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Forty patients with hyperprolactinaemia were treated with metergoline (8 to 12 mg/day) for periods up to 5 years. Analysis of the results of clinical and biological tolerability showed that treatment was generally well tolerated and although 28 patients complained of drug-related side-effects of various kinds, principally nausea, these were usually mild, present at the beginning of treatment and disappeared spontaneously in spite of continued metergoline administration over a prolonged period. No patient stopped treatment because of side-effects. Laboratory parameters also stayed within normal levels and there was no evidence of any alterations in the ECG. It is concluded, therefore, that metergoline is a well-tolerated as well as an effective ergolinic compound for use in those patients in whom prolonged treatment with a prolactin-lowering drug is considered necessary.

Benserazide, an extra-cerebral inhibitor of dopa-decarboxylase, elicits prolactin (Prl) release in normal subjects when administered po. The aims of this study were to characterize the effect of benserazide on Prl release and to evaluate benserazide as a diagnostic tool in hyperprolactinaemic patients. In normal subjects, the effect of 50 mg benserazide is reduced to a greater extent by 500 mg than by 200 mg 1-dopa, and is nullified by dopamine (DA, 50 mg iv in 180 min), which also decreases fasting plasma Prl levels. Doses of 25, 50 and 150 mg benserazide elicit Prl responses which are slightly and progressively but not significantly higher; a second dose of 50 mg, administered 150 min later, is without effect on Prl release, while TRH (200 μg iv) elicits a further Prl peak. Since it is known that consecutive doses of TRH yield progressively lower Prl responses while 5-hydroxytryptophan (the precursor of serotonin) further increases Prl release in response to benserazide, we hypothesize that, in an area involving both the hypothalamus and the pituitary gland, anti-DA drugs (benserazide), TRH, and serotonin stimulate Prl release by interacting with different kinds of receptors. When administered to hyperprolactinaemic patients, benserazide stimulated Prl release in puerperal women and in patients with functional hyperprolactinaemias, but was totally ineffective in patients with pituitary adenomas, whatever the fasting plasma Prl levels. In 2 patients with a normal sellar tomography in whom benserazide induced no Prl release, a second tomography or computerized axial tomography of the brain, performed respectively 3 and 6 months later, revealed a pituitary microadenoma. These results suggest that benserazide may be a valuable diagnostic tool in the differential diagnosis of hyperprolactinaemia.

84 patients with elevated serum PRL levels, ranging from 25 to 253 ng/ml, were treated with an antiserotonin agent, metergoline, at the dose of 12 mg/day for 90 days. The clinical complaint was of amenorrhea in 70 cases (plus galactorrhea in 44 cases) and of anovulation in 14 cases (plus galactorrhea in 6 cases). Hyperprolactinemia was due to a pituitary adenoma in 18 cases; in 53 cases it was of unknown origin, while in 7 cases it followed treatment with neuroleptics or with oral contraceptives and in 6 cases it followed a puerperium. In patients with amenorrhea, metergoline induced the appearance of menses in 61 cases (94%), and of ovulation in 46 cases (82%). In 13 of the 14 patients with anovulation, ovulation was restored. Galactorrhea disappeared in 40 out of 50 patients. Metergoline normalized serum PRL levels (less than 20 ng/ml) in 46 cases and significantly reduced serum PRL levels in all but 3 of the remaining patients. In spite of suggested nonhormonal contraceptive measures, 14 patients became pregnant; 2 had abortions and the remaining 12 patients completed by vaginal delivery, uneventful pregnancies. These results indicate metergoline as a safe and effective drug in the management of hyperprolactinemic amenorrhea and anovulation. 49 patients were followed for 2 additional months, receiving no treatment (24 cases) or metergoline at a reduced daily dosage (8 mg/day, 25 cases). Within 60 days, 60% of the first group had relapse of the clinical condition and a rebound elevation of serum PRL levels while only 20% of the second group experienced relapse of amenorrhea and rebound elevation of serum PRL levels (p less than 0.01).