This is an exciting year for antiepileptic drug therapy: three new drugs became available in the United States in 2009, and two others have filed applications for approval with the FDA. The first new drug was Vimpat (lacosamide). It is useful for partial and secondarily generalized seizures. It is chemically related to the amino acid, serine. Vimpat blocks sodium channels (but in a different way from other seizure medicines), and this block reduces brain excitability. Side effects include dizziness, headache, nausea or vomiting, double vision, fatigue, memory or mood problems. Vimpat may affect the internal organs, blood counts or heart rhythm, but these potentially serious side effects are infrequent. Read more about Vimpat.

The next new drug to be released was Banzel (rufinamide). Banzel is approved for add-on treatment of children age 4 and older and adults with the Lennox Gastaut Syndrome (learn more here). This syndrome can include seizure types such as atonic (drop) seizures, tonic (stiffening) seizures, myoclonic (brief jerking) seizures, or staring (absence) seizures, as well as partial seizures. Banzel works on sodium channels in brain cells, in a way to make them less excitable. Common side effects include headache, dizziness, fatigue and sleepiness, double vision and tremor (trembling). Read more about Banzel.

Recently introduced into the US, although available elsewhere for years, is Sabril (vigabatrin). Vigabatrin is a “designer drug,” made to block metabolism of GABA, the brain’s main inhibitory neurotransmitter. Sabril is effective for partial seizures, with or without secondary generalization. It also may be very effective for infantile spasms, a serious type of seizures in young children. Release in the US was delayed because the drug is toxic to the retina of the eye in up to 30% of people who take it long-term. This toxicity can result in permanent loss of peripheral vision. Regular vision testing is recommended for all people on this drug.

Zebinix (eslicarbazepine acetate) has become available in the UK, Germany, Austria and Denmark, as add-on therapy in adults with partial-onset seizures, with or without secondary generalization. It resembles carbamazepine (Tegretol), but may have fewer drug interactions, and perhaps less tendency to lower blood sodium (hyponatremia). Side effects tend to be double vision, dizziness, headache, upset stomach.

Valeant Pharma and Glaxo are submitting a new drug application to the FDA for the novel AED, retigabine. It is the first anti-seizure drug that appears to work by activating potassium channels in brain cells. This has the effect of lowering brain excitability. It has been effective in testing. The most common side effects are dizziness, fatigue, double vision, confusion and tremor.

Several other medicines are in the works: more about those in future columns.

Robert S. Fisher, M.D., Ph.D.
Editor-in-Chief, epilepsy.com