Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1997-11-26
2001-03-27
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S411000, C525S413000, C528S068000, C528S073000, C528S081000, C523S116000, C523S118000, C523S122000, C427S002310, C424S426000
Reexamination Certificate
active
06207767
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This disclosure relates generally to bioabsorbable polymer compositions. Specifically, this disclosure relates to highly branched or star polymers derived from monomers known to form absorbable polymers. The bioabsorbable polymer compositions are particularly useful in the manufacture of absorbable surgical devices such as sutures, staples clips, anastomosis rings, bone plates and screws, matrices for the sustained and/or controlled release of pharmaceutically active ingredients, etc., fabricated at least in part therefrom.
2. Background of Related Art
Polymers and copolymers of, and surgical devices made from, lactide and/or glycolide and/or related compounds are well-known. See, e.g., U.S. Pat. Nos. 2,668,162, 2,683,136, 2,703,316, 2,758,987, 3,225,766, 3,268,486, 3,268,477, 3,297,033, 3,422,181, 3,442,871, 3,463,158, 3,468,853, 3,531,561, 3,565,869, 3,597,449, 3,620,218, 3,626,948, 3,636,956, 3,736,646, 3,739,773, 3,772,420, 3,773,919, 3,781,349, 3,784,585, 3,792,010, 3,797,499, 3,839,297, 3,846,382, 3,867,190, 3,875,937, 3,878,284, 3,896,802, 3,902,497, 3,937,223, 3,982,543, 4,033,938, 4,045,418, 4,057,537, 4,060,089, 4,137,921, 4,157,437, 4,243,775, 4,246,904, 4,273,920, 4,275,813, 4,279,249, 4,300,565, and 4,744,365, U.K. Pat. or Appln. Nos. 779,291, 1,332,505, 1,414,600, and 2,102,827, D. K. Gilding et al., “Biodegradable polymers for use in surgery-polyglycolic/poly (lactic acid) homo- and copolymers: 1,
“Polymer,
Volume 20, pages 1459-1464 (1979), and D. F. Williams (ed.),
Biocompatibility of Clinical Implant Materials,
Volume II, chapter 9: “Biodegradable Polymers” (1981).
In addition, other patents disclose surgical devices prepared from copolymers of lactide or glycolide and other monomers including caprolactone or trimethylene carbonate have been prepared. For example, U.S. Pat. No. 4,605,730 and U.S. Pat. No. 4,700,704 disclose copolymers of epsilon-caprolactone and glycolide useful in making surgical articles and particularly surgical sutures having low Young's modulus. In addition, U.S. Pat. No. 4,624,256 relates to the utilization of high molecular weight caprolactone polymers as coating for surgical sutures, while U.S. Pat. No. 4,429,090, discloses surgical articles manufactured from triblock copolymers prepared from copolymerizing glycolide with trimethylene carbonate.
Polymers, copolymers and surgical devices made from epsilon-caprolactone and/or related compounds have also been described in U.S. Pat. Nos. 3,169,945, 3,912,692, 3,942,532, 4,605,730, 4,624,256, 4,643,734, 4,700,704, 4,788,979, 4,791,929, 4,994,074, 5,076,807, 5,080,665, 5,085,629 and 5,100,433.
Polymers derived in whole or in part from dioxanone are known. Homopolymers of p-dioxanone are described, e.g., in U.S. Pat. Nos. 3,063,967; 3,063,968; 3,391,126; 3,645,941; 4,052,988; 4,440,789; and, 4,591,630. Copolymers containing units derived from p-dioxanone and one or more other monomers that are copolymerizable therewith are described, e.g., in U.S. Pat. Nos. 4,243,775; 4,300,565; 4,559,945; 4,591,630; 4,643,191; 4,549,921; 4,653,497; 4,791,929; 4,838,267; 5,007,923; 5,047,048; 4,076,807; 5,080,665; and 5,100,433 and European Patent Application Nos. 501,844 and 460,428. Most of the known dioxanone-derived homopolymers and copolymers are indicated to be useful for the fabrication of medical and surgical devices such as those previously mentioned.
