Domperidone is a dopamine-2 (D2) receptor antagonist that stimulates the release of stored prolactin in the anterior pituitary. It is prescribed off-label in Canada and Australia to promote lactation in prolactin-deficient women. The case of a 43-year-old woman taking a high daily dose of domperidone (160 mg) is described from the InfantRisk Center Human Milk Biorepository. Milk samples were analyzed using a high-performance liquid chromatography-mass spectrometry method, detecting an average domperidone concentration of 7.0 ng/mL (range 6.2 to 8.4 ng/mL). Even at high doses, the transfer of domperidone into breast milk was negligible with a relative infant dose (RID) of 0.05%. The RID estimates the infant's potential exposure to a drug via lactation as a percentage of the weight-adjusted maternal dose. The standard threshold for reasonable infant exposure is an RID of 10%.
Keywords: domperidone; galactagogue; lactation pharmacology.