Known as



Effective against partial seizures (including secondary generalized tonic-clonic). Somewhat effective against primary generalized tonic-clonic seizures. Ineffective against or may worsen tonic or atonic seizures. Effect unknown for absence and myoclonic seizures. Also effective against the photoparoxysmal response. Good for patients refractory to other drugs, and in patients with complex medical needs.

How to Use

  • Loading dose = 500 to 1000 mg/d
  • Maintenance dose = 1000 to 4000 mg/d, bidaily or tridaily
  • Treatment can be started at full dose at the start without fear of adverse effects

Side Effects

Generally well tolerated. Dizziness, somnolence or asthenia (lack or loss of strength) may occur in some patients. Slightly decreased red blood and white blood cell counts are occasionally seen.


No known interactions with other drugs.

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The material offered at this site is to provide general information about epilepsy to the public. It is not intended to be taken as medical advice. Although all material presented at this site has been thoroughly researched and is believed to be correct, Epilepsy Ontario accepts no liability. Consult your physician and/or neurologist with any questions you have. People with epilepsy should never discontinue anti-epileptic medications or make changes in activities unless specifically advised to do so by an attending physician.