Controlled Release of Antipyrine from Tablets Using Synthesized Copolymers as Matrices in Gastric Medium

Introduction: In order to control and modify the drug release, several types of devices were used to obtain a controlled release of the organic drug. A drug delivery system can be a matrix of polymer incorporating the active agent. New solid dosage forms (tablets) composed from the active agent (Antipyrine) and copolymers synthesized: Poly (vinyl acetate-co-methyl methacrylate) and Poly (vinyl pyrrolidone-co-methyl methacrylate) able to control drug release have been prepared and investigated in this paper. Methods: These copolymers synthesized were characterized (FTIR, 13C RMN, Tg and Mv), solid dosage forms (tablets): T(VAc1), T(Vac2) and T(VP) composed from the active agent (AP) and copolymers synthesized: poly (VAc-co-MMA) and poly (VP-co-MMA) as matrices were elaborated. The drug release from these formulations are performed in a cylindrical double-wall glass reactor (100 mL), kept at a temperature of (37 ± 0.5)°C and was followed using UV-Vis spectrophotometer in acidic medium at pH 1.2. The effect of the matrix on the drug release was studied. Results: The drug dissolution from matrix tablets is significantly influenced by the nature of matrix. The results showed that after 2 h (the time corresponding to the drug retention in the human stomach), the percentages of the drug released from T(VAc1), T(Vac2) and T(VP) are 1.04 %, 0.37 %, and 36.89% respectively. The release is even greater when the matrix is hydrophilic. Swellable matrix tablets, such as poly (vinyl acetate-co-methyl methacrylate) tablets, are activated by water, and drug release is controlled by the interaction between water, polymer and drug. Theoretical analyses of the kinetics of controlled release of AP have been established and Antipyrine dissolution rate constants were calculated from Higuchi’srelease model and the n exponents from Korsmeyer–Peppas model were determinate. Conclusion: The suitable kinetics model for describing the release of AP from the matrix tablets was the Higuchi model. The coefficients of correlation r2 in this model are above 0.99. The results of the Korsmeyer–Peppas equation, the values of n are in agreement with the experimental results already reported.