Effect of ethosuximide on cortisol metabolism in the treatment of congenital adrenal hyperplasia.

BACKGROUND

Antiepileptics may affect cortisol metabolism through CYP3A4. There is little known about ethosuximide.

METHODS

Our patient is a 12-year-old girl with salt-wasting congenital adrenal hyperplasia (CAH) owing to 21 hydroxylase deficiency. A standard treatment regimen was initiated with satisfactory results until the age of 6 years, when she developed absence seizures treated with ethosuximide. She received such therapy until the age of 12 years, at which point ethosuximide was discontinued. During ethosuximide administration, she experienced worsening control of CAH disease activity that responded to progressive increases in hydrocortisone dose up to 28 mg/m2 per day. Despite high doses of hydrocortisone, she suffered no cushingoid symptoms. Her requirements for high glucocorticoid replacement doses resolved shortly after ethosuximide was discontinued. We provide data over 6 years demonstrating a correlation between adrenal hormone secretion, cortisol requirements and ethosuximide dose.

CONCLUSIONS

This is the first case demonstrating an interaction between ethosuximide and hydrocortisone clearance in the treatment of salt-wasting CAH.