Drug – bio-affecting and body treating compositions – Solid synthetic organic polymer as designated organic active...
Reexamination Certificate
1999-06-30
2002-12-24
Mullis, Jeffrey (Department: 1711)
Drug, bio-affecting and body treating compositions
Solid synthetic organic polymer as designated organic active...
C424S078260, C424S078270, C424S078310, C424S078350, C424S078370, C525S063000, C525S066000, C525S293000, C525S296000
Reexamination Certificate
active
06497868
ABSTRACT:
TECHNICAL FIELD
The present invention relates to graft polymer which can be applied to a polymer base material, and to moulded medical articles employing this graft polymer.
TECHNICAL BACKGROUND
In the medical treatment field, infections which occur during the insertion/retention in the patient's body of a medical device comprising a polymer material such as polyurethane constitute a complication and are regarded as a problem. Hitherto, in order to prevent infections accompanying the retention of a medical device, the medical device has either been disinfected just prior to use by immersion, or the like, in an aqueous solution containing an antimicrobial agent or disinfectant such as chlorhexidine or povidone-iodine, or frequent replacement has been carried out in the case of a medical device which can be replaced during treatment. However, because antimicrobial agents and disinfectants disappear from a medical devices surface with time, the disinfection effect does not persist and it is found that when a medical device is used over a long time, this effect gradually declines. Moreover, the frequent replacement of medical devices is a considerable burden to medical workers. Hence, as a further means for preventing infections, medical devices have been subjected to various antimicrobial treatments. Typical thereof are catheters coated on their surface with a layer containing an antimicrobial agent such as dhlorhexidine, or a. metal such as silver or copper or compound thereof. In the case of these catheters, a system is employed for slow release into the body of uniform quantities of the material with an antimicrobial action, and they show a good effect compared to the case where the catheter is disinfected just prior to use.
However, with a system of slow release of an antimicrobial agent, the period of use still has limits and a gradual decline in efficacy is unavoidable. Moreover, the metabolism following slow release of a metal such as silver or compound thereof is unclear, and injury to the body is conceivable. Again, where silver remains in the discarded medical device following use, recovery thereof or other special treatment is required at the time of disposal.
Hence, polymers with quaternary ammonium groups have been variously proposed as polymers which are not of the slow-release type but which have inherent antimicrobial character (Japanese Examined Patent Publication Nos 54-17797 and 54-18817). However, the processability of these polymers is poor, and they cannot alone be formed into moulded articles, so it is necessary either to coat them onto the surface of a moulded polymer which has excellent mechanical characteristics, or to carry out blending and moulding along with such a polymer. However, the better the mechanical characteristics of the base material polymer, the worse its compatibility with other polymers and, where compatibility is poor, a coated polymer peels away or cracks are produced. Now, there has been described in Japanese Unexamined Patent (Kokai) Publication No. 6-337378 a hydrogel containing a copolymer of hydroxypolyalkyleneglycol (meth)acrylate and monomer with a quaternary ammonium salt in a side chain, and again in Japanese Unexamined Patent Publication No. 6-256424 there is described a hydrogel containing a copolymer of a monomer possessing hydroxypolyalkyleneglycol, a monomer possessing a quaternary ammonium salt in a side chain and vinyl monomer. However, in neither case are graft copolymers described and, with these polymers, there are limits to the selective manifestation of the properties of the trunk and graft components. In other words, at present, no antimicrobial polymers are known with satisfactory compatibility to the base material polymer.
The present inventors have considered the problems of the prior-art and, as a result of extensive investigation to obtain an antimicrobial polymer which forms flexible films, such that it can be applied to medical devices of complex shape, and which also has good compatibility and adhesion to various polymers, they have discovered that polymer comprising moieties containing general formula (I) graft polymerized to polymer containing vinyl chloride has good compatibility and adhesion to various polymers and also has a strong antimicrobial action. It is on this discovery that the present invention is based. Thus, the present invention has the objective of offering polymer which can form flexible films and can be suitably applied to base materials of complex shapes; together with moulded medical articles employing this polymer.
DISCLOSURE OF THE INVENTION
The present invention relates to graft polymer which is formed by graft polymerization of structural units containing a quaternary ammonium group represented by general formula (A)
(R
2
and R
3
each represent an alkyl group with from 1 to 3 carbons, and R
4
represents an alkyl group with from 3 to 18 carbons. X represents at least one type of ion selected from halogen, sulphate, hydroxide and carboxylic acid ions.),
preferably to graft polymer where the structural units containing a quaternary ammonium group represented by general formula (A) are structural units represented by general formula (I),
(R
1
represents at least one species selected from hydrogen, the methyl group and the ethyl group, and n represents an integer in the range 1 to 12. A represents at least one species selected. from O, S and NR
5
. R
5
represents hydrogen or an alkyl group with from 1 to 12 carbons.), or
to graft polymer formed by the graft polymerization of structural units containing a quaternary ammonium group and structural units containing an alkoxypolyalkylene glycol moiety represented by the general formula (B),
—(R
5
O)
n
R
6
(B)
(n represents an integer in the range 1 to 100. R
5
represents a straight-chain or branched alkylene group with from 1 to 4 carbons, and R
6
represents at least one species selected from hydrogen and straight-chain or branched alkyl groups with from 1 to 4 carbons.).
Furthermore, the present invention relates to moulded medical articles formed by coating aforesaid graft polymer onto a moulded medical article used for insertion into the body, or by blending the graft polymer therewith.
OPTIMUM MODE FOR PRACTISING THE INVENTION
Next, the present invention is explained in further detail.
The graft polymer in the present invention has functional groups represented by formula (A), as stated above. As examples of the structural units with a functional group represented by formula (A), there are structural units wherein formula (A) is bonded to the main chain via an ester linkage, amide linkage, ureido linkage, ether linkage, alkylene group or phenylene group. Of these, from the point of view of ready availability of the precursor, it is preferred that the structural units with a functional group represented by formula (A) are structural units represented by the following formula (I).
(R
1
represents at least one species selected from hydrogen, the methyl group and the ethyl group, R
2
and R
3
each represent an alkyl group with from 1 to 3 carbons, and R
4
represents an alkyl group with from 3 to 18 carbons. n represents an integer in the range 1 to 12. A represents at least one species selected from O, S and NR
5
. R
5
represents hydrogen or an alkyl group with 1 to 12 carbons. X represents at least one ion selected from halogen, sulphate, hydroxide and carboxylic acid ions.)
n represents an integer in the range 1 to 12, but it contributes to the degree of freedom of the antimicrobial functional group and if it is too short then the functional group does not move freely so, for example, it does not readily come into contact with bacteria, while if it is too long then the hydrophobic character is strengthened so that in an aqueous medium containing bacteria the antimicrobial functional group does not readily come into contact with the bacteria.
R
2
and R
3
are alkyl groups. As the number of carbons is increased, they become more strongly hydrophobic so contact between the antimicrobial functional group and b
Mullis Jeffrey
Toray Industries Inc.
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