n. an anticonvulsant that is also used as a mood stabilizer in the treatment of bipolar disorders, although not with well-established efficacy. Additionally, it is used for weight loss and for migraine prevention. Topiramate works by slowing neurotransmission through blockade of sodium channels (see ion channel); it also may facilitate the activity of the neurotransmitter gamma-aminobutyric acid (GABA) and limit activity at glutamate receptors. Psychomotor slowing and somnolence are commonly reported adverse effects. U.S. trade name: Topamax.