Discrepancy among dissolution rates of commercial tablets as a function of dissolution method. part 6: rifampicin.

The dissolution rate of six batches of commercial rifampicin products manufactured by three pharmaceutical companies was determined by both closed and open dissolution systems. The most consistent results were those obtained by the beaker method. Inter-batch as well as inter-brand variation in dissolution were found to be more evidently detected and evaluated by adopting the beaker and flow-through methods. The biovailability of these products was assessed in human subjects according to a cross-over design system. Based on the values of the correlation coefficient of the in vitro results obtained by different dissolution methods with the in vivo results, the USP rotating basket method appears to correlate best with maximum urinary excretion rate, area under excretion rate versus time curve as well as total amount of drug excreted. Thus, determination of the dissolution rate of rifampicin products by the USP rotating basket method can be considered as a reliable tool for predicting the in vivo performance of the drug.