A study was carried out to investigate the applicability of INH-Thiacetazone (TH) combination with special reference to acceptability and toxicity in Tumkur district. 150 patients from Tumkur town and some nearby villages were discovered during a mass Case-finding programme. Of them, 127 including 43 sputum positives were given chemotherapy with 300 mgm INH and 150 mgm thiacetazone (TH), in a single tablet to be taken once a day. All but one patient had the treatment on an ambulatory basis. Results of treatment in respect of 103 patients are presented in the paper.

The overall death rate was of the order of 15%. About twice the number of deaths occurred among the sputum positive patients than among the negative ones. About 40% of deaths occurred during the first quarter. In all, 23 patients developed side effects, in 18 of them thiacetazone had to be withdrawn. Serious side effects occurred among 5 (4%) patients. These patients did not report to the treatment centre by themselves and could not have been detected, if home visits were not made, thus giving an erroneous impression about side effects with TH. The sputum conversion at the end of one year was of the order of 50% among all survivors. Among those who were drug sensitive and examined at one year, conversion rate was 63%. Favourable radiological response was seen in 74%.

Thus, though cheap and clinically effective, Thioacetazone in combination with INH was found to produce serious and significant side effects. Hence, vigilance by the treatment centres were thought to be necessary when the patients are on this regimen.