BIOAVAILABILITY OF CHINESE RIFAPENTINE DURING A CLINICAL-TRIAL IN HONG-KONG

SETTING: A clinical trial of rifapentine in Hong Kong. OBJECTIVE: Asse ssment of the bioavailability of the Chinese rifapentine used in the t rial. DESIGN: The content of rifapentine in serum samples taken from 2 87 patients during the administration of four batches of the drug was measured by microbiological assay. RESULTS: An initial comparison of a reas under curve obtained in a random allocation to 40 patients of rif apentine either of Western or Chinese origin indicated that the bioava ilability of the Chinese drug was 74% of the Western drug. The bioavai lability of the second batch was found to be about 66% of the Western drug. The dose of the last two batches of rifapentine was therefore in creased from the planned 600 mg to 750 mg, or briefly to 900 mg; serum concentrations were then similar to those obtained with the Western d rug. Bioavailability did not change during the use of each drug batch. CONCLUSION: A comparison of the results obtained in the trial with th e initial two batches and the final batches will estimate the effects of rifapentine dose size on its efficacy and toxicity.