Preparation processes characterised by the catalyst used
  • C08G63/823—Preparation processes characterised by the catalyst used for the preparation of polylactones or polylactides
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L17/00—Materials for surgical sutures or for ligaturing blood vessels ; Materials for prostheses or catheters
  • A61L17/06—At least partially resorbable materials
  • A61L17/10—At least partially resorbable materials containing macromolecular materials
  • A61L17/12—Homopolymers or copolymers of glycolic acid or lactic acid
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/04—Macromolecular materials
  • A61L31/06—Macromolecular materials obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
  • C08G63/08—Lactones or lactides

Definitions

• the present invention relates to glycolide and dl - lactide based copolymer compositions and more particularly to crystalline copolymer compositions comprising less than sixty-two weight percent or less glycolide and methods of producing such compositions which are useful in the manufacture of absorbable medical devices.
• Copolymers of, and surgical devices made from dl-lac ⁇ tide and glycolide are well known.
• U.S. Patents relating to such copolymers and the like include: 3,620,218; 3,636,956; 3,9102,497; 3,918,455; 3,937,223; 4,137,921; 4,157,437; 4,243,775; 4,443,430; 4,835,139; 5,013,553; 5,198,220; 5,242,910; 5,229,469; 5,317,065; 5,320,624; 5,384,133; 5,395,747; 5,403,713; 5,425,984; 5,431,679; 5,439,884 and 5,470,340.
• the present invention provides novel compositions made of approximately sixty-two weight percent or less glycolide and approximately thirty-eight weight percent or more optically inactive dl-lactide having the unexpected characteristic of being crystalline. According to prior art teachings such compositions are characteristically amorphous. However, the compositions of the present invention have a bioabsorbable, segmented molecular architecture comprising a plurality of dl-lactide and glycolide linkages and mixtures thereof which are unexpectedly crystalline. The crystallinity of such compositions is unexpected since dl-lactide linkages are characteristically non-crystalline or amorphous.
• the process of manufacturing the compositions of the present invention is a two or more stage ring-opening copolymerization of highly reactive monomer linkages utilizing an initiator.
• a catalyst is also employed in the suitable methods used to produce the crystalline compositions described in detail below. It is important to note that the catalyst type and the level of catalyst employed affect both the polymerization and transesterification rates of the cyclic esters described in this invention. Tin based catalysts such as stannou ⁇ chloride dihydrate and stannous octoate are preferred. Additionally, the inherent viscosity or molecular weight of the subject composition is strongly influenced by the amount of initiator used during polymerization. Again, the methods of producing the novel compositions of the present invention are described in great detail below.
• compositions of the present invention are useful in the area of medical devices in that the compositions are readily bioabsorbable and have superior physical and tensile properties over amorphous copolymers of the same composition.
• Medical devices fabricated from the subject crystalline compositions are dimensionally stable at ambient conditions in contrast to amorphous counterparts.
• Other objects of the invention are achieved herein by providing absorbable medical devices derived from the novel crystalline compositions of the present invention.
• the novel unexpectedly crystalline compositions of the present invention are made up of approximately sixty-two weight percent or less glycolide and approximately thirty-eight weight percent or more optically inactive dl-lactide but preferably approximately fifty weight percent glycolide and approximately fifty weight percent optically inactive dl- lactide. According to prior art teachings and methods of manufacture such compositions were heretofore characteristically amorphous.
• the novel processes of manufacturing the novel crystalline compositions of the present invention are two or more stage ring-opening copolymerizations but preferably a two stage sequential addition copolymerization to increase crystallinity. The copolymerization is achieved by using one or more initiators and one or more catalysts.
• Suitable initiators for the manufacture of the crystalline copolymers of the present invention include but are not limited to alcohols.
• Suitable alcohol initiators include but are not limited to 1-docecanol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1, 10-decanediol, inositol, pentacrythritol, mannitol, sorbitol, erythritol, ethylene glycol and 1,3- propane diol.
• lauryl alcohol i.e., 1-docecanol is used as the initiator of choice to increase the polymer block characteristics, i.e., to increase sequence length and thereby increase the degree of crystallinity, of the copolymer .
• the inherent viscosity or molecular weight of a copolymer is directly influenced by the initiator and the amount of initiator used during the polymerization.
• an inherent viscosity of greater than 0.5 dl/g at a concentration of 0.5g/dl in a solvent such as hexafluoroisopropanol at 30°C is preferred.
• an inherent viscosity within the range of 0.3 to 0.8 dl/g but preferably 0.5 or 0.6 dl/g is preferred for controlled release devices where a strength value is not necessary.
• an inherent viscosity within the range of 0.05 to 0.3 dl/g but preferably .05 to 0.1 dl/g is required for adequate formability.
• a suitable inherent viscosity for fiber applications would be within the range of 0.8 dl/g or higher such as 2.0 dl/g but most preferably approximately l.Odl/g for adequate tensile properties.
• the initiator/dl-lactide ratio should be greater than approximately 1:60 but preferably approximately 1:100.
• a suitable melting point for the crystalline compositions of the present invention is at least 140°C but preferably 160°C or greater .
• the polymerization and transesterification rates of the cyclic esters of the present invention are directly influenced by the one or more catalysts employed.
• Suitable catalysts include but not limited to stannous chloride, dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin dichloride, stannic chloride pentahydrate, aluminum isopropoxide, antimony trioxide, stannic fluoride, stannous citrate, stannous acetate, antimony trifluoride, tin teteraisopropoxide, lead oxide, tetraisopropyl titanate, titanium acetyl acetonate, tetraoctylene glycol titanate, boron trifluoride etherate, aluminum trichloride, stannous chloride dihydrate and stannous octoate.
