ISONIAZID LEVELS IN THE BRONCHOALVEOLAR LAVAGE FLUID OF PATIENTS WITHPULMONARY TUBERCULOSIS

Isoniazid (INH) is one of the most important first fine drugs in the t reatment of tuberculosis. We utilized high performance liquid chromato graphy with a hydrazone extraction technique to measure WH in bronchoa lveolar lavage (BAL) fluid specimens from six patients with active pul monary tuberculosis. We found BAI, fluid INR levels to be similar to 2 -h peak serum levels. The concentration of INH in BAL fluid from lobes with infiltrate was similar to the concentration of INH in BAL fluid from lobes without infiltrate (0.062 mu g/ml and 0.073 mu g/ml, respec tively). After adjusting for protein concentration in the BAL fluid, I NH levels in lobes with infiltrate were threefold lower than in lobes without infiltrate. The correlation between the concentration of INH i n serum and BAL fluid approached significance after correcting for pro tein (lobes with infiltrate, r(2) = 0.60 (p = 0.07); lobes without inf iltrate, r(2) = 0.50 (p = 0.12)). INH penetrates into bronchoalveolar fluid, and concentrations of INH in the BAL fluid suggest that assessm ent of the INH serum concentration is adequate to evaluate bioavailabi lity of the drug in patients with pulmonary tuberculosis.