From the Orlando Sentinel:

Nagging complaints about some generic drugs are casting doubt on one of medicine's most widely held assumptions: that generics are just as good as brand-name versions, only cheaper.

In some instances people say their blood pressures and heart rates shoot up when they go on generic heart medications. In others, doctors say epilepsy patients are having seizures when they switch and that people are lapsing back into feeling hopeless on generic antidepressants.

No one is suggesting that all the drugs are troublesome. But some doctors, consumer groups and medical organizations say patients need to know generics don't always work as well as brand names. They are pushing the Food and Drug Administration to take a harder look at the drugs.

"The FDA puts the original pills through incredible hurdles to prove safety and effectiveness," said Dr. Ken Kronhaus, a Lake County cardiologist and spokesman for the American Heart Association. "I think they need to bring the same energy to generics."

The FDA says it does.

The government requires generic makers to show that their products deliver the same dose of medicine with equal effectiveness to the original. Independent drug experts say the testing methods are solid.

Paul Doering is a pharmacist and professor at the University of Florida. He said any assertion that generics are inferior is "disingenuous, misleading and false in its entirety."

Much is at stake in the $60 billion-a-year U.S. generic industry.

Generics are used to fill about 65 percent of all prescriptions in the United States, where millions of people rely on them to treat life-threatening illnesses at lower costs. In some cases, people don't have a choice. Their insurers require them to use a generic or pay higher costs out-of-pocket.

Must be 'bioequivalent'

Some people think generic drugs are carbon copies of the brand names, but that's not the case.

To be a generic, a drug must use the same active ingredient as the original. This is the compound that causes the medicinal effect, such as lowering cholesterol or quelling indigestion. But generics don't need to have the same inactive ingredients, such as the liquid containing the drug, or the materials that cause the pill to stick together.

The FDA is adamant that generics are just as effective as brand-name products.

To be approved, the drugs must be shown to be "bioequivalent," or to work the same way in the body as the original. Generic makers test their drugs by giving them to healthy volunteers and tracking drug levels in their blood over time. The generic must have results similar to the original -- not identical, but very close.

"The FDA has no cases where generic drugs have been shown to not perform as expected," spokeswoman Sandy Walsh wrote in an e-mail. "Health professionals and consumers can be assured that FDA-approved generic drugs have met rigid standards."

2 generics raise questions

But some wonder whether current testing might overlook subtle differences in how the drugs perform. The variations may not affect most patients, but some might have a resurgence in symptoms or side effects when they switch to a generic.

Two of the medications that have caught doctors' attention are generic versions of the antidepressant Wellbutrin and the brand drug Toprol, which is widely prescribed for chest pain, rhythm problems, high blood pressure and other cardiovascular conditions. The generic for Toprol is called metoprolol.

"I've had a lot more people complaining of nausea, dizziness and headaches," Kronhaus said. "Many have had less effectiveness; their heart rates and blood pressures are less controlled on the generic."

Walsh said the FDA is monitoring the generic versions of Toprol, as it does with all drugs, and will evaluate complaints as necessary. The FDA already re-examined the generic Wellbutrin -- sold under the name Budeprion -- and found that it is "a safe and effective choice for consumers in treating depression," Walsh said.

Of the millions of prescriptions dispensed for the generic, the FDA had only 78 formal complaints about its effectiveness at the time of the review.

'Significant differences'

In still another twist, some doctors say patients have problems when they use generics made by different manufacturers from one month to the next. Pharmacies often buy from a variety of makers in an effort to get the best deal.

Each generic subjects patients to small shifts, said Dr. James Hennessey, an endocrinologist and associate professor of medicine at Harvard University.

Some of his patients have struggled with generic versions of Synthroid, a common medicine for thyroid conditions. Though they might do fine on any single generic, their thyroid levels go askew when they get switched to another.

Doctors also say they've seen problems with anti-seizure medications, which work at very precise levels in the bloodstream. The Epilepsy Foundation even asked the FDA to consider special labeling on generic versions of the drugs but was turned down.

Walsh said there is no scientific evidence to support the need for warnings on the drugs. But doctors say some patients are having seizures when they switch.

"One generic may fit within the lower range of bioequivalence that is acceptable, and another may be closer to the upper range," said Dr. Alan B. Ettinger from the Long Island Jewish Medical Center and a spokesman for the foundation. "This can translate into great variability in the levels of the drug in the bloodstream."