Drug – bio-affecting and body treating compositions – Designated organic nonactive ingredient containing other... – Aftertreated solid synthetic organic polymer
Reexamination Certificate
1998-01-13
2001-04-03
Webman, Edward J. (Department: 1617)
Drug, bio-affecting and body treating compositions
Designated organic nonactive ingredient containing other...
Aftertreated solid synthetic organic polymer
C525S424000, C525S430000, C525S449000, C525S454000, C525S408000
Reexamination Certificate
active
06211249
ABSTRACT:
The present invention relates to novel bioabsorbable polymeric compositions based upon AB polyester polyether or related diblocks. Compositions according to the present invention may be used in medical applications, for example, for reducing or preventing adhesion formation subsequent to medical procedures such as surgery, for producing surgical articles including stents and grafts, as coatings, sealants, lubricants, as transient barriers in the body, for materials which control the release of bioactive agents in the body, for wound and burn dressings and producing biodegradable articles, among numerous others.
BACKGROUND OF THE INVENTION
The desire to find improved polymeric compositions which can be used for specific medical and environmental applications is ever present. There is a continuous search for new, improved biodegradable polymers to provide enhanced materials which are biocompatible, have good bioabsorbtive/biodegrable properties, appropriate mechanical and physical properties and related structural characteristics which find use in the prescribed application. Materials which provide superior characteristics as well as flexibility in formulation and manufacture are especially desirable.
Early biodegradable/bioabsorbable polymers focused on polylactic and/or polyglycolic acid homopolymers or copolymers which were used primarily in bioabsorbable sutures. These early polymers suffered from the disadvantage that the polymers tended to be hard or stiff and often brittle with little flexibility. In addition, the kinetics of their degradation tended to be slow in certain applications, necessitating research on polymers with faster degradation profiles.
A number of other copolymers utilizing lactic acid, glycolic acid, &egr;-caprolactone, poly(orthoesters) and poly(orthocarbonates), poly(esteramides) and related polymers have been synthesized and utilized in medical applications with some measure of success. The polymers tend to be limited, however, by disadvantages which appear in one or more of the following characteristics: flexibility, strength, extensibility, hardness/softness, biocompatability, biodegradability, sterilizability, ease of formulation over a wide range of applications and tissue reactivity.
Recent investigative attention has centered on the production of ACA triblock polymeric compositions which are derived from blocks of poly(oxy)alkylene and polyhydroxycarboxylic acids. These formulations, among others have exhibited favorable characteristics for use to reduce and/or prevent adhesion formulation secondary to surgery and other medical applications.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide novel polymeric materials which may be used in a variety of medical, environmental and other applications where biodegradability/bioerodability is an important feature of the application.
It is an additional object of the invention to provide polymeric materials which may be manufactured in film form and other solid structures such as rods, cylinders, porous structures such as foams, dispersions, viscous solutions, liquid polymers, pastes, sprays or gels which may be administered easily or adapted for use in a wide range of applications.
It is yet another object of the invention to provide polymeric materials which may be used to substantially prevent adhesions and which may be effective for delivering bioactive agents.
It is yet an additional object of the invention to provide bioabsorbable polymeric materials which can be produced in a variety of formulations which have acceptable strength, may be reactive or non-reactive with patient tissue depending upon the desired application and are bioabsorbable.
It is yet another object of the present invention to provide polymeric barriers which can be used in various forms, e.g., films, other structures such as rods and cylinders, foams, gels, dispersions, liquid polymers, pastes, sprays or viscous solutions, to provide flexibility in administration and use in a variety of applications, including medical applications, environmental applications and other applications.
These and/or other objects of the invention may be readily gleaned from the detailed description of the present invention which follows.
SUMMARY OF THE INVENTION
The present invention relates to multiblock polymeric materials which utilize AB diblocks as building blocks for the polymeric materials.
The present invention preferably relates to polymeric compositions comprising coupled or crosslinked poly(ester)/polyether AB or related AB diblocks, where A is a polyester unit derived from the polymerization of monomers and B is a monofinctional hydroxyl, amine or carboxyl containing molecule (which may be monomeric or polymeric) which is end-capped with a non-reactive group, such that the hydroxyl, amine or carboxyl-containing molecule initiates the polymerization of the monomers to form the polyester unit (A block). In preferred embodiments according to the present invention, the polyester unit A is derived from the polymerization of monomers selected from the group consisting of lactic acid, lactide, glycolic acid, glycolide, &bgr;-propiolactone, &egr;-caprolactone, &dgr;-glutarolactone, &dgr;-valerolactone, &bgr;-butyrolactone, pivalolactone, &agr;,&agr;-diethylpropiolactone, ethylene carbonate, trimethylene carbonate, &ggr;-butyrolactone, p-dioxanone, 1,4-dioxepan-2-one, 3-methyl-1,4-dioxane-2,5-dione, 3,3,-dimethyl-1-4-dioxane-2,5-dione, cyclic esters of &agr;-hydroxybutyric acid, &agr;-hydroxyvaleric acid, &agr;-hydroxyisovaleric acid, &agr;-hydroxycaproic acid, &agr;-hydroxy-&agr;-ethylbutyric acid, &agr;-hydroxyisocaproic acid, &agr;-hydroxy-&agr;-methyl valeric acid, &agr;-hydroxyheptanoic acid, &agr;-hydroxystearic acid, &agr;-hydroxylignoceric acid, salicylic acid and mixtures, thereof. B may be derived from any monofunctional hydroxyl, amine or carboxyl containing molecule which is capable of initiating polymerization of the monomers which comprise the A block. In preferred aspects of the present invention, the monofunctional molecule (which is also referred to as a “monofinctional initiator molecule”) is a C
1
to C
12
amine, alcohol or carboxylic acid. The alcohol, amine or carboxylic acid may be an alkyl amine, alcohol or carboxylic acid, an aryl amine, alcohol or carboxylic acid, an aralkyl amine, alcohol or carboxylic acid or a substituted alkyl arnine, alcohol or carboxylic acid, substituted aryl amine, alcohol or carboxylic acid or a substituted aralkyl amine, alcohol or carboxylic acid. In alternative embodiments, the monofunctional initiator molecule is a poly(oxyalkylene) molecule or a poly(oxyalkylene)-containing molecule, preferably poly (ethylene glycol), varying in molecular weight from as low as 100 (diethylene glycol) to hundreds of thousands or more, with a preferred molecular weight ranging from about 550 to about 5,000 or more.
The AB diblocks described above may be utilized without further modification, or preferably, they may be coupled with a chain-extender or coupling agent as described in more detail herein to produce coupled diblocks or multiblocks according to the present invention. Polymeric compositions according to the present invention are advantageously end-capped with inert groups, i.e. they preferably do not contain any reactive groups at their ends which will participate in any reaction. By relying on end-capping with inert groups, the present compositions unexpectedly attain a storage stability, whether in solid form or solution, which is significantly enhanced compared to compositions which are end-capped with reactive groups such as hydroxyl, amine or carboxylic acid groups.
The present invention relates to a polymer of the chemical structure:
where a is a positive integer,
X is a C
1
-C
8
alkylene group, preferably a C
1
(CH) alkylene group,
R
1
is H or CH
3
, preferably H when X is a C
2
-C
8
alkylene group and Z is derived from an amine- or hydroxyl-containing monofunctional monomeric or polymeric compound end-capped with an amine or hydroxyl group, the amine- or alcoh
Cohn Daniel
Levi Avraham
Stern Theodor
Coleman Henry D.
Life Medical Sciences, Inc.
Sudol R. Neil
Webman Edward J.
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