Effectiveness of cyproheptadine in decreasing plasma ACTH concentrations in Nelson's syndrome.

Cyproheptadine (24 mg q.d.) was administered to four patients with Nelson's Syndrome for a 3-5 month period. This resulted in a significant reduction in plasma ACTH and prolactin concentrations in 3 of these subjects. A rise in plasma ACTH concentrations occurred following discontinuance of medication in one patient. The results suggest that pituitary ACTH secretion in some patients with Nelson's Syndrome is under Central Nervous System control.