Discrepancy among dissolution rates of commercial tables as a function of the dissolution method. Part 7: Aspirin.

The dissolution rate of fifteen batches of commercial aspirin tablets manufactured by five leading pharmaceutical companies was determined by closed and open dissolution systems. The most consistent results were those obtained by the USP method. Inter-batch as well as inter-brand variations were found to be more evidently detected and evaluated by adopting the USP and beaker methods, respectively. The bioavailability of these products was assessed in human subjects according to a cross-over design system. The following pharmacokinetic parameters for the drug were computed, viz., maximum excretion rate, elimination rate constant, half-life time, area under excretion rate versus time curve and total amount of drug excreted during 24 h following administration of a single oral dose. Based on the values of the correlation coefficient of the in vitro results obtained by different methods with the in vivo results, the beaker method appears to correlate best with the area under excretion rate versus time curve and total amount of drug excreted. Thus, determination of the dissolution rate of aspirin tablets by the beaker method can be considered as a reliable tool for predicting the in vivo performance of the preparation.