National Stroke Foundation

Topamax (topiramate)

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.

Approval Status:

Approved January 1997

Specific Treatments:

partial onset seizures

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.

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.

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.

Additional Information

Approximately 30 percent of people with epilepsy in the United States--at least 650,000 patients--continue to experience seizures despite treatment with currently available medications.

Epilepsy is a chronic condition characterized by recurrent, unprovoked seizures, or electrical disturbances in the brain that can alter a patient’s consciousness, movement or behaviors. Seizures are characterized as either partial or generalized, depending on where they originate in the brain.