Isoniazid plus thioacetazone compared with two regimens of isoniazid plus PAS in the domiciliary treatment of pulmonary tuberculosis in South Indian patients.

Previous reports from the Tuberculosis Chemotherapy Centre, Madras, have established that ambulatory treatment of pulmonary tuberculosis with a standard daily regimen of isoniazid plus PAS for one year yields satisfactory results. However, this regimen may be unsuitable for large-scale use in many developing countries, because PAS is expensive, bulky and unpleasant to take, and has poor keeping qualities, especially in tropical countries. It might be possible to overcome these disadvantages, by substituting for the PAS a drug which is equally effective but less expensive and more acceptable, or by reducing the daily dosage of PAS and the period for which it is prescribed.This paper presents the results over a 12-month period of a controlled comparison of (a) the standard regimen of isoniazid (average 4.5 mg/kg body-weight) plus sodium PAS (average 0.22 g/kg), daily in two divided doses; (b) a regimen of isoniazid (average 6.9 mg/kg) plus thioacetazone (average 3.4 mg/kg), daily in one dose; and (c) a 2-phase regimen of isoniazid (average 5.5 mg/kg) plus sodium PAS (average 0.17 g/kg), daily in one dose for 6 months, followed by isoniazid alone (average 6.8 mg/kg), daily in one dose for the second 6 months. The regimen of isoniazid plus thioacetazone was found to be therapeutically as effective as the standard regimen of isoniazid plus PAS; however, it was associated with a higher incidence of minor side-effects, and three cases of exfoliative dermatitis. The 2-phase regimen of isoniazid plus PAS followed by isoniazid alone was less effective.These findings are encouraging for the large-scale use in developing countries of the relatively inexpensive regimen of isoniazid plus thioacetazone; however, any such step should be preceded by carefully planned studies to investigate, under local conditions, the toxicity and the efficacy of the regimen.