Design space.

Verapamil hydrochloride has a short half-life 2.8 to 7.4 hours, a narrow absorption window and is mainly absorbed in proximal areas of GIT. The present investigation aimed to formulate a floating drug delivery system of Verapamil Hydrochloride by Quality by design approach. In risk assessment, the effects of process and formulation variables on particle drug release and floating lag time were investigated. Design of experiments (DoE) and multivariate data analysis were used to identify important process and formulation parameters. A 22 factorial design in replicate was employed to produce controlled release floating tablet. The effect of critical formulation variables i.e. levels of HPMC K15M and gas generating agent (i. e. Sodium bicarbonate and citric acid) on % Drug release after 12 hr (% DRel12) and floating lag time (FLT) were analyzed. Verapamil HCl tablets were evaluated for hardness, friability, weight variation, drug content, floating behavior and drug release studies were conducted in 0.1 N HCl (pH 1.2) at 37 ± 0.5OC. The tablets showed acceptable physicochemical properties. The two independent variables studied exhibited a significant influence (P < 0.05) on % DR 12 Hr and FLT. Numerical and graphical optimization technique employing design space approach was used to develop a new formulation by setting constrains on the dependent and independent variables. The experimental values of % DR 12 Hr and FLT for optimized batch were found to be in close agreement with those predicted by mathematical model. Experimental values obtained from the optimized formulations were in both cases close to the predicted values, thus confirming the validity of the generated mathematical model. These results demonstrated the effectiveness of the proposed floating tablet, as well as the usefulness of the QbD approach for the development of Verapamil floating tablet with optimized properties.