The Medicines and Healthcare products Regulatory Agency (MHRA) has issued advice to health care professionals and patients pertaining to the safe use of warfarin and other anticoagulants, after clinicians voiced concerns amid the COVID-19 pandemic.
Advice for clinicians:
- The presence of acute illness may magnify the effect of warfarin, requiring a dose reduction; ask users of warfarin or other vitamin K antagonists (VKAs) to inform their GP or health care team if they experience symptoms of or have confirmed COVID-19 infection.
- In patients with suspected or confirmed COVID-19 infection who were taking warfarin or other VKAs, continued monitoring of international normalised ratio is vital to lower the risk of bleeding.
- Both VKAs and direct-acting oral anticoagulants (DOACs) may interact with prescribed antibiotics or antivirals. Refer product information to minimize the risk of interactions.
- When switching from warfarin to a DOAC, discontinue warfarin before initiating DOACs to lower the risk of over-anticoagulation and bleeding.
- Remind patients taking VKAs to cautiously follow the instructions for use for anticoagulant drugs (including the patient information leaflet) and to inform their GP or health care team if they:
- feel unwell with sickness or diarrhoea or experience loss of appetite;
- start any new medicine or supplement;
- make changes to diet, smoking habits, or alcohol intake; or
- are not able to attend their next scheduled blood test for any reason, including feeling unwell.