Published: June 2010

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Warfarin - reports of serious adverse reactions continue

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Prescriber Update 31(2): 16
June 2010

The risk of major bleeding events in patients prescribed a combination of warfarin and aspirin was highlighted in Prescriber Update in August 2009.¹ Despite this ACC continues to receive reports of serious injury in patients receiving warfarin, including cerebrovascular accidents that have resulted in severe disability.

The ACC reports include cases of warfarin being prescribed concomitantly with aspirin, and of warfarin being prescribed with other medicines known to increase the risk of bleeding.

Healthcare professionals are reminded to regularly monitor INRs in patients prescribed warfarin. Patients on warfarin should also be advised to consult with a healthcare professional before taking over-the-counter medicines in addition to warfarin.

This reminder reflects action taken by medicines regulators around the world. Most recently, the Medicines and Healthcare products Regulatory Agency (MHRA) has updated UK prescribing information to give clearer and up-to-date advice, particularly with respect to haemorrhage.² Although no new safety issues were identified by the MHRA, advice was issued to healthcare professionals in an attempt to reduce the risk of harm associated with warfarin use.

References

1. Medsafe. August 2009. Combination anticoagulants - increased bleeding risk. www.medsafe.govt.nz/profs/PUArticles/Combination anticoagulants - increased bleeding risk.htm
2. MHRA. December 2009. Warfarin: changes to product safety information. http://www.mhra.gov.uk/Safetyinformation/Safetywarningsalertsandrecalls/Safetywarningsandmessagesformedicines/index.htm