Generic drugs are cheaper than brand-name pharmaceuticals, and insurance companies and pharmacies -- sometimes the patients too -- love them for that reason. But consumers may be surprised to learn they are not necessarily created equal, and are not required to be, strictly speaking, under Federal Drug Administration regulations.

Variations in the formulations of medications can cause difficulties for some patients -- for example, people with epilepsy.

As explained by epilepsy specialist Dr. Anto Bagic at the University of Pittsburgh, the FDA mandates only a set of factors defining the pharmaceutical equivalence of a brand drug and its generic formulations. The FDA requires the same amount and purity of active ingredients in both.

Chief of the Epilepsy Division of the University of Pittsburgh Medical Center and director of the University of Pittsburgh Comprehensive Epilepsy Center, Dr. Bagic said that, technically speaking, for a generic product to be considered equivalent it has to have a similar measurements of the medication's distribution in the body and the medication's rate of reaching its greatest concentration in the bloodstream.

"Since antiseizure medications must be maintained at a certain therapeutic level in a patient's bloodstream, a switch from a brand-name to a generic drug or between generic versions can have various undesired results," he said.

"When a generic is approved there is an FDA process they go through, but they are never compared with each other," Dr. Bagic said. The therapeutic effect may not be equivalent.

Unfortunately that is something that what Dr. Bagic called a small percentage of patients with seizure disorder (epilepsy) have found out the hard way.

Take the case of 11-year-old Vincent Mroz, of Forest Hills, who was diagnosed with a seizure disorder back in November 1999. According to his mother, Amy Mroz, he did fine on a brand-name drug (generic name: levetiracetam) until late 2006, when the manufacturer reformulated it, taking out some of the cornstarch filler and making a smaller caplet.

"That was the beginning of him [having] repeated seizures and most of the negative side effects [including severe anxiety] of the medication," Mrs. Mroz said in an e-mail interview Monday. "One time he even wound up having a seizure where he fell straight back and split his head open. Poor kid has an assortment of scars on his head."

Vinnie, as his family calls him, ended up in a hospital for a week to start the process of getting him straightened out both chemically and mentally, for he was both anxious and deeply depressed. But it took several months to get him weaned from the brand-name levetiracetam and then onto another brand-name drug (generic name: lamotrigine).

"Then in November 2008 his [lamotrigine] was changed to a generic formula. ... The doctor said because of insurance, let's try the generic," Ms. Mroz said.

Vinnie started having seizures again and underwent multiple testing of drug levels in his blood.

"Since then, the doctor upped his dosage. He seemed fine for a few weeks," Ms. Mroz said. "The pharmacy then changed the generic suppliers. Vinnie only wound up taking one of the other generic pills and our pharmacy changed the tablets back to the generic type that his body was used to.

"However, over the past week or so, he has been having little seizures at school, and he is back for more blood level [tests] after school today. ...

"Thankfully, he has been able to be controlled by one medication," his mother added. "Some of his acquaintances that we have met through the Epilepsy Foundation need two or more medications -- which make it so much harder."

Dr. Bagic said he has seen the problem for the past few decades, as older antiepileptic medications became generic.

"What makes this situation more pronounced and complex is the fact that last year several antiepileptic medications became available in generic forms, so basically a large number of patients became exposed to this situation practically simultaneously. ...

"Additionally, there are many manufacturers of generics. For example, I just heard that Keppra (levetiracetam) is being made by 20 different manufacturers. This introduces additional complexity since the continuity of supply may not be ensured. For example, one of my patients brought a newly filled bottle containing three different generics of her antiepileptic medication."

Dr. Bagic himself has a patient who had been stable for more than a year and then experienced a seizure three or four weeks after she switched to a generic medication.

But before a doctor can blame the generic, Dr. Bagic said, other issues must be considered: "Has she been taking her medication regularly? Has something else changed? Was she sleep-deprived? Did she perhaps have some alcohol the night before? Did she perhaps use other medication that might interact with her antiepileptic medication, etc."

So what should the patients with seizure disorder (epilepsy) do when trying to decide whether to go with one of the generic options?

"Fortunately, most patients have no problems associated with the switch," Dr. Bagic said. "But, here's how I approach the situation with my patients: If a patient is seizure-free I am very sensitive and basically discourage switching unless absolutely necessary due to insurance and financial constraints. Then, I explain that breakthrough seizures may in fact happen.

"We all have to realize that controlling epileptic seizures means maintaining a very fragile balance of many factors since epilepsy is a condition with a narrow therapeutic range. So once you reach that working balance and seizures are controlled, obviously you don't want to change anything. I am particularly careful with those with a history of very prolonged seizures known as status epilepticus, those who are driving or pregnant.

"If a person has to go generic, then I have no choice but to work with them. It is critical to counsel patients comprehensively regarding the necessity of taking medications as prescribed, keeping their sleep regular, eating regularly, and avoiding alcohol and drugs."

He takes a different tack if a patient has ongoing seizures.

"Rarely, trying generics gives you an opportunity to work on maybe improving the situation in those whose seizures are uncontrolled," he said. "The problem is switching may happen without me knowing or the patient knowing about it. Thus, as physicians, we have to do more in terms of involving patients and empowering them to become a part of the therapeutic process. It's not like treating a sore throat."

Dr. Bagic added that patients should also involve their pharmacist and document the manufacturer and lot number of their generic medication. Then, unwanted results could be reported to the FDA.

The Epilepsy Foundation Western/Central PA can be reached at 412-322-5880 or 1-800-361-5885 or at www.efwp.org.