Solubility-modulated monolithic osmotic pump tablet for atenolol delivery

A method for the preparation of monolithic osmotic pump tablet was obtained by modulating atenolol solubility with acid. Tartaric acid was used as solubility promoter, sodium chloride as osmotic agent and polyvinyl pyrrolidone as retardant agent. Ethyl cellulose was employed as semipermeable membrane containing polyethylene glycol 400 as plasticizer. The formulation of atenolol monolithic osmotic pump tablet was optimized by orthogonal design and evaluated by similarity factor (f2). The optimal monolithic osmotic pump tablet was found to be able to deliver atenolol at the rate of approximate zero-order up to 24 h, independent of release media and agitation rate. The approach of solubility-modulated by acid-alkali reaction might be used for the preparation of osmotic pump tablet of other poorly water-soluble drugs with alkaline or acid groups.