The objective of the present investigation was to develop controlled release matrix pellets of venlafaxine HCl using the concept of design of experiments. Extrusion-spheronization technique was adopted for the preparation of the matrix pellets of venlafaxine HCl employing ethyl cellulose (EC) and polyethylene oxide (PEO) as insoluble and soluble matrixing agents respectively. Hydroalcoholic fluid was used as a binder to facilitate pellet formation. The pellets were assessed for flow property and friability. Media change method was used to study the in vitro dissolution pattern of venlafaxine HCl. Model fitting was carried out to identify the most valid kinetics of drug release. The use of hydroalcoholic medium, in place of water, facilitated processing without sticking. The pellets exhibited good flow and low friability. The drug was released at a controlled rate from the formulated product. Multiple regression analysis was used to evolve mathematical models for drug release at 2, 6 and 12 hr. Response surface plots were drawn to visualize the impact of independent variables on drug release. The drug release at 2, 6 and 12 hr was influenced by the amount of EC and PEO. The kinetics of drug release was best explained by Weibull model. The drug was released by nonfickian diffusion. The use of systematic formulation study is advantageous for the development of CR pellets of venlafaxine HCl. The optimum batch consisted of 37.5 mg venlafaxine HCl, 30% EC and 20% PEO.
Venlafaxine hydrochloride, matrix pellets, PEO, ethyl cellulose, factorial design
