ABSTRACT
<p><b>AIM</b>The simplified preparative method and formulation for atenolol monolithic osmotic pump tablets were investigated.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSION</b>The 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.</p>