Nitroimidazole — anaerobic bacteria + protozoa reduce the nitro group to a cytotoxic radical that fragments DNA. Disulfiram-like reaction with alcohol. Modest CYP3A4 inhibition raises warfarin INR.
Half-Life (t½)
PO: 8h, IV: 8h
Dosing Guidelines
PO: Typical 500 mg (Range: 250–750 mg)
Target Organ Systems
digestive
Interactions
Warfarin (major): CYP2C9 inhibition (S-warfarin selective). O'Reilly 1976 (PMID:934223): metronidazole significantly augmented S-warfarin levels and hypoprothrombinemia; no R-warfarin effect. Reduce warfarin dose or monitor INR closely during metronidazole courses.