Inhibition of puerperal lactation by metergoline: interactions with methylergobasine maleate.

Metergoline, a prolactin (PRL) lowering drug, is used in the puerperal period to inhibit lactation. Methylergobasine maleate (MEM), widely employed in the puerperium to promote uterine contractions, has also been reported to decrease PRL release and to reduce lactation. To evaluate the possible interactions of the two drugs, groups of 6-11 puerperae each received no treatment, metergoline alone (8 or 12 mg/day for 5 days), MEM alone (0.2 mg i.v. at delivery followed by 0.5 mg/day p.o. for 5 days) and metergoline plus MEM. Metergoline fully prevented lactation and significantly reduced PRL release, the higher dose inducing effects faster. MEM was without effect on PRL release and lactation, and did not modify the effect of metergoline.