Cyproheptadine inhibits the corticotropin releasing hormone (CRH)--induced hormone release in normal subjects.

To further elucidate the inhibitory action of cyproheptadine on ACTH release, we studied the influence of cyproheptadine (0.1 mg/kg body weight) on the corticotropin releasing hormone (CRH)--induced hormone release in normal subjects. On two occasions six healthy volunteers underwent a CRH-test (0.1 mg hCRH as bolus i.v.) combined with an infusion of either cyproheptadine or saline starting 30 min prior to the CRH injection. Cyproheptadine led to a significant suppression of the plasma ACTH (p less than 0.05) and serum cortisol (p less than 0.005) response to CRH compared to placebo suggesting a direct inhibitory action of cyproheptadine at the pituitary level.