Effects of phenytoin on serum gamma-glutamyl transpeptidase activity

Epilepsia. 1981 Jun;22(3):331-8. doi: 10.1111/j.1528-1157.1981.tb04117.x.


Serum gamma-glutamyl transpeptidase (gamma-GT) activity was significantly (p less than 0.001) elevated in 85 (49.7%) out of 171 epileptics receiving anticonvulsant therapy. The effects of phenytoin, phenobarbital, carbamazepine, and valproate sodium on gamma-GT activity were analyzed statistically. Among these anticonvulsants, only phenytoin seemed to be responsible for the elevation of gamma-GT activity, since its daily dose and serum level were significantly (p less than 0.05) related to the gamma-GT value. Fifteen out of 17 epileptics with abnormal serum glutamic pyruvic and/or oxaloacetic transaminase levels also showed considerable elevations of gamma-GT values. The possible relationships between the enzyme induction of liver microsomes or chronic hepatic toxicity and the elevation of serum gamma-GT activity in epileptics under treatment are also discussed.

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Child
  • Child, Preschool
  • Dose-Response Relationship, Drug
  • Enzyme Induction
  • Epilepsy / drug therapy
  • Epilepsy / enzymology*
  • Humans
  • Liver / enzymology
  • Middle Aged
  • Phenytoin / adverse effects*
  • Phenytoin / blood
  • Time Factors
  • gamma-Glutamyltransferase / blood*


  • Phenytoin
  • gamma-Glutamyltransferase