Endocrine profile and therapeutic employment of a new prolactin-lowering drug, metergoline.

Abstract

Metergoline is an ergoline derivative with potent peripheral and central antiserotoninergic properties which has recently been shown to possess a marked prolactin (PRL)-lowering activity. This drug significantly decreases serum PRL levels after acute administration in normal subjects, in puerperal women, and in most hyperprolactinemic patients with or without pituitary tumor. Its PRL-lowering effect is unaffected by pimozide pretreatment in healthy subjects, and is frequently dissociated from that of bromocriptine in hyperprolactinemic patients. The drug does not affect the secretion of growth hormone (GH), thyrotropin and gonadotropins, while it blunts the corticotropin response to centrally but not peripherally-acting stimuli in normal subjects. In acromegalics, metergoline reduces serum PRL as well as GH levels, both actions being prevented by pimozide pretreatment. Improvement in oral glucose tolerance with unchanged insulin secretion is observed after a short course of metergoline treatment in patients with chemical diabetes. The PRL-lowering action of the drug is sustained during chronic treatment in hyperprolactinemic subjects. Inhibition of puerperal lactation may be obtained by a few days metergoline treatment in almost all treated women. Normalization of serum PRL levels and restoration of cyclic ovarian function are achieved within 1–4 months of treatment with the drug in most women with hyperprolactinemic amenorrhea. The possible role of metergoline in the treatment of other endocrine disorders such as normoprolactinemic amenorrhea, sexual impotence, Cushing’s disease, acromegaly and mild diabetes mellitus remains to be determined. Although the PRL-lowering effect and the therapeutic employment of metergoline