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Elan Warns of Sweating Disorder in Pediatric Zonegran Users

Kate Traynor

Elan Pharmaceuticals Inc. has updated the labeling (PDF) for the company's zonisamide product, Zonegran, to warn that children who use the antiseizure drug may be at increased risk for hyperthermia and reduced sweating, or oligohidrosis.

In a letter (PDF) to health care professionals, Elan reported that 39 children in Japan and 2 in the United States are known to have suffered oligohidrosis after taking zonisamide. According to the letter, none of these patients died, but some suffered heat stroke and required hospitalization.

An 18-year-old patient in the United States is also reported to have suffered heat stroke after using the drug, but Elan described no other cases of such complications in adults who used zonisamide.

Zonisamide has been marketed in Japan since 1989 under the brand name Excegran. The drug was approved for sale in the United States in 2000 as adjunctive therapy for the treatment of partial seizures in adults with epilepsy. Zonisamide has not been approved for use in pediatric patients, and Elan's letter to health care professionals stresses that the drug's safety and effectiveness in children have not been established.

Elan advised health care practitioners to monitor all zonisamide users, especially children, for signs of decreased sweating and increased body temperature. The company noted that children seem to be at greater risk for oligohidrosis and hyperthermia during warm or hot weather.

The letter to health care practitioners asked that all cases of oligohidrosis and hyperthermia among zonisamide users be reported to Elan at 888-638-7605 or to the Food and Drug Administration's MedWatch program (telephone 800-FDA-1088; fax 800-FDA-0178).

Elan reported more than $50 million in U.S. sales of zonisamide in 2000 and 2001. The company's 2001 annual report describes zonisamide as "the fastest growing anti-epileptic drug in the United States."