Antiepileptic drugs in the treatment of neuropathic pain.

Antiepileptic drugs were initially designed to treat epileptic seizures, but are increasingly used in the treatment of neuropathic pain. Efficacy of the newer antiepileptic drugs has been confirmed in placebo-controlled studies for trigeminal neuralgia, postherpetic neuralgia, painful polyneuropathy and central poststroke pain. While standard antiepileptic drugs act as sodium channel blockers, the newer antiepileptics display additional mechanisms of action, including a potentiation of GABAergic inhibition, specific binding on a subtype of calcium channels, a reduced release of glutamate and a blockade of AMPA/kainate receptors. These mechanisms could account for their antiallodynic and antihyperalgesic effects demonstrated in animal models of neuropathic pain and also suggested for gabapentin and lamotrigine in humans. Additional studies are required to compare efficacy of newer versus standard antiepileptic drugs and to better define their place in comparison with other analgesics in the treatment of neuropathic pain.