In 118 adult epileptic patients with grand mal and/or temporal-limbic epilepsy, the mean serum concentration of diphenylhydantoin, phenobarbital, primidone, and phenobarbital derived from primidone increased directly with mean dose administered. With a given dose of each drug, wide individual variation in serum concentration existed. Women consistently received a larger dose of each medication per unit of body weight than men, yet women uniformly obtained lower serum concentrations of each drug. Those subjects with more frequent and/or more poorly controlled seizures received the largest doses of diphenylhydantoin and phenobarbital and obtained higher serum concentrations of these drugs than those patients with less frequent and better controlled seizures. Men and women were unevenly distributed with regard to seizure frequency and control. The heterogenous nature of a population of seizure patients was emphasized.
Travers RD, Reynolds EH, Gallagher BB. Variation in Response to Anticonvulsants in a Group of Epileptic Patients. Arch Neurol. 1972;27(1):29–33. doi:10.1001/archneur.1972.00490130031004