Abstract: AimTo study unitary-core osmotic pump tablet for delivering water-insoluble drug for 24 hours. MethodsUnitary-core osmotic pump tablet was prepared using nifedipine as the model drug. The effects of various core formulation variables on drug release were studied. ResultsPolyethylene oxide and potassium chloride have comparable positive effects on drug release, whereas, nifedipine has markedly negative effect on drug release. ConclusionUnitary-core osmotic pump tablet is very easy in preparation and it can deliver water-insoluble drug in substantially constant rate for 24 hours.