Abstract

Alternate copolymers of n-butyl methacrylate and maleic anhydride were prepared and characterized. Amoxycillin was bound on copolymers through pendent anhydride groups by chemical bonding. In vitro release rates were investigated in 0.1 M phosphate buffer solution with varying pH at 37 ⁰ as well as in biological media. The release rates of the investigated model drug molecules followed first order kinetics and were dependent on buffer concentration and pH. It was observed that molecular weight of copolymers varied from 8000 to 22,000 g/mol and duration of the delay period prior to release increased from 6 to 9 d. P(BMA-MA-1) showed increase in cumulative release rate with increase in pH unit from 3.8 to 7.2, which further decreased from pH 7.8 and 8.0, respectively. With P(BMA-MA-2) gradual increase in release activity was observed in acidic range and in neutral to alkaline condition (pH 7.0 to 8.0) the release activity lasted for 7 to 9 d respectively. Similar condition for P(BMA-MA- 3) showed cumulative release activity for 9 d in acidic pH, which further decreased to 7 d from pH 7.0 to 8.0. P(BMA-MA-1, 2 and 3) showed maximum inhibition of 40%, 59.3% and 72.8% towards Bacillus subtilis, 40%, 44% and 65.4% inhibition against Staphylococcus aureus and 41.2%, 51.7% and 69.1% inhibition against Escherichia coli at 48 h of incubation.