Absorption of rifampin from various preparations and pharmaceutic forms.

The absorption of 9 rifampin preparations was measured in two seaparate crossover studies on 10 healthy female volunteers. In the first set of experiments, one of the three capsule preparations was absorbed more slowly than the other ones. The absorption of two syrup preparations was nearly twice that of the best capsule preparation. In the second set, the absorption of the commercial tablets appeared to be somewhat faster than that of the reference capsule preparation. One tablet dissolved slowly in vitro and yielded very low serum concentrations. On the basis of these results the equiactive dose of rifampin in syrup form may be 25% to 50% lower than that of the other forms.