Preparation and in vitro Evaluation of Sustained Release Drug Delivery System for Verapamil HCl

Ion exchange resins have versatile properties as drug delivery vehicles and have been extensively studied in the development of novel drug delivery systems1. Cation exchange resins containing strong sulfonic acid group form a strong bond with cationic drugs and elution of drug from resinates is slower2. Formulations based on ion exchange resins are successfully marketed viz Pennkinetic system by Pennwalt Corporation, USA, marketed as Pentuss®. It contains codeine and chlorpheniramine, both complexed with cation exchange resin, where the chlorpheniramine resinate is uncoated and codeine resinates particles are coated with release controlling ethyl cellulose membranes3. Sustained release resinate of 5-fluorouracil4, chlorpheniramine maleate5 and phenylpropranolamine6 have been described. Micro particulates of ion-exchange resin drug complex have also been used for ophthalmic drug delivery of betaxolol, an antiglaucoma agent7. Manek and Kamat8 evaluated Indion CRP–244 and CRP–254 resins as sustained release and taste masking agents. In these systems, drug loaded on the resin dissociates slowly in GI fluids to give sustained release and resinates are incorporated in matrix to retard the release9. Physical mixture of drug and ion exchange resin form complex in situ which release drug with same rate as preformed resinates10. Attempts to coat resinate with rate controlling barrier have successfully obtained controlled release11,12. Objective of present work is to prepare sustained release resinates of verapamil HCl. Resinates are further pelletized by extrusion spheronization obtain desired release.