Prolonged dopamine receptor blockade in normoprolactinemic amenorrhea: a double-blind placebo study.

Patients with functional amenorrhea may have a raised central dopaminergic activity, leading to inhibition of pituitary-ovarian function. In a double-blind placebo trial, ten patients with amenorrhea received metoclopramide (MTC) orally in daily doses from 20 to 7.5 mg in a sequential form for 10 weeks. Six patients received placebo. Serum levels for luteinizing hormone (P less than 0.02), follicle-stimulating hormone (P less than 0.05), and prolactin (P less than 0.001) increased significantly during MTC administration, and no (P greater than 0.05) hormonal changes occurred in the placebo group. Six patients observed vaginal bleedings during MTC administration but without postovulatory progesterone levels. Dopamine receptor blockade may activate the hypothalamic-pituitary axis of amenorrheic patients, although an ovulatory response is not achieved.