Metronidazole: Disulfiram-like reaction w/ alcohol. Increased oral anticoagulant effect, blood levels of phenytoin, lithium toxicity, plasma conc of astemizole & terfenadine; blood conc of carbamazepine. Decreased blood levels w/ phenobarb. Risk of CNS-related effects (eg, psychotic reactions) w/ disulfiram. Increased blood levels & neurologic effects w/ cimetidine. May increase blood levels & toxicity of fluorouracil; toxicity of cyclosporine. Increased cardiotoxicity w/ amiodarone. Interference w/ blood levels of liver enzymes, glucose (hexokinase method), theophylline & procainamide. Decreased levels w/ phenytoin. Miconazole: Increased risk of bleeding w/ acenocoumarol, anisindione, dicumarol, phenindione, phenprocoumon, warfarin; plasma conc & exposure to oxybutinin. May increase risk of phenytoin, phosphenytoin, cyclosporine, trimetrexate toxicity & cardiotoxicity w/ pimozide. May inhibit metabolism of astemizole, cisapride & terfenadine. Reduced carbamazepine metabolism. Increased or prolonged effects of opioid (fentanyl). May cause hypoglycemia w/ glimepiride. Reduced clearance & increased plasma conc of oxycodone. May increase bioavailability of tolterodine (in patients w/ deficient CYP2D6 activity). Lidocaine:
Increased toxicity w/ antiarrhythmic products. Decreased plasma clearance w/ cimetidine & propranolol. Decreased plasma levels w/ phenytoin or barbiturates.