Bioequivalence study of nalidixic acid tablets: in vitro-in vivo correlation.

The USP dissolution test was used to select seven products with a wide range of dissolution characteristics for in vivo examination. The bioequivalence of seven (500 mg) products was evaluated in two crossover urinary excretion experiments. In each study three products were compared with the innovator product (Negram-Winthrop-Breon) in 12 subjects according to a 4 x 4 latin square design. Significantly different, lower bioavailability was observed in two products in relation to that of the innovator product. Linear in vitro-in vivo correlations were found between the cumulative amount excreted at 24 h and the log of the amount dissolved at 30 min and between log of the cumulative amount excreted up to 24 h and the log of the amount dissolved at 45 min.