• Stannous chloride dihydrate and/or stannous actoate are preferred catalysts for the production of the present compositions due to their superior properties when utilized in a biological system. Most preferably stannous chloride dihydrate is used as the catalyst of choice in the present invention in order to control the required polymerization time. However, other catalysts would be suitable to produce the subject compositions although the tin based catalysts have been found to have superior bioabsorbable characteristics in vivo.
• Suitable reaction conditions for the present invention include polymerizations carried out at a temperature of approximately 160°C to 240°C but most preferably at a temperature of approximately 180°C to 200°C.
• the polymerizations are carried out within this temperature range over a period of approximately 1 hour to 4 hours but preferably approximately 2 to 3 hours to achieve the desired degree of crystallinity within the range of 2 to 30 percent, but preferably approximately 10 percent.
• the reaction conditions set forth herein likewise allows the subject compositions to be prepared in an economically and commercially desirable amount of time.
• a wide variety of absorbable, implantable medical devices can be manufactured in whole or in part from the novel copolymers of the present invention. Such devices include plugs, fasteners, pins, bone screws and other implantable devices.
• the novel copolymers of the present invention provide dimensional stability at ambient temperatures thereby eliminating the need for refrigerated shipping and storage of such medical implant devices. The elimination of the need for refrigeration makes the copolymers of the present invention economically and commercially desirable.
• the examples below are used to further describe and further illustrate a few of the novel crystalline copolymers of the present invention. The following examples are in no way intended to limit the scope of the novel crystalline compositions covered herein. Examples:
• Examples 1 through 6 50/50 to 75/25 Copolymers of dl- lactide/glycolide Six copolymers were prepared from glycolide and optically inactive dl-lactide. Ring opening polymerization of glycolide and dl-lactide were conducted using 0.40 mole percent with respect to the total monomer concentration of 1-dodecanol as the initiator and 0.001 to 0.005 mole percent with respect to total monomer concentration of stannous chloride dihydrate as catalyst. The polymerizations were carried out in a 2CV reactor. When combined, the molten mixture of monomers, initiator and catalyst was charged to a stirred reactor at 180°C, under nitrogen atmosphere, at 28 to 35 rpm.
• the reaction temperature was raised from 180°C to 200°C over a 15 minute time period. Stirring and heating was continued for an additional 45 minutes, for a total reaction time of two and one half hours. The reaction time was extended for some polymers.
• the resulting copolymers were ground and dried under vacuum at 110°C, 0.2 mm Hg, for 16 hours. Analytical results are summarized in Table 1. Molecular weight was characterized by a determination of the inherent viscosity in HFIP (Hexafluorisopropanol) at 30°C and a concentration of 0.5 g/dl as referenced in Table 1. Although all six copolymers were prepared by a single stage reaction, differences in their physical properties were influenced by composition.
• Examples 7 through 1 50/50 to 25/75 copolymers of dl- latide/glycolide
• Ring opening polymerization of dl-lactide and glycolide were conducted using 0.40 mole percent with respect to total monomer concentration of 1-dodencanol, i.e., lauryl alcohol as initiator and 0.005 mole percent with respect to total monomer concentration of stannous chloride dihydrate as catalyst.
• Copolymers were prepared by first synthesizing a prepolymer of glycolide and optically inactive dl-lactide with the desired monomer proportions, followed by a subsequent glycolide addition and continuation of the reaction for a specific length of time. The block length of the crystalizable linkages affecting the crystallinity of the final copolymer, was controlled through the glycolide proportions in the second stage.
• Polymerization was carried out in a 2 CV reactor.
• the molten mixture of monomers, initiator and catalyst was charged to the reactor at 180°C, under nitrogen atmosphere, and stirred at approximately 28 to 35 revolutions per minute (rpm) .
• the reaction temperature was raised from 180°C to 200°C over a 15 minute time period. Stirring and heating was continued for an additional 60 to 145 minutes, for a total reaction time of 2 to 2.5 hours.
• molten glycolide was added with continued stirring to provide a homogeneous distribution of the glycolide in the prepolymer.
• the reaction was allowed to continue for 15 to 45 minutes.
• the resulting polymers were ground and dried under vacuum for 19 hours at 110°C/0.2 Hg.
• compositions and polymer properties are listed in Table 2.
• the molecular weight was characterized by determination of inherent viscosity in HFIP (Hexaflurorisopropanol) at 30°C and a concentration of 0.5 g/dl .
• glycolide 97.53 g
• dl-lactide 151.35 g
• glycolide 97353 g
• dl-lactide 151.35 g
• glycolide 85.53 g
• dl-lactide 151.35 g
• glycolide 6.09 g
• dl-lactide 227.02 g
• glycolide 13.99 g
• dl-lactide 113.51 g
• Tg Polymer glass transition: midpoint of bwiition

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• Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Public Health (AREA)
• Organic Chemistry (AREA)
• Vascular Medicine (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Surgery (AREA)
• Veterinary Medicine (AREA)
• Polymers & Plastics (AREA)
• Medicinal Chemistry (AREA)
• Heart & Thoracic Surgery (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Polyesters Or Polycarbonates (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Materials For Medical Uses (AREA)
• Prostheses (AREA)

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• 1997
  • 1997-03-31 EP EP97917758A patent/EP0907338A4/en not_active Withdrawn
  • 1997-03-31 CA CA 2250760 patent/CA2250760A1/en not_active Abandoned
  • 1997-03-31 JP JP9535530A patent/JP2000508017A/ja active Pending
  • 1997-03-31 WO PCT/US1997/005294 patent/WO1997036553A1/en not_active Application Discontinuation
  • 1997-03-31 BR BR9710651A patent/BR9710651A/pt not_active Application Discontinuation
  • 1997-03-31 AU AU26004/97A patent/AU2600497A/en not_active Abandoned

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