This has been an ongoing issue for people with epilepsy. In 2006 the American Academy of Neurology recommended that pharmacists not substitute generic versions of antiseizure drugs for people with epilepsy without their consent and their doctor’s. The concerns stem from anecdotal reports of treatment failures, such as an increase in epileptic seizures, after patients switched from a branded to a generic medication. Observational studies involving epilepsy patients who switched to generic versions reported higher switchback rates to branded drugs than for other classes of drugs, and more epilepsy-related doctor visits, hospitalizations, and prescription drug use.
Those studies, however, contradict the findings of randomized controlled trials. For example, a 2010 meta-analysis conducted by Kesselheim and his colleagues comparing brand-name antiepileptic drugs with generics found no difference in seizure control in seven such trials. But the trials were small and had other limitations. Another 2010 study reported increased seizures around the time the prescription was refilled—whether it involved a switch from brand to generic, generic to generic, or even a refill of the same medication. This might be due to a brief lapse in treatment during the refilling process, or to slight variations between different drugs or different lots of the same drug produced by the same manufacturer.
Cardiovascular drugs were investigated in a 2008 meta-analysis of 38 randomized controlled trials, also conducted by Kesselheim and his colleagues. They found no evidence that brand-name heart drugs worked any better than their generic versions. The analysis included NTI drugs such as antiarrythmics and the blood thinner warfarin (Coumadin), as well as drugs to lower blood pressure, cholesterol-lowering statins, and the antiplatelet drugs aspirin and clopidogrel (Plavix).
For NTI drugs, particularly those to treat epilepsy, our medical consultants recommend staying on a generic made by one manufacturer to avoid slight variations that may occur with different manufacturers. Talk with your pharmacist to ensure that he or she can provide that consistency month-to-month, or at least tell you if the pharmacy switches its generic supplier. If you do switch to a different generic or from a brand to a generic, your doctor may want to monitor your response more closely during the transition period.