Table 7.

Metronidazole Drug Interactions

Drug	Cytochrome Association	↑ Levels of CYP3A4 Substrates	Other Drug-Drug Interaction	Renal Impairment
Metronidazole	Inhibits CYP: 3A4 (moderate) 2C9 (weak)	benzodiazepines calcium channel blockers cyclosporine mirtazapine nateglinide nefazodone sildenafil (and other phosphodiesterase type 5 inhibitors) tacrolimus venlafaxine cisapride ergot alkaloids 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors (lovastatin, simvastatin) pimozide	Cimetidine: increase levels of metronidazole Cisapride: proarrhythmic due to inhibition of metabolism Ethanol: disulfiram-like reactions Lithium: may increase lithium levels/toxicity Phenytoin, phenobarbital: may increase metabolism of metronidazole Warfarin: increases prothrombin time prolongation	Inconsistent recommendations; consider dosage reduction in longerterm therapy with severe renal failure (CrCl <10 mL/minute)

CrCl

creatinine clearance.