Switching Between Generic AEDs Not Linked to Hospital Visits for Seizure

Switching between generic versions of the same antiepileptic drug made by different manufacturers does not appear to change the risk of seizure-related events in patients with epilepsy, according to a population-based, case–crossover study of generic antiepileptic drug users published online ahead of print September 28 in Neurology. Delays and complications of the medication refilling process might increase a patient’s risk for a seizure, said Aaron Kesselheim, MD, JD, MPH, Associate Professor of Medicine at Harvard Medical School in Boston, and colleagues.

Aaron Kesselheim, MD, JD, MPH

“These results add to the growing literature supporting the routine use of interchangeable generic [antiepileptic drugs] among patients with seizure disorders,” he added.

Although previous observational studies have demonstrated increased seizure activity following a switch from brand name to generic antiepileptic drugs, several recent randomized trials have found no
link between generic drug switching and seizure risk, said Dr. Kesselheim.

Investigators identified 59,344 patients with at least one refill of a prescription from the same manufacturer and 5,200 patients who switched from one generic to another from 2000 to 2010 in the Medicaid Analytic eXtract database and from 2005 to 2013 in a commercial health insurance database. Participants acted as their own controls in the study’s comparison of the effects of a refill or a refill with a switch in manufacturer on seizure-related events (ie, a seizure requiring an emergency department visit or hospitalization) during a hazard period, defined as days 2–36 preceding a seizure-related event, and a control period, defined as days 51–85 preceding the seizure-related event.

Overall, generic antiepileptic refilling of the same medication from the same manufacturer was associated with an 8% increase in the odds of having a seizure-related event. When the refill involved a switch to the same generic drug made by a different manufacturer, the odds of a seizure-related event rose by 9%. When the refill involved a change in the shape or color of the pill, the odds increased by 11% but did not increase when the switch was made to a pill with the same color and shape. The increased odds of seizure-related events became nonsignificant when the researchers adjusted these comparisons for the process of refilling, which “is often not straightforward,” said Dr. Kesselheim. “Patients have expressed frustration with delays and other complicating factors relating to refilling.… Greater work to enhance the refilling process, and to determine whether mail order pharmacies successfully improve outcomes on this point, is necessary.”

The study was not supported by any specific targeted funding. The investigators received support from various foundations and from programs within Harvard University and grants from the Agency for Healthcare Research and Quality and the FDA.The investigators also disclosed acting in a research support role for or receiving financial compensation from several pharmaceutical companies and other organizations.

—Jessica Craig

Suggested Reading

Kesselheim AS, Bykov K, Gagne JJ, et al. Switching generic antiepileptic drug manufacturer not linked to seizures: a case-crossover study. Neurology. 2016 Sep 28 [Epub ahead of print].

Krauss GL, Privitera M. More data on the safety of generic substitution: yes, the blue tablet is OK? Neurology. 2016 Sep 28 [Epub ahead of print].