In-vitro binary release kinetics of sulphamethoxazole and trimethoprim microcapsules.

Sulphamethoxazole and trimethoprim are separately microencapsulated with polyacrylic resin: Eudragit RS 100. The data so obtained from the drug release have been analyzed according to the different existing kinetic models (1) Zero order (2) First order and (3) Higuchi Matrix Kinetics. It is observed that in both the cases of single component and binary release of sulphamethoxazole (SMZ) and trimethoprim (TMP), Higuchi mechanism predominates. Lastly, a comparative study is made between The Single and Binary release kinetics to correlate the diffusivity rate constant (KBL) and diffusion Coefficient (Da) which have been estimated according to Baker-Lonsdale method at pH 1.2.