Prolactin Secretion in Patients Treated With Various Drugs

Abstract

Serum prolactin levels were determined in psychiatric or hypertensive patients and in normal volunteers receiving therapeutic doses of various phenothiazines, tricyclic antidepressants, reserpine, or methyldopa. Treatment with phenothiazine or tricyclic medications was associated with markedly elevated serum prolactin values in the range typical of postpartum lactation. Patients on a regimen of reserpine or methyldopa also had markedly elevated serum prolactin levels. Intramuscular injection of 50 mg of chlorpromazine hydrochloride resulted in prolactin secretion in normal subjects within 30 minutes. After discontinuance of phenothiazine tranquilizers, elevated prolactin levels persisted for two to three weeks. Effects of all these medications in man resemble those observed in experimental animals, in which depletion of hypothalamic catecholamine stores by these agents removes the inhibitory influence of the hypothalamus over prolactin secretion by the pituitary. These results contain implications for clinical practice and for the investigation of neuroendocrine regulatory mechanisms in man.