The influence of metoclopramide on the composition of human breast milk.

The breast milk prolactin (PRL) has been claimed to play a role in the control of electrolyte composition of the milk. Since metoclopramide has been shown to increase milk production in humans, we have made an attempt to investigate the production, the PRL and sodium concentrations in milk with (group I) and without (group II) maternal metoclopramide treatment (5 days, 30 mg/day). Both groups consisted of 11 mothers and their full-term newborn infants. The daily milk production was significantly higher in the treated group (276.4 +/- 36.6 vs 150.9 +/- 25.3 ml/day, p less than 0.01). The PRL measured by RIA was similar in the milk samples of the metoclopramide treated and control groups (80.5 +/- 17.7 vs 90.7 +/- 27.3 ng/ml). The sodium concentration in the milk of mothers taking metoclopramide was 22.1 +/- 1.6 mmol/l and 24.3 +/- 3.2 mmol/l in the control group (p = 0.59). On the 5th postnatal day the plasma PRL of the newborns of mothers treated with metoclopramide does not differ from the values of the control babies (29.8 +/- 2.6 vs 30.7 +/- 2.4 ng/ml) indicating that the amount of metoclopramide transferred into the milk has no apparent influence on the hypothalamo-hypophyseal axis of the neonate. In conclusion: the maternal metoclopramide treatment augments the milk production without having any effect on the PRL and sodium concentration of human "mature" milk.