Coumadin vs. Generic Warfarin: The Jury's Out
By Barbara A. Biedrzycki, RN, MSN, AOCN, CRNP
Controversy exists regarding the bioequivalence of generic warfarin and the innovator product, Coumadin, by DuPont Pharma in Wilmington, DE. Originally patented by DuPont Pharma as Coumadin, warfarin sodium became commercially available in 1997 through Barr Laboratories in Pomona, NY, as a generic product.
Pharmacists Steven R. Benson and Kyle Vance-Bryan of Value Rx, a pharmacy benefits management company in Plymouth, NM, have concerns that the results of the independently conducted clinical trial allegedly proving Coumadin and the generic product are interchangeable are available only in abstract form and not in a peer-reviewed journal. Benson and Vance-Bryan said in the American Journal of Health-Systems Pharmacists, "We reviewed the abstract and have various concerns with the study's design and authors' conclusions."1
Awaiting evidence that Barr Laboratories' guidelines are as strict as DuPont Pharma and the published therapeutic equivalence data, Benson and Vance-Bryan support Coumadin as their company's only warfarin product. Usually, we expect a significant cost savings when we chose a generic drug, but that is not so in the case of warfarin.
Pharmacist Stuart T. Haines of the University of Maryland Medical Systems in Baltimore notes a modest difference in the cost of generic warfarin; wholesale prices are only about 14% lower than Coumadin. However, he expects prices to drop because the generic product will stir price competition.2
Does Cost Outweigh Savings?
Based on those commentaries, it appears more evidence is needed before a research-based conclusion can be made regarding the bioequivalence of Coumadin and the generic product. Some feel the cost of the additional monitoring that may be needed to manage patients on the generic form of warfarin outweighs the modest cost savings.
Another concern is whether Barr Laboratories will be able to match or exceed the extensive free patient and health care provider resources that DuPont Pharma provides. Also, some wonder whether the continual research and development of such an important medication will be sustained. In other words, the jury's still out.
References
1. Benson S, Vance-Bryan, K. In favor of Coumadin over generic warfarin. Am J Health-Sys Pharm 1998; 55:727-729.
2. Haines S. Reflections on generic coumadin. Am J Health-Sys Pharm 1998;55:727-729.
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