Users of Generic Blood Pressure Drugs May Experience More Adverse Events

Drug-related adverse events increased significantly following the commercialization of 3 blood pressure medications, according to the findings of a recent study.

Using interrupted time series analysis, the researchers examined the incidence of adverse drug events associated with losartan, valsartan, and candesartan among a cohort of 136,177 individuals enrolled in the Quebec Integrated Chronic Disease Surveillance System. The researchers defined adverse events as emergency room consultations and hospitalizations. In addition, they compared the rates of adverse events from 24 months before generic commercialization to 12 months after commercialization.
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Overall, the researchers calculated a monthly mean rate of 100 adverse events for 1000 angiotensin II receptor blocker users before and after commercialization.

However, the rates of adverse events during the month of commercialization increased among generic users to 8% for losartan, 11.7% for valsartan, and 14% for candesartan. The researchers observed increases in adverse events among users of the generic losartan and decreases among users of brand-name losartan within 1 year after commercialization. These findings were similar in sensitivity analyses.

“Among generic users, immediate or delayed differences in adverse events rates were observed right after generic commercialization for 3 antihypertensive drugs. Rates of adverse events remained higher for generic users,” the researchers concluded. “Increases were more pronounced for generic candesartan, which is the studied product with the largest difference in comparative bioavailability. Risk and survival analysis studies controlling for several potential confounding factors are required to better characterize generic substitution.”

—Melissa Weiss

Reference:

Leclerc J, Blais C, Rochette L, Hamel D, Guénette L, Poirier P. Impact of the commercialization of three generic angiotensin II receptor blockers on adverse events in Quebec, Canada: a population-based time series analysis [published online October 3, 2017]. Circulation. https://doi.org/10.1161/CIRCOUTCOMES.117.003891.