The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.
Letter to the Editor
Although a comprehensive guide to managing warfarin, the article in the April 2015 issue (Aust Prescr 2015;38:44-8) did not mention the problem of brand confusion with warfarin. Transition of care, such as hospital admission, is a time when warfarin management may be compromised. In Australia we have two brands − Coumadin and Marevan. Both are manufactured by Aspen Pharmaceuticals, and are available in different strengths and tablet colours. Recently reported incidents involving warfarin brand confusion at our hospital resulted in dose omissions due to Marevan not being available on the ward and inadvertent switching from Marevan to Coumadin. Although no patient harm resulted, time was spent in sourcing the ‘right’ brand and managing the incidents.
The Pharmaceutical Benefits Scheme notes that the brands have not been shown to be bioequivalent and should not be interchanged.1 However, a systematic review comparing the bioequivalence of six international warfarin brands found that switching brands was relatively safe.2 In 44 years of reporting adverse drug reactions in Australia, only three reports, all from 1977, implicate brand switching.3
The manufacturer has previously been approached to phase out one brand, with a recommendation that Coumadin be primarily used.4 We call for either bioequivalence testing of Coumadin and Marevan by the manufacturer or, in the interests of medication safety, for only one brand of warfarin to be available.
Senior medication safety pharmacist
Honorary clinical pharmacologist
- Pharmaceutical Benefits Scheme. Warfarin. Canberra: Australian Government Department of Health; 2015. www.pbs.gov.au/medicine/item/2843P [cited 2015 Sep 7]
- Dentali F, Donadini MP, Clark N, Crowther MA, Garcia D, Hylek E. Brand name versus generic warfarin: a systematic review of the literature. Pharmacotherapy 2011;31:386-93.
- Therapeutic Goods Administration. Database of Adverse Event Notifications (DAEN). Canberra: Department of Health; 2013. www.tga.gov.au/database‑adverse‑event notifications‑daen [cited 2015 Sep 7]
- Dooley M. Recommendations for warfarin in Victorian public hospitals. Aust Prescr 2003;26:27-9.