Pharmacokinetics of isoniazid in pulmonary tuberculosis--a comparative study at two dose levels

Abstract

Objectives: To compare the pharmacokinetic parameters and the clinical efficacy of isoniazid, administered in 10 mg/kg or 5 mg/kg to children suffering from pulmonary tuberculosis.

Design: A randomized, open, controlled clinical trial.

Setting: Teaching hospital in New Delhi.

Subjects: Twenty children suffering from pulmonary tuberculosis in the age group 6-12 years.

Interventions: A three drug antitubercular regimen comprising of rifampicin (10 mg/kg), pyrazinamide (30 mg/kg) and isoniazid in a dose of either 10 mg/kg (Group I) or 5 mg/kg (Group II) was administered for fourteen days. On day fifteen serial blood samples were collected at 0,1,2,3,6 and 24 h of isoniazid administration and analyzed spectrofluorometrically.

Main outcome measures: Serum isoniazid concentrations and clinical response in both the groups.

Results: In both the groups, serum concentration of isoniazid were above the therapeutic range (0.5-2 micrograms/ml) at 6 h following drug administration. The minimum serum concentration of isoniazid was within or above minimum inhibitory concentration of the drug at 24 h in both the groups. The time to achieve maximum serum concentration, elimination half life, elimination rate constant, mean residence time, volume of distribution at steady state and plasma drug clearance were also comparable. At the end of 6 months follow up, all children showed comparable clinical and radiological improvement.

Conclusion: Isoniazid in a dose of 5 mg/kg administered with other antitubercular drugs appears adequate for treatment of pulmonary tuberculosis in children.