Design, development and evaluation of chronomodulated drug delivery systems of amoxicillin trihydrate with enhanced antimicrobial activity.

The present studies entail the formulation development and evaluation of chronomodulated drug delivery system of amoxicillin trihydrate (AMT), which comprises of a bilayer tablet containing a delayed release and a sustained release layer. Direct compression method was employed for the preparation of bilayer matrix tablets containing rational blend of polymers, such as Eudragit-L100 D55 as delayed release polymer and HPMCK4M, HPMCK15 and HPMCK100 are sustained release polymers. In- vitro drug release studies of bilayer tablets observed a good sustained release action with time-dependent burst release after a lag-time of 3 hrs. Evaluation of drug release kinetics from sustained release layer of bilayer tablets followed Higuchi model via quasi-Fickian diffusion mechanism. SEM studies revealed formation of pores on sustained release layer, which confirmed the drug release through diffusion and predominantly by surface erosion mechanism. Evaluation of antimicrobial activity showed a decrease in minimum inhibitory concentration of optimized bilayer tablets vis-à-vis conventional marketed formulation. Accelerated stability studies revealed that the optimized bilayer tablet formulation was found to be stable upto the period of 6 months. Solid state characterization employing FT-IR and DSC studies indicated lack of significant interaction of drug with formulation excipients. Thus, the present studies ratify the suitability of chronomodulated bilayer tablets of AMT for effective management of bacterial infections owing to specific time-dependent drug release, higher gastric protection and enhanced antimicrobial activity.