General Information

Topamax (topiramate) has been approved as a new antiepileptic drug proven to reduce the frequency of seizures, particularly among patients who are not controlled by other antiepileptic drugs (AEDs). Topamax is indicated as adjunctive therapy for partial onset seizures, the most common seizure type, in adults.

Therapy should be initiated at a low dose of 50 mg per day and gradually increased to an effective dose. The recommended daily dose is 400 mg per day in two divided doses.

A new use for the anti-epileptic drug, Topamax (topiramate) has been approved by the FDA. This new use is as an add-on treatment for pediatric patients (ages 2-16) who experience partial onset seizures. This is the first anti-epileptic drug to be approved for treatment of partial onset seizures in patients as young as two. Partial onset seizures can cause sensory distortion, uncontrolled movements and, in some cases, an altered, trance-like consciousness.

Topamax is available as a tablet and in a capsule formulation that can be opened and sprinkled onto food for easy swallowing. The capsule also can be swallowed whole, offering patients greater flexibility.

Clinical Results

Topamax has been studied in more than 2,000 epilepsy subjects worldwide. Five placebo-controlled, double blind clinical trials with Topamax demonstrated consistent results in reducing the frequency of seizures. In one trial with 181 subjects, seizure frequency was reduced by at least half in 44 percent (vs. 18 percent for placebo) and at least 75 percent in 22 percent of subjects (vs. 18 percent for placebo) taking the recommended 400 mg per day. Once stabilized on Topamax, four percent of subjects were seizure free throughout the trial period; no subjects on placebo were free of seizures during the same trial period. Patients selected for the trial were being treated with traditional AEDs; their average seizure frequency was approximately 11 per month at the time they entered the trial.

Partial onset seizures: In a double-blinded, randomized, placebo-controlled trial of 86 pediatric patients between the ages of two and 16, at 17 clinical sites, Topamax effectively reduced the frequency of partial onset seizures in this population. Pediatric patients who received Topamax as add-on therapy with baseline anti-epileptic drugs (AEDs) over the course of the 16-week trial experienced a 33% reduction in seizures, compared to 11% for placebo and baseline AEDs.

Side Effects

Clinical trials indicate that Topamax is generally well tolerated by subjects and has few clinically significant interactions with traditional AEDs. The most frequently reported side effects were related to the central nervous system, which is common for this class of drugs, such as difficulty concentrating, drowsiness, dizziness and coordination problems. Most side effects were mild to moderate in severity and usually disappeared over time. There was a 1.5 percent incidence of kidney stones; nearly 80 percent of patients experiencing stones continued Topamax therapy.

In the pediatric trial, the most common side effects associated with Topamax as add-on therapy included excessive drowsiness, loss of appetite, fatigue, nervousness, difficulty with concentration/attention, weight decrease, aggressive reaction, and difficulty with memory.