Designing and Evaluation of Floating Microspheres of Verapamil Hydrochloride: Effect of Methocel

The floating microspheres have been utilized to obtain prolonged and uniform release in the stomach for development of a once daily formulation. The major advantage of the preparation technique includes short processing time, the lack of exposure of the ingredients to high temperature and high encapsulation efficiencies. The aim of present investigation was to prepare and evaluate gastroretentive floating microspheres of verapamil hydrochloride that would retain the drug in stomach and continuously release the drug in controlled manner. Floating microspheres were prepared by emulsion solvent evaporation technique. In the present investigation three polymers were used in various concentrations; Methocel K4M, Methocel K15M and Methocel K100M. In vitro performance was evaluated by the usual pharmacopoeial and other tests such as particle size analysis, drug entrapment efficiency, flow properties, in vitro floatability studies, in vivo floatability studies in dog, in vitro drug release studies, stability studies etc. Results showed that the mixing ratio of components in the organic phase affected the size distribution, yield, drug content, floating time and drug release of microspheres. In vitro drug release studies were performed for all the prepared formulations. Rank order for percentage cumulative drug release was found to be Methocel K4M > Methocel K15M > Methocel K100M. In most cases good in vitro floating behavior was observed and a variety of drug release pattern could be achieved by variation of the drug, polymer and solvent ratio. The developed floating microspheres of Verapamil hydrochloride may be used for prolonged drug release in stomach for more than 8 h.