Topiramate (brand name Topamax) is an anticonvulsant (antiepilepsy) drug. It was originally produced by Ortho-McNeil Neurologics and Noramco, Inc., both divisions of the Johnson & Johnson Corporation. This medication was discovered in 1979 by Bruce E. Maryanoff and Joseph F. Gardocki during their research work at McNeil Pharmaceutical. Generic versions are available in Canada and these were approved by the Food and Drug Administration (FDA) in September 2006. Mylan Pharmaceuticals was recently granted final approval for generic topiramate 25, 100, and 200 mg tablets and sprinkle capsules by the FDA for sale in the United States. 50 mg tablets were granted tentative approval. The last patent for topiramate in the U.S. was for pediatric use; this patent expired on February 28, 2009.

Topiramate is used to treat epilepsy in children and adults, and it was originally used as an anticonvulsant. In children, it is indicated for the treatment of Lennox-Gastaut syndrome, a disorder that causes seizures and developmental delay. It is also Food and Drug Administration (FDA) approved for, and most frequently prescribed for, the prevention of migraines. Psychiatrists have used topiramate to treat bipolar disorder, and they sometimes use topiramate to augment psychotropics, or to counteract the weight gain associated with numerous antidepressants. In 2006, a Cochrane review concluded that there is insufficient evidence on which to base any recommendations regarding the use of topiramate in any phase of bipolar illness. However, a more recent Cochrane review, published in 2010, concluded that there was evidence for the efficacy of topiramate in the treatment of symptoms of borderline personality disorder, including mood instability.