Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2001-09-05
2004-06-08
Hightower, P. Hampton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S355000, C528S359000, C525S411000, C525S413000, C525S415000, C606S065000, C606S075000, C606S075000, C606S077000, C606S151000, C606S219000, C606S224000, C606S228000, C606S230000, C606S231000, C606S232000, C606S233000, C623S001110, C623S001150, C623S001380, C623S001420
Reexamination Certificate
active
06747121
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to implantable, resorbable copolymers containing L-lactide and glycolide repeat units, and in particular to terpolymers containing L-lactide, glycolide, and one other type of repeat unit selected from the group consisting of D-lactide, D,L-lactide, and &egr;-caprolactone. Medical devices for in vivo implantation applications containing such implantable, resorbable copolymers are also described, as well as methods for making such copolymers and devices.
BACKGROUND OF THE INVENTION
There is a wealth of information regarding the utility of polylactides, polyglycolides, and other resorbable materials, particularly pertaining to resorbable implants. These resorbable implants, as compared to traditional, non-resorbable metal or composite implants, for example, have the advantage of being biocompatible, of being biodegradable after a period of time, and of not requiring removal, e.g., in bone fixation or repair applications.
Copolymers containing resorbable materials can be made as well. Certain varieties of these copolymers have been made and described in the following publications.
U.S. Pat. Nos. 5,223,546 and 5,238,968 describe polymer networks based on a foam formed from the combination of a foaming agent, a poly(lactic acid)-base resin, and an optional plasticizer. The poly(lactic acid)-base resin may comprise a polymer made of lactic acid or a lactic acid-hydroxycarboxylic acid copolymer.
U.S. Pat. No. 5,236,431 describes a resorbable fixation device useful for treating torn bodily material in vivo. This fixation device, according to the disclosure, can contain resorbable copolymers made from a variety of possible monomers, including highly purified polyhydroxyacids such as lactides and gylcolide.
U.S. Pat. No. 5,322,925 describes surgical articles made from absorbable polymers. The absorbable polymers of this disclosure are block copolymers of one type or another, containing various combinations of lactide, glycolide, and/or trimethylene carbonate in the block segments.
U.S. Pat. No. 5,599,852 discloses injectable, bioabsorbable microdispersions including liquid polymers for tissue augmentation and repair. The liquid polymers of this disclosure contain a first set of repeating units from lactones including caprolactone, trimethylene carbonate, ether lactones, or combinations thereof, and a second set of repeating units including lactides, glycolides, p-dioxanone, or combinations thereof.
SUMMARY OF THE INVENTION
The invention primarily relates to terpolymers having repeat units of L-lactide, glycolide, and either D,L-lactide, D-lactide, or &egr;-caprolactone, as well as implantable and/or resorbable medical devices containing such terpolymers. The implantable and/or resorbable medical devices containing such terpolymers may advantageously be fabricated into the form of a bone fixation plate, screw, tack, clip, staple, pin, rod, anchor, scaffold, sponge, implant for cell encapsulation, implant for tissue engineering, drug delivery device, monofilament or multifilament structure, sheet, membrane, and a foamed article.
In one embodiment, the terpolymer contains from about 75% to about 90% L-lactide repeat units, from about 4% to about 11% D-lactide repeat units, and from about 4% to about 18% glycolide repeat units. In a preferred embodiment, the terpolymer consists essentially of about 90% L-lactide repeat units, about 5% D-lactide repeat units, and about 5% glycolide repeat units. In another preferred embodiment, the terpolymer consists essentially of about 85% L-lactide repeat units, about 5% D-lactide repeat units, and about 10% glycolide repeat units.
In another embodiment, the terpolymer contains at least about 50% L-lactide repeat units, from about 1% to about 20% repeat units from &egr;-caprolactone, and from about 1% to about 30% glycolide repeat units. In a preferred embodiment, the terpolymer consists essentially of about 80% L-lactide repeat units, about 10% repeat units from &egr;-caprolactone, and about 10% glycolide repeat units.
In still another embodiment, the terpolymer contains at least about 50% L-lactide repeat units, from about 1% to about 20% D,L-lactide repeat units, and from about 1% to about 30% glycolide repeat units. In a preferred embodiment, the terpolymer consists essentially of about 80% L-lactide repeat units, about 10% D,L-lactide repeat units, and about 10% glycolide repeat units. In another preferred embodiment, the terpolymer consists essentially of about 80% L-lactide repeat units, about 5% D,L-lactide repeat units, and about 15% glycolide repeat units.
In yet another embodiment, from about 1% to about 20% of the repeat units of the terpolymer are D-lactide repeat units; preferably, from about 4% to about 11% of the repeat units of the terpolymer are D-lactide repeat units. In another embodiment, from about 50% to about 95% of the repeat units of the terpolymer are L-lactide repeat units; preferably, from about 75% to about 90% of the repeat units of the terpolymer are L-lactide repeat units. In another embodiment, from about 1% to about 30% of the repeat units of the terpolymer are glycolide repeat units; preferably, from about 4% to about 18% of the repeat units of the terpolymer are glycolide repeat units.
The terpolymer may also be expressed as having repeat units depicted by the following formula:
wherein the repeat unit having subscript x is an L-lactide repeat unit, the third component having subscript y is either a D-lactide repeat unit, a D,L-lactide repeat unit, or a repeat unit based on a ring-opened &egr;-caprolactone structure. Advantageously, the molar percentages of the repeating units are such that x is from about 0.75 to about 0.9, y is from about 0.02 to about 0.16, z is from about 0.04 to about 0.18, and x+y+z=1.
In one embodiment, x is from about 0.75 to about 0.9, y is from about 0.04 to about 0.11, and z is from about 0.05 to about 0.15. In a preferred embodiment, x is essentially about 0.85, y is essentially about 0.05, and z is essentially about 0.1. In another preferred embodiment, x is essentially about 0.9, y is essentially about 0.05, and z is essentially about 0.05.
Another aspect of the invention relates to implantable medical devices that contain any of the terpolymers listed above.
In one embodiment, the terpolymers can be made by a process that includes combining L-lactic acid monomer, from about 2% to about 16% of D-lactic acid monomer, and glycolic acid monomer to form a monomer mixture and polymerizing substantially all of the monomer mixture to form the terpolymer.
In another embodiment, the terpolymer can be made by a process that includes combining L-lactide dimer, D-lactide dimer, and glycolide dimer to form a dimer mixture and polymerizing substantially all of the dimer mixture to form the terpolymer.
In yet another embodiment, the terpolymer can be made by a process that includes contacting a combination of monomers and dimers that correspond to repeat unit structures of L-lactide, D-lactide, and glycolide to form a monomer-dimer mixture and polymerizing substantially all of the monomer-dimer mixture to form the terpolymer.
In still another embodiment, the terpolymer can be made by a process that includes combining L-lactide dimer, D,L-lactide dimer, and glycolide dimer to form a dimer mixture and polymerizing substantially all of the dimer mixture to form the terpolymer.
In another embodiment, the terpolymer can be made by a process that includes contacting a combination of monomers and dimers that correspond to repeat unit structures of L-lactide, D,L-lactide, and glycolide to form a monomer-dimer mixture and polymerizing substantially all of the monomer-dimer mixture to form the terpolymer.
In another embodiment, the terpolymer can be made by a process that includes combining L-lactic acid monomer, &egr;-caprolactone monomer, and glycolic acid monomer to form a monomer mixture and polymerizing substantially all of the monomer mixture to form the terpolymer.
In another embodiment, the terpolymer can be made by a proce
Day Jones
Hampton Hightower P.
Synthes (USA)
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