[Zonisamide and neuropathic pain]

In neuropathic pain, as occurs in epilepsy, researchers are striving to find a drug capable of inhibiting the pain-generating ectopic discharges that are produced as a result of neuronal hyperexcitability. This is mediated by ionic exchanges across the channels of the synaptic membrane. This is why the drugs that act on the different types of channels involved in this transmission can regulate neuronal hyperexcitability and therefore have an effect on the pain.

In recent years researchers have gained a deeper understanding of the mechanisms of action of antiepileptic drugs and, since the discovery of their action on one or several synaptic channels, the use of these agents to treat neuropathic pain has become increasingly common. Patients suffering from central pain are also beginning to benefit from the administration of these drugs, especially agents that have proved to be capable of acting with several mechanisms of action and on several channels at the same time. In addition, fewer and less severe side effects are produced, something that is fundamental if we bear in mind the characteristics of patients with central pain, most of whom are adults and elderly. This, together with the fact that there are fewer interactions with other drugs, has led to the new antiepileptic drugs' becoming the preferred medication for this pathology today.

Zonisamide acts on several types of channels and it is known to have four different mechanisms of action, which means it can be effective in treating these patients, although further studies are required (above all randomised double-blind trials) in order to really evaluate the usefulness of these drugs in the treatment of neuropathic pain.