Magnesium sulfate versus phenytoin for the prevention of eclampsia

To the Editor: The study by Lucas et al. (July 27 issue)¹ offered an opportunity to resolve a controversy in patient care that has divided neurologists and obstetricians for decades. However, their conclusion regarding the superiority of magnesium sulfate over phenytoin may have been influenced by several methodologic flaws. First, the loading dose of phenytoin was lower than the typical recommended dose of 18 to 20 mg per kilogram of body weight, and the reported serum levels when seizures occurred (<12.2 μg per milliliter in 8 of the 10 patients in whom eclampsia subsequently developed) are evidence of this less.