Teratogenicity of zonisamide and other little-used antiseizure medications.

PURPOSE: To investigate the risk of teratogenesis occurring in relation to intrauterine exposure to infrequently used antiseizure medications in Australia.

METHODS: Analysis of data contained in the Raoul Wallenberg Australian Pregnancy Register of Antiepileptic Drugs.

RESULTS: There was statistically significant evidence that zonisamide, but not any other of nine infrequently used antiseizure medications in Australia, was associated with a risk of teratogenesis related to the maternal dose of the drug taken in at least the earlier half of pregnancy.

CONCLUSIONS: The teratogenesis associated with zonisamide, like that associated with topiramate and possibly acetazolamide, may be an expression of a class effect shared among sulphonamide-derived carbonic anhydrase inhibitors that possess anti-seizure activity.