In response to letter from Sahu, we wish to inform that: (a) the group extensively deliberated about appropriate doses for anti-TB drugs to be recommended for our country based on available evidence and concluded that the earlier recommended dosages needed revision. The current dosages were arrived after looking into various available pharmacokinetic data and evidence within and outside the country (published and unpublished data from studies at AIIMS and NIRT). The group arrived at these recommendations as a consensus, while keeping in mind the absolute need for adequate serum levels and also the possible risk of cumulative hepatotoxicity; (b) the group recommends the total duration of ATT in intracranial TB including TB Meningitis should be 9-12 months depending upon the clinical progress on treatment. This is in consonance with available evidence and experience; and (c) among retreatment cases, the INH resistance is significant but not absolute, hence a third drug ethambutol, is added to in the continuation phase (RHE). There is no scientific basis or evidence for including pyrazinamide instead of ethambutol in the continuation phase. Pyrazinamide works best when there is active inflammation and in acidic pH, hence its benefit may not be seen during the continuation phase [1]. Furthermore, addition of Ethambutol not only helps in preventing emergence of drug resistance [2] but also would minimize the potential risk of hepato-toxicity with prolonged use of the suggested three hepatotoxic drugs (RHZ).

1. Snider DE Jr. Controlled clinical trial of four 6-month regimens of chemotherapy for pulmonary tuberculosis. Second East Africal/British Medical Research Council Study. Am Rev Respir Dis. 1976; 114:471-75.