Zonisamide and associated oligohidrosis and hyperthermia

Zonisamide is an antiepileptic agent that is indicated as adjunctive therapy for the treatment of partial seizures in adults. Oligohidrosis has been reported in a small number of patients receiving zonisamide and, in a proportion of these patients, hyperthermia has occurred. Most reports of hyperthermia have been in children, typically occurring during the summer months. However, the mechanism of zonisamide-associated oligohidrosis is not fully understood. Thirteen events of oligohidrosis, or hyperthermia, associated with zonisamide were reported in the US during the 3 years after zonisamide was approved, an estimated incidence of 1 case per 4590 patient-years. These events happened mostly in children. In Japan, all reported cases of zonisamide-associated oligohidrosis or hyperthermia have been in children, with an incidence of 1 case per 10,000 pediatric-years during the first 11 years of marketing. In each case, oligohidrosis was reversible upon discontinuation of zonisamide. Ensuring that children remain cool and well hydrated during hot weather can minimize the potential for hyperthermia resulting from oligohidrosis.