Don't switch from brand-name Dilantin (search) to a generic version of the antiseizure drug — or from generic to brand name, epilepsy specialists warn.
The warning comes after epilepsy patients at MINCEP Epilepsy Care, in Minneapolis, Minn., suddenly began having severe seizures. (search) The patients' seizures previously had been kept under control with Dilantin treatment.
What happened? An investigation by Ilo E. Leppik, MD, MINCEP research director and professor of pharmacy at the University of Minnesota, found a clue. A change in State of Minnesota health plans required the use of generic drugs instead of brand-name drugs. Without notifying their doctors, the health plans switched the patients from brand-name Dilantin to a generic version.
"We didn't even know they had done this until we saw these developmentally delayed kids and adults coming into the clinic or emergency room with seizures," Leppik tells WebMD. "It turned out all these kids had been switched from brand-name Dilantin to generic."
Because they had a carefully kept record of the patient's Dilantin blood levels, the researchers were able to compare the effects of the switch. Sure enough, the patients had much lower blood levels of the drug after switching to the generic version. Once they switched back, drug levels increased into a range that controls seizures.
The findings appear in the October issue of Neurology.
Dilantin: A Tricky Epilepsy Drug
Dilantin, made by Parke-Davis, is the brand name for phenytoin (search). For more than 50 years, it's helped people with epilepsy keep their seizures under control. Doctors use it often — but it's one of the trickiest drugs around, says Gregory L. Barkley, MD, chair of the Epilepsy Foundation's professional advisory board and clinical vice chair of neurology at Detroit's Henry Ford Hospital.
"The issue with phenytoin is it is the single most difficult anticonvulsant drug to use because it has very different metabolism than most medicines," Barkley tells WebMD. "Small changes in dose result in wild swings in metabolism."
The small differences between Dilantin and generic phenytoin can have big clinical effects.
"Given the nature of the thin margin between too much and too little phenytoin, I am not surprised switching from one brand to the other makes problems," Barkley says.
Generic Epilepsy Drug Not Bad, Just Different
Leppik says that for 15 years, one of his patients kept her epilepsy seizures under control with Dilantin. That suddenly changed.
"This year, she shows up in my clinic with two seizures," he says. "She lost her driver's license, and her blood levels of Dilantin were low. She said she'd been taking her medicine same as always. So I asked her, 'Do your pills look different?' She said, 'Yes, but my pharmacist said it was the same thing, so don't worry.' We got her back on brand-name Dilantin, and now she is doing fine."
Leppik and Barkley stress that brand-name Dilantin isn't necessarily better than generic versions of the drug. It's just different — and this difference may be important.
"My recommendation is if you're on Dilantin, don't' switch. And if you're on generic phenytoin don't switch," Leppik says. "Either way you can get into trouble. The worst is switching back and forth."
Barkley says that while the cost of Dilantin is only a few cents a pill more than generic versions, most of his patients taking phenytoin are on generic versions of the drug.
"In most cases, generic drugs are a good deal for the consumer," he notes. "It is the best thing for keeping drug costs low."
In the case of switching patients from Dilantin to generic phenytoin, however, any savings could be wiped out by a single trip to the emergency room.
"Switching from Dilantin to a generic version may be penny wise and pound foolish," Barkley says.
Leppik advises people taking either Dilantin or generic phenytoin to pay attention when they're at the drug store.
"The message here is to look carefully at your pills when you go to the pharmacy," he says. "If you are taking Dilantin brand, be sure to continue. If you're getting a generic brand of phenytoin, be sure to get same-looking generics."
Meanwhile, Leppik and colleagues took their findings to the Minnesota state health authorities. They changed the rule requiring a switch to generic Dilantin.
SOURCES: Burkhardt, R.T. Neurology, October 2004; vol 63: pp 1494-1496. Ilo E. Leppik, MD, research director, MINCEP Epilepsy Care; and professor of pharmacy, University of Minnesota, Minneapolis. Gregory L. Barkley, MD, chair, Epilepsy Foundation's professional advisory board; and clinical vice chair of neurology, Henry Ford Hospital, Detroit.