Claims
- 1. A controlled release matrix dosage form comprising 1% to 75% by weight of a pharmaceutically active ingredient; 5% to 50% of a polymer of lactic acid; and 1% to 90% of an excipient selected from the group consisting of lactose, dicalcium phosphate, calcium sulfate, sugars, microcrystalline cellulose, gums, methylcellulose, starch, polyvinylpyrrolidone and clay; the polymer of lactic acid having a weight average molecular weight of about 2500 to about 4500 and containing less than about 4% lactide; and made by the steps of:
- (a) heating lactic acid in a inert atmosphere to about 110.degree. C. at approximately 101 kPa,
- (b) advancing the temperature to about 120.degree. C.,
- (c) maintaining the temperature between about 120.degree. and 140.degree. at a pressure of about 80 kPa a sufficient time to remove about 52% of the theoretical amount of water, and subsequently advancing the temperature to 180.degree. C. to 190.degree. C. while reducing the pressure to about 10 kPa,
- (d) maintaining the temperature and pressure at about 190.degree. C. and 10 kPa for a time sufficient to remove about 92% of the residual water, and
- (e) reducing the pressure to about 400 Pa while maintaining the temperature at least about 180.degree. C. for a time sufficient to remove about 98% of the theoretical water and about 0.5% of the lactic acid as lactide to provide the poly(lactic acid) containing less than about 4% lactide.
- 2. A controlled release matrix dosage form of claim 1 wherein the excipient is selected from the group consisting of lactose, dicalcium phosphate, calcium sulfate, sugars, microcrystalline cellulose, gums, methylcellulose, starch, polyvinylpyrrolidone and clay.
- 3. The controlled release dosage form of claim 1 wherein the pharmaceutically active ingredient is selected from the group consisting of theophylline, quinidine sulfate, propanolol, chloropheniramine, testosterone and ethenyl estradiol.
Parent Case Info
This is a continuation of U.S. patent application Ser. No. 503,397 filed Apr. 2, 1990, now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4728721 |
Yamamoto et al. |
Mar 1988 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
60-181029A |
Sep 1985 |
JPX |
Non-Patent Literature Citations (1)
Entry |
Mark et al., Collected Papers of Wallace Hume Carothers on High Polymeric Substances, Interscience Publishers, Inc. (1940), pp. 152-153. |
Continuations (1)
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Number |
Date |
Country |
Parent |
503397 |
Apr 1990 |
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