Dosage of antituberculous drugs in obese patients

There are no published data defining efficacious drug therapy for obese patients with active tuberculosis. Current dosage recommendations are based on total body weight (TBW); drug toxicity might result in obese patients receiving TBW doses. Peak and trough serum levels were measured for rifampin, streptomycin, ethambutol, and pyrazinamide in an obese patient (166 kg TBW, 87 kg ideal body weight (IBW] with miliary and meningeal tuberculosis. The observed drug levels and the calculated serum half-lives of these drugs were compared with the expected serum levels and serum half-lives in lean patients treated with literature-recommended doses. The observed serum levels in our obese patients were within the expected range for lean patients when dosage was based on IBW rather than on TBW. The observed cerebrospinal fluid penetrations of the drugs studied in our obese patient were similar to those reported in lean patients.