Aims: To investigate the possibility of a dose-response relationship for the use of domperidone in treating insufficient milk supply in mothers of preterm infants, and to quantify the exposure of the breastfed infant to domperidone.
Methods: Six preterm mothers received domperidone (30 mg daily or 60 mg daily) in a double-blind, randomized, crossover trial. Milk production and serum prolactin were measured before and during the trial, and domperidone concentration in milk was measured during drug treatment.
Results: For milk production, two of the mothers were 'nonresponders', whereas the other four were 'responders' and showed a significant increase in milk production from 8.7 +/- 3.1 g h(-1) in the run-in phase (mean +/- SEM), 23.6 +/- 3.9 g h(-1) for the 30-mg dose (P = 0.0217) and 29.4 +/- 6.6 g h(-1) for the 60-mg dose (P = 0.0047). In all participants, serum prolactin was significantly increased for both doses, but the response was not dose dependent. Median (interquartile range) domperidone concentrations in milk over a dose interval at steady-state were 0.28 microg l(-1) (0.24-0.43) and 0.49 microg l(-1) (0.33-0.72) for the 30-mg and 60-mg doses, respectively. The mean relative infant dose was 0.012% at 30 mg daily and 0.009% at 60 mg daily.
Conclusion: In one-third of mothers, domperidone did not increase milk production. In the remainder, milk production increased at both domperidone doses, and there was a trend for a dose-response relationship. The amount of domperidone that transfers into milk was extremely low, and infant exposure via breastfeeding was not considered to be significant.