Background: Breast milk is considered optimal nutrition for all infants, even in the neonatal intensive care unit. Increasingly, mothers of preterm infants are encouraged to express breast milk for their newborns. However, providing an adequate milk supply for preterm infants can be difficult, and medications such as domperidone and metoclopramide (Reglan) are often used to increase the milk supply.

The off-label use of these agents is widespread in Australia, Canada, the United Kingdom, Japan, and many countries in western Europe. The U.S. Food and Drug Administration (FDA) issued a warning in 2004 that women who were breastfeeding should not use domperidone. This was attributed to an increased risk of cardiac arrhythmia and sudden death among hypokalemic patients with cancer who were receiving high doses of intravenous domperidone concurrently with chemotherapy. This warning has been challenged in the literature by letters written to the FDA that support the safety of domperidone in lactating women.

Domperidone augments lactation by increasing prolactin concentration. The galactagogue dosage of 10 to 20 mg three times per day is less than the maximum approved oral dosage, and is generally well tolerated. Domperidone does not cross the blood-brain barrier and is excreted only minimally into breast milk. Metoclopramide has been known to decrease protein concentration and change the electrolyte composition of breast milk; however, the effect of domperidone on breast milk composition had not been studied previously. Campbell-Yeo and colleagues conducted a randomized, double-blind, placebo-controlled study to evaluate the effects of domperidone on the composition of preterm breast milk.

The Study: The authors enrolled mothers who delivered before 31 weeks' gestation and who had experienced lactation failure at least three weeks after delivery. The study was conducted between 2003 and 2007 at the IWK Health Centre in Halifax, Nova Scotia. Women were eligible for inclusion if their milk supply had decreased by more than 30 percent of peak volume, or if they were not able to produce enough milk to meet their newborn's daily intake. Women were excluded if they were already taking domperidone or any medication known to alter or interact with it; or if they had mastitis, chronic illness, previous breast surgery, or known lactose intolerance. The primary outcome was the change in breast milk protein concentration, with secondary outcomes of changes within patients of fat, carbohydrate, lactose, energy, calcium, phosphate, and sodium concentration; daily breast milk volume; prolactin levels; and breastfeeding rates two weeks after study completion and at infant's discharge. Women enrolled in the study took 10 mg of domperidone three times a day or an identical placebo for two weeks, and recorded baseline and daily milk volumes. Samples were collected on days 0, 4, 7, and 14 for protein and electrolyte analysis.

Results: The study was powered to detect a change of 20 percent or more in protein content in the domperidone group compared with the placebo group. Of the 278 mothers who delivered before 31 weeks' gestation, 46 provided informed consent and were randomized to participate (22 in the domperidone group, 24 in the placebo group). The mean within-patient breast milk volume increased by 267 percent in the domperidone group and by 19 percent in the placebo group. Protein and fat concentration did not change significantly, although the carbohydrate concentration increased 2.7 percent in the domperidone group and decreased 2.7 percent in the placebo group (P = .05). No adverse events were reported in mothers or infants.

Conclusion: The authors conclude that domperidone notably increases breast milk volume without substantial changes to breast milk composition.