Rifabutin for the treatment of newly-diagnosed pulmonary tuberculosis: a multinational, randomized, comparative study versus Rifampicin. Rifabutin Study Group.

SettingPatients with newly-diagnosed drug-sensitive, radiographically active and bacteriologically confirmed pulmonary tuberculosis recruited at 6 centres in Argentina, Brazil and Thailand.ObjectiveTo assess the efficacy, tolerability and toxicity of two regimens containing different daily dosages of rifabutin in comparison with rifampicin.DesignMulticentred, randomised, comparative study. In each group, study medications were administered daily for 6 months combined with isoniazid (6 months), and with pyrazinamide and ethambutol (both stopped after 2 months). Treatment success patients were followed-up for up to 2 years.ResultsA total of 520 patients were enrolled and randomly assigned to receive either rifampicin (n = 175), or rifabutin 150 mg (n = 174) or rifabutin 300 mg (n = 171). Considering all patients with positive baseline culture, the success rates at the last valid observation for each patient were 89%, 94% and 92% in the rifampicin, rifabutin 150 mg, and rifabutin 300 mg groups, respectively. The median time to culture conversion was comparable in the 3 groups and was 34 days for rifampicin and 37 days for each of the rifabutin groups. During the drug-free follow-up period, one relapse occurred in the rifampicin group, and two in each of the rifabutin groups. The 3 treatment schedules appeared well tolerated. No patients had to discontinue therapy because of an adverse event in the rifabutin 150 mg group, compared to one in the rifampicin and 5 in the rifabutin 300 mg group.ConclusionAll 3 regimens proved effective and well tolerated. Rifabutin at 150 mg/d showed the best risk-to-benefit ratio, in that this group had the highest proportion of patients completing treatment, the highest bacteriological conversion rates and the lowest incidence of adverse events.