Felbamate


Brief Overview:

Felbamate (Felbatol®) is a broad-spectrum anti-seizure drug which is effective in the treatment of many types of epilepsy, though it is unclear whether or not it is effective in the treatment of infantile spasms. Although quite effective in general, felbamate is seldom used because of several very rare but very serious potential side effects (discussed below). Among anti-seizure drugs, felbamate possesses a unique mechanism of action with its influence at a brain cell receptor called NMDA. Felbamate is supplied in tablets and a liquid. 

Dosage:

A typical dosage of felbamate ranges from 40 to 100 mg/kg/day, divided in 2 to 3 doses each day. It should be started at a low dose, and dosage should be steadily increased over several weeks to a couple months. Felbamate interacts with many medications including several anti-seizure drugs. Accordingly, the dosage of felbamate or other drugs taken simultaneously may need to be adjusted. 

Side Effects:

Felbamate is notorious for very rarely causing (1) severe liver injury (hepatotoxicity), and (2) a severe blood disorder called aplastic anemia. Periodic blood tests are advised to screen for these possible side effects. Although treatment for these side effects is available, both of these side effects are very dangerous and potentially life-threatening. Children appear to be at substantially lower risk of aplastic anemia (no reports under the age of 13 years, risk in adults is approximately 1 in 8000 exposures, and the risk in the general population is 1 per 250,000 per year), and the risk of fatal liver injury appears to be lower (approximately 1 in 30,000 exposures) than that observed with valproic acid. This explains in part why felbamate is rarely used by adult practitioners and more commonly prescribed among pediatric practitioners. Having said this, most children who take felbamate do not suffer any significant side effects, and the most consistently observed effects are a reduction in appetite, weight loss, and less frequently, insomnia. In many cases, the potential benefits of felbamate (namely seizure-freedom) far outweigh the potential risks of this medication. As with all medications, a discussion of the risks and benefits of therapy is required. You should of course contact your physician immediately in the event that any of these side effects are observed or suspected. Symptoms of aplastic anemia are highly non-specific and include fatigue and easy bruising/bleeding. Similarly, symptoms of liver injury are highly non-specific and include fatigue, nausea, and vomiting (which are unfortunately very common medication side effects among patients without any liver problems). Blood tests to monitor blood cell counts and liver function are often recommended because the symptoms of liver injury and aplastic anemia are difficult to detect.


Disclaimer:

This medication should be administered only under the direct supervision of a physician.

Although efforts are made to keep this website correct and up-to-date, we urge caution in interpreting the information you find here. This is in no way a substitute for the advice and care of a pediatric neurologist. Please view the terms of use.


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