Aspirin--a national survey IV: In vitro dissolution of aspirin formulations.

The results of a national survey of the in vitro dissolution rates of aspirin tablets are presented. Dissolution profiles by both the proposed USP XX basket method and a paddle method are compared. The methods were used to analyze 59 tablet formulations representing 38 manufacturers. Each tablet was subjected to the dissolution procedure in 500 ml of pH 4.5 buffer solution, and an aliquot was sampled automatically and analyzed by an automated system. In 30 min, 22% of the samples tested using the basket method failed the proposed USP XX dissolution requirement. Seventy-five percent of the samples tested By the paddle method also failed the proposed dissolution requirement.