Potential drug interactions with COVID-19 medications

Since the emergence of COVID-19 there have been significant developments in the antiviral and immunomodulatory medications recommended for patients with COVID-19, including Paxlovid (nirmatrelvir/ritonavir), Lagevrio (molnupravir) and Veklury (remdesivir).
Potentially significant drug interactions may occur between these drugs and other medications, including anticoagulants. Broadly speaking:

• Lagevrio – there are no reported significant drug interactions with warfarin or DOACs at this time.
• Paxlovid – there are important interactions with anticoagulants, particularly with DOACs and also with warfarin.
• Veklury – may increase or decrease the anticoagulant effect of warfarin. Such interactions can impact on laboratory monitoring of anticoagulant use and the safe use of anticoagulants.

It is advised that drug interactions are checked if patients are commenced on the above-listed COVID-19 treatments. Refer to the product information sheets, additionally, the following links provide information on potentially significant drug interactions:

• https://covid19-druginteractions.org/checker. This widely used site is administered by the University of Liverpool, UK.
• https://covid19-sciencetable.ca/sciencebrief/nirmatrelvir-ritonavir-paxlovid-what-prescribers-and-pharmacists-need-to-know-3-0/

It is recommended that you consult with a pharmacist as well as the appropriate clinical services if potentially significant drug interactions are identified.
Regards,
Dr Sophia Otto
Clinical Service Director
SA Pathology
www.sapathology.sa.gov.au