Pharmaniaga Metronidazole Drug Interactions

Alcohol: It is recommended that metronidazole not be used concurrently with or for at least 1 day following ingestion of alcohol; accumulation of acetaldehyde by interference with the oxidation of alcohol may occur, resulting in disulfiram-like effect such as abdominal cramps, nausea, vomiting, headache or flushing; in addition, modifications in the taste of alcoholic beverages have been reported during concurrent use.
Anticoagulants, coumarin or indandione-derivative: Effects may be potentiated when these agents are used concurrently with metronidazole, because of inhibition of enzymatic metabolism of anticoagulants; periodic prothrombin time determinations may be required during therapy to determine if dosage adjustments of anti-coagulants are necessary.
Disulfiram: It is recommended that metronidazole not be used concurrently with, or for 2 weeks following disulfiram in alcoholic patients; such use may result in confusion and psychotic reactions because of combined toxicity.
Cimetidine: Hepatic metabolism of metronidazole may be decreased when metronidazole and cimetidine are used concurrently, possibly resulting in delayed elimination and increased serum metronidazole concentrations; monitoring of serum concentrations as a guide to dosage is recommended since dosage adjustment of metronidazole may be necessary during and after cimetidine therapy.
Phenobarbital: Phenobarbital may induce microsomal liver enzymes, increasing metronidazole's metabolism and resulting in a decrease in half-life plasma concentration.
Phenytoin: Metronidazole may impair the clearance of phenytoin, increasing phenytoin's plasma concentration.
Lithium: Concomitant administration may impair clearance of lithium.