Clinical trial of six-month and four-month regimens of chemotherapy in the treatment of pulmonary tuberculosis.

In a study in Singapore, Chinese, Malay, and Indian patients with pulmonary tuberculosis received 2 months of daily treatment with streptomycin, isoniazid, rifampin, and pyrazinamide followed either by daily treatment with isoniazid, rifampin, and pyrazinamide (SHRZ/HRZ regimen) or by daily administration of isoniazid and rifampin (SHRZ/HR regimen) allocated at random. Both regimens were given for either 6 or 4 months by random allocation. All 330 patients with drug-sensitive tubercle bacilli before treatment had a favorable bacteriologic response during chemotherapy. During the first 6 months after the end of chemotherapy, there was only a single bacteriologic relapse among 84 SHRZ/HRZ and 80 SHRZ/HR patients treated for 6 months, but 8 (10 per cent) of 80 SHRZ/HRZ and 4 (5 per cent) of 74 SHRZ/HR patients treated for 4 months relapsed. Of a total of 33 patients with bacilli resistant to isoniazid, streptomycin, or both drugs before treatment, only one had an unfavorable response during chemotherapy, and none of 31 patients relapsed during the first 6 months after stopping chemotherapy. The incidence of adverse reactions was low; 11 (3 per cent) of 397 patients had hepatitis, but not all episodes were attributable to drug toxicity, and one patient had thrombocytopenic purpura.