[Simultaneous study of the induction effect of rifampicin and the phenotype for acetylation of isoniazid in 21 patients with tuberculosis undergoing a combination treatment].

Enzyme induction during an antituberculous treatment with Rifampin, Isoniazid and Ethambutol was studied in 21 patients with tuberculosis. Two tests were used: increase in urinary excretion of D-saccharic acid and decrease of the half-life of antipyrineee. Induction is constant with D-saccharic acid. On the other hand there is a significant decrease in the half-life of antipyrin in only 10 patients. There is an increase in the 11 other patients: all of them are slow acetylators for isoniazid. We suggest that INH has an inhibitor effect on the hydroxylation of antipyrin. This study allows us to discuss the interactions of drugs with INH and Rifampin, as well the predominance of rapid acetylators among subjects suffering of isoniazid hepatitis, recently questioned.