For more than 30 years, Cynthia Lynch relied on the brand name drug Dilantin to control her epilepsy, but this past spring, she received a generic form of the drug, phenytoin. Within 8 weeks of switching from Dilantin, she suffered "breakthrough seizures," after having been seizure free for a year and a half.
"I had two seizures in one night and I'd never had two seizures in a night, ever," she says. "It was very disturbing."
For most epileptics, seizures caused by abnormal electrical discharges in the brain are a way of life. Controlling them with medicine is critical to allowing patients as normal a life as possible.
But a new a study suggests the common cost-cutting practice pursued by managed care--of substituting generic drugs for brand names--could place epileptic patients in danger if they are switched from brand name Dilantin to a generic.
A study in the journal Neurology shows that among patients switching from Dilantin to a generic medication, 46% were more likely to suffer increased seizures than those on Dilantin. Results show that compared to Dilantin, the generic actually drops the concentration of the drug in the blood by 37%.
"That may be enough for someone whose seizures [are] controlled to no longer have seizure control," explains Dr. Martha Morrell, a neurologist at Columbia Presbyterian Hospital. She says that the drug phenytoin has a narrow therapeutic range, meaning that even slight changes in formulation can dramatically affect the amount of medicine in the blood.
Conversely, patients switching from generic phenytoin to Dilantin can get too much medicine. The study showed 84% of study participants were at risk for toxic effects like blurred vision, dizziness, and unsteadiness because the drug level had increased an average of 102%.
Many specialists and the Epilepsy Foundation are now recommending these drugs not be swapped without doctors orders.
You may not get the same levels and as a result your levels may dip without you knowing it until you have a seizure.
Adding to the problem is that there are three generic versions of Dilantin. Since pharmacies often buy whichever is cheapest, patients could technically get a different generic every time they refill their prescription.
Though this study focused on Dilantin, specialists say other epilepsy drugs, such as Tegretol, are also highly sensitive.
Make sure your doctor checks the "dispense as written" box on the prescription you take to the pharmacist, but your insurance company might not pay for the brand name.
Cynthia Lynch is now being treated at New York University Medical Center in Manhattan.
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