Release kinetics of sulfadimidine sodium and trimethoprim from tablets containing different excipients prepared by wet granulation method

Abstract

In this study seven tablet batches were prepared by wet granulation process using different excipients such as: superdisintegrant – croscarmellose sodium (Ac- Di- Sol), silicon dioxide (Aerosil), lactose, pregelatinized starch (CPharm Gel) and microcrystalline cellulose (Avicel pH- 101). Sulfadimidine sodium (SDD-Na) and trimethoprim (TMP) were used as model active substances. Tablets were evaluated for uniformity of weight, hardness, friability, drug content, disintegration time and dissolution properties. To study the release kinetics of the drugs, data obtained from in vitro drug release studies were plotted into the following kinetic models: zero order, first order, Higuchi, Hixson-Crowell and Korsmeyer-Peppas. The obtained results demonstrate that SDD-Na release kinetics was best described by Higuchi model followed by first order model. TMP release kinetics was best explained by first order model followed by Higuchi model. The Hixson-Crowell plot showed good linearity for SDD-Na and TMP. Release exponents values for Korsmeyer-Peppas model were characteristic for anomalous transport (non-Fickian) which appears to indicate a coupling of the diffusion and erosion mechanism or super case II transport refers mainly to the erosion of the polymeric chain.