Treatment of porphyric convulsions with magnesium sulfate.

We report a 16-year-old girl with acute intermittent porphyria who had abdominal pain, generalized tonic-clonic and simple partial seizures, and inappropriate antidiuretic hormone secretion. Because most antiepileptic drugs are contraindicated in porphyria, she was treated with magnesium sulfate i.v. Soon after starting treatment, seizures stopped, returned, and then again responded in several trials with discontinuation and reinstitution of i.v. magnesium sulfate. Our experience encourages the use of magnesium sulfate for treatment of seizures in patients with porphyria.