Abstract: AimThe simplified preparative method and formulation for atenolol monolithic osmotic pump tablets were investigated. MethodsThe core tablets with an indentation were compressed by the punch with a needle. Osmotic pump tablets were prepared by coating the indented tablets. Similarity factor was used to evaluate formulation of osmotic pump tablets. ResultsThe formulation of core tablets and the composition and thickness of coating membrane showed marked effects on drug release. Orifice size of core tablets in the range of 1.00-1.14 mm scarcely affected drug release. ConclusionThe preparation of osmotic pump tablets was simplified with the exempting of laser drilling. The atenolol monolithic osmotic pump tablets could deliver drug constantly for 24 h.