Warfarin--indications, risks and drug interactions.

BACKGROUND Warfarin is a commonly used medication for the prevention and treatment of venous thromboembolism. It can be challenging for both the patient and the prescriber to manage at times. OBJECTIVE To describe the mechanism of action of warfarin, and to discuss the indications for warfarinisation, the risks associated with warfarin use, and some of its drug interactions. DISCUSSION The common indications for warfarinisation are atrial fibrillation, venous thromboembolism and prosthetic heart valves. Contraindications include absolute and relative contraindications, and an individualised risk-benefit analyses is required for each patient. There are many interactions with warfarin, including pharmacokinetic and pharmacodynamic. Pharmacokinetic interactions can be monitored by using International Normalised Ratio levels. Pharmacodynamic interactions require knowledge by the prescriber to predict any interactions with warfarin, and International Normalised Ratio monitoring assists.

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