Pharmacokinetic studies on antituberculosis regimens in humans. I. Absorption and metabolism of the compounds used in the initial intensive phase of the short-course regimens: single administration study.

The absorption and metabolism of streptomycin, isoniazid, rifampicin, and pyrazinamide were evaluated after administration of each drug alone and in combination. In the combination sessions, isoniazid, rifampicin, and pyrazinamide were administered orally, either individually or in a single fixed-ratio triple preparation. The results have shown that the pattern of absorption and metabolism (acetyl-isoniazid, desacetyl-rifampicin, and pyrazinoic acid) found after administration of each drug alone did not differ from that found after administration of the drugs in free and fixed combination. The 3 orally administered drugs given in a fixed combination resulted in a reduction of the order of 50% of the total number of tablets to be ingested.