A seizure is an abnormal and unregulated electrical discharge occurring in the brain. This leads to a transient interruption in brain function, manifested by reduced alertness, abnormal sensations, and focal involuntary movements or convulsions. Several types of seizures exist, with common types including tonic-clonic seizures and partial onset seizures.
The exact mechanisms by which topiramate exerts pharmacological actions on seizures and migraines are currently not fully characterized. Several properties of this drug, however, are likely to contribute to its therapeutic effects. Topiramate has been observed to exert actions on voltage-dependent sodium channels, GABA receptors, and glutamate receptors.
Topiramate stimulates GABA-A receptor activity at brain non-benzodiazepine receptor sites and reduces glutamate activity at both AMPA and kainate receptors. Normally, GABA-A receptors are inhibitory and glutaminergic receptors are stimulatory for neuronal activity. By increasing GABA activity and inhibiting glutamate activity, topiramate blocks neuronal excitability, preventing seizures and migraines. Additionally, it blocks the voltage-dependent sodium channels, further blocking seizure activity. Topiramate has been shown to inhibit various carbonic anhydrase isozymes, but the clinical significance of this is unknown at this time.
Epilepsy: Topiramate is indicated as monotherapy in adults and children aged 6 years and above with newly diagnosed epilepsy who have generalised tonic-clonic seizures or partial seizures with or without secondarily generalised seizures. Topiramate is indicated as adjunctive therapy for adults and children over 2 years of age who are inadequately controlled on conventional first line antiepileptic drugs for partial seizures with or without secondarily generalised seizures; seizures associated with Lennox Gastaut Syndrome and primary generalised tonic-clonic seizures.
Migraine: Topiramate is indicated in adults for the prophylaxis of migraine headache. Prophylactic treatment of migraine may be considered in situations such as: adults experiencing three or more migraine attacks per month; frequent migraine attacks that significantly interfere with the patient's daily routine. Continuing therapy should be reviewed every six months.
Hypersensitivity to any component of this product.
Topiramate should not be used during pregnancy unless, in the opinion of the physician, the potential benefit outweighs the potential risk to the foetus. Topiramate should not be used during breastfeeding.
In patients with or without a history of seizures or epilepsy, antiepileptic drugs, including topiramate, should be gradually withdrawn to minimize the potential for seizures or increased seizure frequency. Topiramate can produce central nervous system-related adverse events and may be more sedative than other antiepileptic drugs. Drowsiness is a likelihood. In addition, there have been reports of visual disturbances/blurred vision. Patients should be warned of these and advised that if affected, they should not drive, operate machinery and/or take part in activities where such reactions could put themselves or others at risk.
Topiramate overdose can result in severe metabolic acidosis. In acute topiramate overdose, if the ingestion is recent, the stomach should be emptied immediately by lavage or by induction of emesis. Activated charcoal has been shown to adsorb topiramate in vitro. Treatment should be appropriately supportive. Haemodialysis has been shown to be an effective means of removing topiramate from the body. The patient should be well hydrated.
Adjunct anti-epileptic drugs
Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.
