Viatris Pty Ltd has advised the Therapeutic Goods Administration (TGA) of shortages of several warfarin products due to manufacturing issues. The shortages currently affect Coumadin (warfarin sodium) 2 mg and 5 mg tablets.
Warfarin is an anticoagulant used to prevent blood from excessive clotting or forming harmful clots for patients at risk of heart attack and stroke. While the two brands of warfarin marketed in Australia (Coumadin and Marevan) are both available in various strengths, they are not bioequivalent and should not be interchanged unless under medical supervision.
The shortage of the Coumadin 5 mg tablets was expected to continue until 31 July 2023. The shortage of the Coumadin 2 mg tablets was expected to continue until 14 April 2023. To minimise disruption to patients, Viatris is working to increase supply of Coumadin 1 mg and 2 mg tablets to allow patients to maintain their prescribed dose using a combination of the lower strengths available, in consultation with a health professional.
The TGA is working closely with Viatris and other stakeholders to minimise the shortage impact. We have made a Serious Scarcity Substitution Instrument (SSSI) to assist patients in accessing warfarin from their pharmacist without delay or interruption to treatment. The SSSI allows a pharmacist to offer patients a lower strength of Coumadin tablet to achieve the prescribed dose, if the 5 mg tablet is unavailable, without prior approval from the prescriber.
To ensure access to the limited stock is maintained as widely as possible, the TGA urges pharmacists and consumers not to stockpile Coumadin or Marevan.
The latest information about the shortages and the expected return to supply dates is available on the Medicine Shortage Reports Database on the TGA website.
The TGA is also aware of concerns raised about the new packaging of the warfarin product range (blue bottle presentation). We are working closely with Viatris to further differentiate the different strengths of each product label without disrupting supply.
Information for consumers
Consumers who are having difficulty accessing warfarin products should consult their pharmacist or GP for advice.
Viatris holds limited emergency stock of Coumadin that can be shipped directly to pharmacies in urgent cases. Consumers can talk to their pharmacist and, if needed, ask them to call Viatris on 1800 314 527 to enquire about access.
Information for health professionals
Due to the narrow therapeutic index of warfarin and the lack of data on bioequivalence between Coumadin and Marevan, these products are not considered interchangeable. If substituting or switching is unavoidable, close monitoring with frequent INR testing is recommended.
Viatris holds limited emergency stock of Coumadin that can be shipped directly to pharmacies in urgent cases. Pharmacists can call Viatris on 1800 314 527 to enquire about access.
Pharmacists should be alert to the Serious Scarcity Substitution Instrument (SSSI) allowing them to substitute strengths in certain scenarios.