The influence of different doses of isoniazid at the time of sputum smear conversion among patients with drug-sensitive pulmonary tuberculosis

The main aim of our study was to estimate the influence of different doses of isoniazid 5 and 10 mg/kg in the combination with the other antituberculosis drugs at the time of sputum smear conversion among patients with drug-sensitive pulmonary tuberculosis. We carried out cohort prospective study of 77 patients with new cases of tuberculosis or relapse. The patients received treatment in the 3 department of the Regional Clinical ТВ Dispensary, Arkhangelsk, since April, 2008 till Aprill, 2009. A comparative analysis on 2 regimens of antituberculosis treatment was carried out. It included: rifampicin (10 mg/kg), pirazinamid (30 mg/kg), etambutol (25 mg/kg) and isoniazid 5 mg/kg (group 1) or 10 mg/kg (group 2). At the end of the intensive phase of treatment intoxication and clinical manifestations disappeared in all the patients of group 1 and group 2. The mean time from the initiation of appropriate therapy to sputum smear conversion in two groups were approximately the same (Me=3,00, Q1=1,00, Q3=8,50 и Me=3,00, Q1=1,00, Q3=7,00).The patients from group 1 and group 2 had the same rates of sputum smear conversion at the 1 week (RR=0,938, 95%Ci=0,468-1,635) and at the 1 month of treatment (RR=1,036, 95%CI=0,741-1,447). By the end of the intensive phase (3 month) 35 (79,8%) patients from groupl and 30 (90,9%) patients of group 2 have converted by smear (RR=0,875,95%C1=0,727-1,052). By the end of intensive phase all patients reached sputum culture conversion and had positive radiological changes. The patients in both groups, where different doses of isoniazid (5 and 10 mg/kg) in the combination with other antituberculosis drugs were used, demonstrated a high effectiveness of treatment. No statistically significant differences in the time of sputum smear conversion in both groups were found.