Teratogenicity of zonisamide and other little-used antiseizure medications

To investigate the risk of teratogenesis occurring in relation to intrauterine exposure to infrequently used antiseizure medications in Australia.Analysis of data contained in the Raoul Wallenberg Australian Pregnancy Register of Antiepileptic Drugs.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.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.