Modulation of drug release by utilizing pH-independent matrix system comprising water soluble drug verapamil hydrochloride.

The present study was undertaken to investigate the effect of hydrophilic, plastic and hydrophobic types of polymers and their content level on the release profile of drug from matrix systems. To improve therapeutic efficacy, systemic absorption and patient compliance a sustained release matrix tablets of Verapamil HCl (VHE) has been developed. VHE tablets were prepared by using various polymers like hydrophilic (HPMC K15M CR), plastic (Kollidon SR), hydrophobic (Eudragit RSPO) and combination of best two resulted polymers using direct compression. A 32 full factorial design was applied to study the effect of polymers on drug release. For the combination of polymers, selected factors HPMC K15 CR (X(1)) and Eudragit RSPO (X(2)) showed positive influence on drug release at 18 hrs and 20 hrs. The release profile of VHE formulation exhibits Higuchi model with anomalous diffusion release. Accelerated stability trials for 3 months proved reproducibility. A good correlation between the dissolution profiles and bioavailability indicated a linear relationship between in vitro - in vivo data. The current study attained the successful design, development and optimization of controlled release once-a-day formulation of VHE.