Objective: To document the pharmacokinetics and serum concentrations of first-line anti-tuberculosis drugs in adult Turkish patients with pulmonary tuberculosis (PTB).
Design: Consenting 21 adult patients (aged 38 ± 4 years, 10 female and 11 male) with newly diagnosed active PTB participated in the study. Blood samples were collected 1, 2, 4, 6 and 24 h after simultaneous isoniazid (INH), rifampicin (RMP), pyrazinamide (PZA) and ethambutol (EMB) ingestion. Serum concentration-time profiles, maximum serum concentrations, time to achieve maximum serum concentrations, the half-life and the areas under the serum concentration-time curve for each of the four drugs were determined.
Results: Wide variations in pharmacokinetic parameters were observed among patients. In respectively 8 (38%), 17 (81%), 3 (14%) and 1 (5%) patients, the maximum INH, RMP, PZA and EMB serum concentrations were below the accepted therapeutic concentrations.
Conclusion: Our data show that the serum concentrations of anti-tuberculosis drugs varied considerably in the study patients. Therapeutic drug monitoring is necessary to identify patients with subtherapeutic INH and RMP serum concentrations.