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Topiramate
is an anticonvulsant indicated in the treatment of epilepsy
and migraine. Topiramate enhances GABA-activated chloride
channels. In addition, topiramate inhibits excitatory
neurotransmission, through actions on kainate and AMPA
receptors. There is evidence that topiramate has a specific
effect on GluR5 kainate receptors. It is also an inhibitor
of carbonic anhydrase, particular subtypes II and IV, but
this action is weak and unlikely to be related to its
anticonvulsant actions, but may account for the bad taste
and the development of renal stones seen during treatment.
Its possible effect as a mood stabilizer seems to occur
before anticonvulsant qualities at lower dosages. Topiramate
inhibits maximal electroshock and pentylenetetrazol-induced
seizures as well as partial and secundarily generalized
tonic-clonic seizures in the kindling model, findings
predective of a broad spectrum of antiseizure activities
clinically. |