The properties of the bioabsorbable polymers may differ considerably depending on the nature and amounts of the comonomers, if any, employed and/or the polymerization procedures used in preparing the polymers. Aforementioned U.S. Pat. No. 4,838,267 discloses block copolymers derived from p-dioxanone and glycolide that exhibit a high order of initial strength and compliance but lose their strength rapidly after implantation in the body. Sutures made from the copolymers are said to be particularly useful in surgical procedures, such as plastic surgery or repair of facial wounds, where it is desirable for the suture to lose its strength rapidly.
SUMMARY
The general formula of the novel polymers described herein is:
CH
2
OR
1
—(CHOR
2
)—(CHOR
3
)—(CHOR
4
) . . . (CHOR
n
)—CH
2
OR
n+1
wherein: n equals 1 to 13, preferably 2 to 8 and most preferably 2 to 6;
R
1
, R
2
. . . R
n+1
are the same or different and selected from the group of a hydrogen atoms or (Z)
m
wherein Z comprises repeating units selected from the group consisting of:
wherein p is 3 to 8 and each R′ may be the same or different and are individually selected from the group consisting of hydrogen and alkyl having from 1 to 5 carbon atoms, such that at least three of said R
1
, R
2
. . . R
n+1
groups are other than hydrogen;
m is sufficient such that the star polymer has an inherent viscosity in HFPI at 25° C. between about 0.05 and about 0.5 dl/gm, preferably from about 0.15 to about 0.3 dl/gm, and most preferably from about 0.15 to about 0.2 dl/gm; and
the m's for each (Z) group may be the same or different.
The polymers are initiated with a polyhydric alcohol. Preferred initiators are mannitol, pentaerythritol and threitol.
In a particularly useful embodiment, a bioabsorbable polymer of the foregoing general formula is provided wherein (Z) consists essentially of repeating units of the formula:
and the polymer has an inherent viscosity between about 0.05 and 0.5 dl/gram in HFIP at 25° C.
The polymers described herein are useful in the production of surgical devices. In particularly useful embodiment the polymers are used in coatings on surgical devices, such as, for example fibers used to produce sutures, meshes, woven structures, etc.
The polymers may be endcapped with an isocyanate. The isocyanate capped polymer may be cross-linked in the presence of water and/or a catalyst, such as tertiary amine catalyst. The cross-linked star polymers are useful for example as bone adhesives or bone fillers. Optionally, the polymer may be mixed with a filler such as hydroxyapatite or other bioceramic prior to cross-linking to produce a bone putty.
Alternatively, after endcapping with an isocyanate, a charge may be chemically induced on the polymer, such as, for example by reacting a fraction of the available isocyanate groups with diethylene ethanolamine (DEAE) and then cross-linking at least a portion of the balance of the remaining available isocyanate groups to form a water-insoluble, degradable, charged particle. These charged compositions are useful for example as an agent to enhance soft tissue would healing.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The general formula of the basic polymer in accordance with this disclosure is:
CH
2
OR
1
—(CHOR
2
)—(CHOR
3
)—(CHOR
4
) . . . (CHOR
n
)(—CH
2
OR
n+1
wherein: n equal 1 to 13, preferably 2 to 8 and most preferably 2 to 6;
R
1
, R
2
. . . R
n+1
are the same or different and selected from the group of a hydrogen atom or (Z)
m
wherein Z comprises repeating units selected from the group consisting of:
wherein p is 3 to 8 and each R′ may be the same or different and are individually selected from the group consisting of hydrogen and alkyl having from 1 to 5 carbon atoms, such that at least three of said R
1
, R
2
. . . R
n+1
groups are other than hydrogen;
m is sufficient such that the star polymer has an inherent viscosity in HFIP at 25° C. between about 0.05 and about 0.5 dl/gm, preferably from about 0.15 to about 0.3 dl/gm; and most preferably from about 0.15 to about 0.2 dl/gm, and
the m's for each Z group may be the same or different.
The purified monomer(s) used to form the Z groups are preferably dried and then polymerized at temperatures ranging from about 20° C. to about 130° C., preferably above 75° C., in the presence of an organometallic catalyst such as stannous octoate, stannous chloride, diethyl zinc or zirconium acetylacetonate. The polymerization time may range from 1 to 100 hours or longer depending on the other polymerization parameters but generally polymerization times of about 12 to about 48 hours are employed
Bennett Steven L.
Connolly Kevin M.
Gruskin Elliott A.
Jiang Ying
Buttner David J.
United States Surgical Corporation
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