Abstract

The objective of the present study is to formulate and evaluate theophylline polymeric matrix tablets for controlled release using sintering technique. The powder of ethylene vinyl acetate copolymer 1802 was prepared by a novel spray technique. The micromeritics of the powdered vinyl acetate copolymer were studied. Matrix tablets of theophylline in vinyl acetate copolymer were prepared in different drug and polymer ratios using direct compression and subsequent sintering technique at various temperatures. The sintered tablets were evaluated for various tablet characteristics including dissolution rate. A comparative dissolution rate study was conducted with the optimized formula against three commercial theophylline sustained release products. A simple process for powdering of vinyl acetate copolymer was developed. The sintering technique produced nonerodible matrix tablets. The in vitro dissolution studies have shown a considerable sustained release of theophylline from the matrix tablets of different drug polymer ratios. The control of release of theophylline from the sintered tablets depended on the polymer-drug ratio, temperature of sintering and time of sintering. Tablet formulation with a drug-polymer ratio of 75:25 sintered at 60º for a period of 1.5 h gave maximum percent of drug release in 12 h. The cumulative percent of drug released from this tablet formulation is better than two commercial products and comparable to the other one.