FORMULATION AND EVALUATION OF CONTROLLED POROSITY OSMOTIC TABLET OF VERAPAMIL HYDROCHLORIDE

Verapamil hydrochloride is a water-soluble drug, so it is suitable to develop controlled porosity osmotic pump.  As Verapamil HCl is a short-acting drug, so developed formulation provides the advantages of controlled release formulations. The developed formulation provides advantages of less steps of manufacturing procedure, no need for laser drilling, and economical, all of which made the procedure easily amenable to mass production using conventional tablet machines. Verapamil HCl 120 mg core formulations were prepared coated with film former (cellulose acetate): pore former (sorbitol). The effect of different formulation variables, namely, membrane weight gain, and amount of pore former in the membrane, were studied. Verapamil HCl release was inversely proportional to the membrane weight (coating thickness) but directly related to the initial amount of pore former (sorbitol) in the membrane. Drug release from the developed formulations was independent of pH but dependent on the osmotic pressure of the release medium. Verapamil HCl release from the developed formulation follows zero-order. The drug release from formulation was proved as dependent on osmotic pressure only. Results of SEM studies showed the formation of pores in the membrane after coming in contact with aqueous dissolution fluid from where the drug release occurred. The manufacturing procedure was found to be reproducible, and formulations were stable after three months of accelerated stability studies.