Paul S. Mueller, MD, MPH, FACP reviewing Romley JA et al. 2015 Dec 7.
Many adverse drug events are attributable to warfarin and to oral antidiabetes drugs. Whether warfarin potentiates the hypoglycemic effects of antidiabetes drugs — and in particular, sulfonylureas — is unclear. In this retrospective cohort study, researchers determined whether warfarin use was associated with excess risk for serious hypoglycemic events in 470,000 Medicare beneficiaries with type 2 diabetes who were treated with oral sulfonylureas (glipizide or glimepiride) from 2006 through 2011.
About 15% of sulfonylurea recipients filled prescriptions for warfarin. In multivariable analysis, emergency department (ED) visits or hospital admissions for hypoglycemia were 22% more likely during concurrent warfarin and sulfonylurea use than during use of sulfonylurea alone; this risk was higher during the initial months of concurrent warfarin and sulfonylurea use (odds ratio, 2.47). ED visits or hospital admissions for fall-related fractures were 47% more likely, and altered mental status was 22% more likely during concurrent use.
In this study, ED visits or hospital admissions for hypoglycemia and related adverse events were more common with concurrent warfarin and glipizide or glimepiride than with a sulfonylurea alone. Because both warfarin and sulfonylureas are metabolized by CYP2C9, the authors speculate that warfarin alters sulfonylurea metabolism, thereby potentiating its hypoglycemic effects. This study has several limitations: Drug use was not measured directly; confounding due to unmeasured variables related to warfarin and risk for hypoglycemia is possible; and the results might not be generalizable to younger populations.
Romley JA et al. Association between use of warfarin with common sulfonylureas and serious hypoglycemic events: Retrospective cohort analysis. ; :h6223. (http://dx.doi.org/10.1136/bmj.h6223 )