Isoniazid (INH) is an essential component of first-line anti-tuberculosis (TB) treatment. However, treatment with INH is complicated by polymorphisms in the expression of the enzyme system primarily responsible for its elimination, N-acetyltransferase 2 (NAT2), and its associated hepatotoxicity. The objective of this study was to develop an individualized INH dosing regimen using a pharmacogenetic-driven model and to apply this regimen in a pilot study.

• Eligible participants were patients newly diagnosed with active TB
• Who underwent standard four drug treatment for 6months: isoniazid (5 mg/kg, usually 300 mg), rifampin (450 mg for <50 kg or 600 mg for 50 kg body weight), ethambutol(15mg/kg), and pyrazinamide (20 - 30 mg/kg)
• Given daily for two months and followed by isoniazid and rifampin with or without ethambutol for four months.
• Those patients with abnormal hepatic function on laboratory testing (increased serum aspartate aminotransferase, alanine aminotransferase, or total bilirubin) before anti-TB treatment, underlying liver disease or systemic illness such as congestive heart failure, acute life-threatening disease, or alcoholism, or disease that was resistant to INH at the start of treatment were excluded.