Bioavailability of rifampicin caplets (600 mg and 450 mg) in healthy Indonesian subjects

A bioavailability study of rifampicin 450 mg caplets and rifampicin 600 mg caplets was carried out in 20 healthy male subjects. The higher dose was administered to subjects with a body weight greater than 50 kg. Subjects were divided into two groups where group 1 was treated with a single oral dose of 450 mg rifampicin in fasting condition. Group 2 was treated in the same way as group 1, but with a dose of 600 mg rifampicin. Our results in group 1 show peak heights of serum levels of rifampicin ranging from 13.6 to 21.0 μg·ml^-1 (mean value was 17.6 μg·ml^-1). AUC values ranged from 81.1 to 177.9 μg·ml^-1h (mean value was 145.2 μg.·ml^-1h). Respective figures with 600 mg rifampicin were 11.0 to 27 μg·ml^-1 (mean = 20.0 μg·ml^-1) for peak heights and 132.0 to 260.6 μg·ml^-1h (mean value = 181.1 μg·ml^-1h) for AUC. In vitro dissolution tests were conducted on the same batch of respective products. Results show that maximum dissolution occurred in 15 minutes. It is concluded that our results were rather high compared to what has been reported so far. It has been suggested to reduce the dose to body weight ratio for rifampicin.