Used for the treatment and control of partial seizures and severe tonic-clonic (grand mal) seizures and also for the prevention of migraine headaches. In children it is also used for treatment of Lennox-Gastaut syndrome.
Topamax Mechanism Of Action:
The precise mechanism of action of topiramate is not known. However, studies have shown that topiramate blocks the action potentials elicited repetitively by a sustained depolarization of the neurons in a time-dependent manner, suggesting a state-dependent sodium channel blocking action. Topamax also augments the activity of the neurotransmitter gamma-aminobutyrate (GABA) at some subtypes of the GABAA receptor (controls an integral chloride channel), indicating a possible mechanism through potentiation of the activity of GABA. Topamax also demonstrates antagonism of the AMPA/kainate subtype of the glutamat excitatory amino acid receptor. It also inhibits carbonic anhydrase (particularly isozymes II and IV), but this action is weak and unlikely to be related to its anticonvulsant actions.
Symptoms of overdose include abdominal pain, agitation, blurred vision, convulsions, depression, dizziness, double vision, drowsiness, impaired coordination, impaired mental activity, low blood pressure, reduced consciousness, severe diarrhea, sluggishness, and speech problems.
Not extensively metabolized, 70% of the dose is eliminated unchanged in the urine. The other 30% is metabolized hepatically to six metabolites (formed by hydroxylation, hydrolysis, and glucuronidation), none of which constitute more than 5% of an administered dose.