Generic drugs often differ from brand name drugs in their safety labeling despite standards mandated by the US Food and Drug Administration (FDA), according to a new report.
"Physicians should be aware of such differences and regulators should consider new strategies for harmonizing bioequivalent labels," Jon Duke, MD, from the Regenstrief Institute and Indiana University School of Medicine, both in Indianapolis, and colleagues write.
For years, insurance companies have been working hard to get people to switch to generics. Medicare, too, has been coaxing its clients toward these cheaper drugs. And those efforts are succeeding: Americans fill 1 billion prescriptions for generics yearly and count on them to work as well as brand-name medications. But at the People's Pharmacy, we've worried about generics for years now. At our Web site, we've heard from hundreds of people who've had difficulties with some of these substitutes. They've told us, for example, that their normally manageable blood pressure spiked when they switched to a generic drug, or that the pain of bone cancer was made bearable by a prescription painkiller--but became excruciating when they had to rely on a generic. Or that their depression returned with a vengeance when they were moved to a generic antidepressant--as Smith-West experienced.
There's little research comparing generics with their brand-name counterparts. But a few studies indicate problems with specific types of drugs. In a 2000 survey of 130 cardiologists, for instance, the doctors reported 60 patients who'd gotten into trouble on a generic version of a drug meant to prevent cardiac arrhythmia, a potentially lethal heart rhythm disturbance (three of the patients died). And in Minnesota a few years ago, there was a statewide "experiment" with the anti-seizure drug Dilantin and its generic, phenytoin. In the late 1990s, the state began requiring pharmacists to use generic phenytoin to fill Dilantin prescriptions whenever possible. Neurologists in the state began to see patients who'd done well for years on Dilantin, but who suddenly were having more frequent and severe seizures. When researchers at the University of Minnesota did blood tests, they discovered that blood levels of the active ingredient were 30% lower in people taking a generic than in patients on Dilantin. The finding prompted Minnesota to exempt Dilantin from its push to encourage generics.Finally, thyroid specialists say that using generics can be tricky for a patient on thyroid replacement hormone. "Each of the generics is fine--but you shouldn't switch from one to the other," says Jeffrey R. Garber, MD, author of The Harvard Medical School Guide to Overcoming Thyroid Problems and vice president of the American Association of Clinical Endocrinologists.
Unfortunately, Garber says, if a prescription doesn't say something like do not substitute, the pharmacist can fill it with any generic at all, jumping from one to the other depending on what's in stock. "That's the way the system works," he says.