About 70 million people worldwide are estimated to suffer from epilepsy. Despite a large variety of old and new antiepileptic drugs on the market, about 30% of people with epilepsy do not become seizure-free with medical treatment. This is a major individual and public health burden. Most of these difficult-to-treat patients are having focal seizures. Zonisamide is effective against focal seizures in adults and children and, thus, a therapeutic option for such patients. Its safety profile needs special attention. Areas covered: Herein, the authors discuss the pharmacology, clinical efficacy and the adverse effects of zonisamide. The article is derived from clinical trial data, long-term studies, meta-analyses, review articles, text books, webpages, and official license information. Expert opinion: Zonisamide has proven to be efficacious in focal epilepsy in children and adults, although it is not more effective than carbamazepine or other antiepileptic drugs. It is also effective in generalized epilepsy and in several other conditions of the CNS. Its safety profile may prevent it from becoming a first-line drug for focal epilepsy or any other indication.
Keywords: Cognitive adverse effect; drug safety; epilepsy; gastrointestinal adverse effects; long-term efficacy; mechanism of action; monotherapy; pharmacokinetics; psychiatric adverse effects; retention rate.