Metronidazole: Alcohol intolerance (disulfiram-like reaction) w/ alcohol. Increased risk of cardiotoxicity w/ amiodarone. Inhibited metabolism & increased plasma conc of astemizole & terfenadine. Increased carbamazepine blood conc. Increased blood level & risk of neurologic side effects w/ cimetidine. Increased risk of cyclosporine toxicity. CNS related effects w/ disulfiram. Increased blood levels & toxicity of lithium; fluorouracil. Increased blood levels w/ phenytoin & oral anticoagulants. Decreased blood levels w/ phenobarb. Interference w/ blood levels of liver enzymes, glucose (hexokinase method), theophylline & procainamide. Miconazole nitrate: Increased bleeding risk w/ acenocoumarol, anisindione, dicumarol, phenindione, phenprocoumon & warfarin. Inhibited metabolism & increased plasma conc of astemizole, cisapride & terfenadine. Decreased carbamazepine metabolism. Increased cyclosporine toxicity risk. Increased or prolonged opioid effects of fentanyl. Increased toxicity of phenytoin, fosphenytoin; trimetrexate. Increased hypoglycemic action of glimepiride. Increased plasma conc or exposure to oxybutynin. Increased plasma conc & reduced clearance of oxycodone. Increased risk of cardiotoxicity w/ pimozide. Increased tolterodine bioavailability in patients w/ deficient CYP450 2D6 activity.