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Warfarin

Starting treatment
Indications
Dosing and monitoring
Complications
Follow-up
Follow-up

Advise your patient that many drugs and foods interact with warfarin and patients should check that any new medication they take is safe b  

Note:

Anticoagulation is potentiated by b
  • antibiotics and antifungals: co-trimoxazole, erythromycin, fluconazole, isoniazid, metronidazole, miconazole
  • cardiac drugs: amiodarone, statins, clofibrate, propafenone, propranolol, sulfinpyrazone
  • analgesics: piroxicam, phenylbutazone, paracetamol
  • alcohol (only with concomitant liver disease)
  • cimetidine and omeprazole
Anticoagulation is inhibited by b
  • antibiotics and antifungals: griseofulvin, rifampicin, nafcillin
  • CNS drugs: barbiturates, carbemazepine, chlordiazepoxide
  • cholestyramine
  • sucralfate
  • foods and enteral feeds high in vitamin K, and large amounts of avocado

Expiry date: May 2003
Levels of Evidence used in grading these guides

With thanks to Drs. David Keeling, John Reynolds, David Sackett, Sharon Straus and Alan Townsend 
 for use of their anticoagulation guide on which this one is based.

Author   CM   Ball
Reviewer   A   Gallus
CAT Writer   CM   Ball