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.


CONCLUSIONS
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.
Tadros
Rami
R
Department of Clinical Pharmacology, The Royal Adelaide Hospital, South Australia. rami.tadros@health.sa.gov.au
Shakib
Sepehr
S
D000925:Anticoagulants / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000209:etiology; D003577:Cytochrome P-450 Enzyme System; D004347:Drug Interactions; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D006801:Humans; D019934:International Normalized Ratio; D012307:Risk Factors; D054556:Venous Thromboembolism / Q000150:complications / Q000188:drug therapy*; D014812:Vitamin K / Q000032:analysis / Q000037:antagonists & inhibitors; D014859:Warfarin / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*
D000925:Anticoagulants; D014812:Vitamin K; D014859:Warfarin; D003577:Cytochrome P-450 Enzyme System