Drug – bio-affecting and body treating compositions – Solid synthetic organic polymer as designated organic active... – Monomer contains oxygen
Patent
1993-05-05
1996-07-09
Azpuru, Carlos
Drug, bio-affecting and body treating compositions
Solid synthetic organic polymer as designated organic active...
Monomer contains oxygen
525 64, 528272, 528302, 528307, 528308, A61K 31765, C08G 6302, C08G 6316, C08G 6348
Patent
active
055342507
DESCRIPTION:
BRIEF SUMMARY
This invention concerns polymers containing optionally substituted methylene diester groupings. Such groupings are capable of being biodegradable since they are labile to common esterase enzymes although in many instances the polymer may remain at least partly intact.
Biodegradable polymers have long been used in the medical field, for example to provide biodegradable implant materials and delayed release drug delivery systems. They are now of wider interest in overcoming the problem of pollution by long-lived insert packaging materials, household articles, detergents and the like.
There is also a need for polymers which, when they wholly or partially break down by chemical or biological means, give reliably non-toxic products.
In general, biodegradation commonly involves enzymic hydrolysis of particular chemical bonds in the polymer, notably ester, urethane or amide groups which are otherwise stable in the absence of enzymes. Thus, for packaging materials, aliphatic polyesters such as polycaprolactone, polyethylene adipate and polyglycolic acid are candidate materials although polyethylene terephthalate, which is very widely used in textiles and fibres, is resistant to biodegradation.
In the medical field, resorbable polymers are of interest for sutures and in wound closure, resorbable implants in the treatment of osteomyelitis and other bone lesions, tissue stapling and mesh tamponades, anastomosis as well as drug delivery systems and diagnostics. In these fields, polylactic acid, polyglycolic acid, poly (L-lactide-co-glycolide), polydioxanone, poly (glycolide-co-trimethylene carbonate), poly (ethylene carbonate), poly (iminocarbonates), polyhydroxybutyrate, poly (amino acids), poly (ester-amides), poly (orthoesters) and poly (anhydrides) have all been proposed (T. H. Barrows, Clinical Materials 1 (1986), pp. 233-257) as well as natural products such as polysaccharides. U.S. Pat. No. 4,180,646, in particular, describes novel poly (orthoesters) for use in a very wide range of products.
However, the polymers hitherto proposed for either medical or more general use have each had one or more disadvantages and there is a demand for alternative polymers, in particular polymers containing readily biodegradable groupings. The present invention is based in the concept that diester units of the formula (I) degraded by common esterase enzymes but are stable in the absence of enzymes.
A number of polymers containing such units have been described in the prior art. Thus, for example, U.S. Pat. No. 2,341,334 describes the copolymerisation of monomers such as methylidene or ethylidene dimethacrylate with ethylenic monomers such as vinyl acetate, methyl methacrylate or styrene. The resulting copolymers are said to exhibit higher softening points than unmodified homopolymers of the ethylenic monomer and to be useful in the preparation of cast articles. DD-A-95108 and DE-A-1104700 similarly describe the copolymerisation of various alkylidene diacrylate esters with acrylic monomers to yield copolymers with modified physical properties. A number of alkylidene dicrotonates are disclosed in U.S. Pat. No. 2,839,572 as monomers which may be homopolymerised or copolymerised with materials such as vinyl chloride, to yield resins useful as protective coatings. Kimura H. in J. Osaka Univ. Dent. Sch., 20 (1980), pp. 43-49 describes the use of propylidyne trimethacrylate as a crosslinking agent in coating dental polymethylmethacrylate in order to improve its abrasion resistance. Homopolymers of ethylidene, allylidene and benzylidene dimethacrylate are described in FR-A-2119697 and by Arbuzova A. et al. in Zh. Obshch. Khim. 26 (1956), pp. 1275-1277, and typically comprise hard, glassy materials.
EP-A-0052946 discloses the use of certain polyacrylates to stabilise polyhydroxybutyric acid. The only polyacrylate having more than one acryloyloxy group attached to a single carbon atom is pentaerithrityl monohydroxypentaacrylate, which by virtue of its numerous ethylenically unsaturated sites would be expected to form a complex mixture of a
REFERENCES:
patent: 2341334 (1944-02-01), Richter
patent: 2839572 (1958-06-01), Guest et al.
Klaveness Jo
Strande Per
Wiggen Unni N.
Azpuru Carlos
Nycomed Imaging AS
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