Study validates switch to generic anticonvulsants

Switching from branded to generic drugs for epilepsy did not cause increased incidents or utilization changes among patients, according to new study results.

Brian Solow, MD, vice president and senior medical director for pharmacy benefit manager Prescription Solutions, and Sara C. Erickson, PharmD, senior outcomes researcher for the company, presented the results of the anti-epilepsy drug research in May at the annual meeting of the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) in Atlanta, Ga.

Solow, Erickson, and other researchers reviewed insurance claims histories for 2,139 epileptic patients and found that patients whose doctors switched them to generic drugs from the branded versions of lamotrigine or divalproex (used as anticonvulsants) did not have increased hospitalizations and incidences.

The story was different for patients who switched from the branded version of phenytoin to generic anti-epileptic drugs (AEDs); they experienced more drug discontinuations and changes, as well as therapy augmentations. Still, the switch to generic phenytoin did not cause an increase in emergency room visits and hospitalizations. "The phenytoin group was a very different group from the other two. It is an older epileptic drug, and the patients tend to be older patients with a higher morbidity rate," Erickson said.

Further research on brand-to-generic switching of AEDs could focus on patients' medical records, to determine whether there were adverse events associated with switching, Solow said. Meanwhile, "We are going to continue to look at the retrospective data and ... present this for publication."