Counselling+metronidazole+and+warfarin

=Drug interaction: Warfarin and Metronidazole=

//Interaction Severity: Moderate

Documentation: Good

The generic Warfarin sodium has its effect markedly increased by Metronidazole

Precautions to take: 1. Use combination with caution. 2. Monitor INR.

Drug Interaction Details: The anticoagulant effects of warfarin are markedly increased by metronidazole. Bleeding (haemorrhage and ecchymoses) has been reported. Metronidazole preferentially inhibits the metabolism of (S)-warfarin, the pharmacologically more potent isomer. Other coumarin anticoagulants may interact similarly. Avoid the combination unless benefit outweighs the risk. If the combination is used, monitor INR/PT and decrease the warfarin dose as necessary.

References:

Yacobi A, Lai CM, Levy G. Pharmacokinetic and pharmacodynamic studies of acute interaction between warfarin enantiomers and metronidazole in rats. J Pharmacol Exp Ther 1984; 231: (Pt 1/Oct): 72-9. Kazmier FJ. A significant interaction between metronidazole and warfarin. Mayo Clin Proc 1976; 51: (Pt 12/Dec): 782-4.//