Topiramate is indicated for the prevention of migraine in adults. It is taken by mouth as preventive therapy to reduce migraine frequency. For those with frequent migraine attacks, or migraine that do not respond to acute treatment, preventive medications can be important. Pharmacology: Pharmacodynamics: Topiramate is classified as a sulfamate-substituted monosaccharide. The precise mechanism by which topiramate exerts its antiseizure and migraine prophylaxis effects are unknown. Researchers speculated that topiramate exhibited a multi-modal mechanism of action that was possibly useful as a migraine/headache prophylactic. The team of researchers conducted a retrospective chart review by analyzing a total of 178 patients with either: transformed migraine (96 patients), episodic migraine (70 patients), or cluster headache (12 patients). 758 Vol. 2, No. 21 November 2002 ABSTRACT Topiramate has been under investigation for the past several years as a prophylactic agent for migraine and other headache disorders. Topiramate (TPM) is one of the novel antiepileptic drugs and exhibits a wide range of mechanisms of action. Efficacy of TPM has been demonstrated in partial-onset seizures and primary generalized seizures in adults and children, as both monotherapy and adjunctive therapy. The abortive medications commonly used for migraine headaches are contraindicated in cases of hemiplegic migraines as their mechanism of action involves narrowing of blood vessels thus, preventive migraine therapy especially calcium channel blockers may be the drug of choice especially if the hemiplegic migraine is of the familial type. Topiramate, sold under the brand name Topamax among others, is a medication used to treat epilepsy and prevent migraines. It has also been used in alcohol dependence. For epilepsy this includes with generalized or focal seizures. It is taken by mouth. Patsalos, PN; (1999) The mechanism of action of topiramate. REV CONTEMP PHARMACO , 10 (3) 147 - 153. Full text not available from this repository. Topiramate also prevents migraine headaches. Seizures are due to the abnormal activity ( firing ) of nerves in the brain, and the abnormal activity spreads to smaller or larger portions of the brain. Although topiramate's exact mechanism of action is unknown, scientific studies suggest that it may alter neurotransmitters within the brain. Topiramate blocks voltage-dependent sodium and calcium channels.20,21 It also inhibits the excitatory glutamate pathway while enhancing the inhibitory effect of GABA.22,23 Moreover, it inhibits carbonic anhydrase activity.24 The relevant mechanism of action responsible for efficient migraine prophylaxis remains to be determined.