Cyproheptadine-induced remission of Cushing's disease.

Experimental evidence suggests a central-nervous-system origin of Cushing's disease and a role for serotonin in the regulation of ACTH release. The efficacy of cyproheptadine therapy, therefore, was studied in three patients with such disease. Administration of 24 mg daily over a period of three to six months was associated with prompt and sustained clinical and laboratory remission. Lessening of the physical manifestations of hypercorticism occurred, together with marked improvement in muscular weakness. Urinary corticosteroid excretion and cortisol secretory rate returned to normal. The urinary corticosteroid response to dexamethasone (2 mg per day) became normal; a paradoxical increase followed 8 mg per day. Abnormal circadian periodicity of plasma cortisol concentrations persisted. Return of normal amounts of Stage III to IV sleep occurred in the one patient so studied, who previously had markedly decreased periods of these stages. Discontinuance of therapy in one patient was associated with return of laboratory evidence of hypercorticism.