Labelled Isoniazid. Antibiotic for treatment of Mycobacterium tuberculosis, inhibits mycolic acid biosynthesis. Metabolized by hepatic N-acetyltransferase (NAT) and cytochrome P450 2E1 (CYP2E1) to form hepatotoxins. Selectively induces expression of CYP2E1. Reversibly inhibits CYP2C19 and CYP3A4 activities, and mechanistically inactivates CYP1A2, CYP2A6, CYP2C19 and CYP3A4 at clinically relevant concentrations. Antibacterial (tuberculostatic).