Effect of parity on pituitary prolactin response to metoclopramide and domperidone: Implications for the enhancement of lactation

OBJECTIVE: The gastrointestinal motility agents metoclopramide and domperid one are known to increase pituitary prolactin (PRL) secretion and breast mi lk production. This study compared the effect of single doses of two streng ths of metclopramide and a single dose of domperidone on PRL secretion. METHODS: Ten pregnant women had baseline evaluation of serum PRL concentrat ions. The PRL concentrations were then determined after random oral adminis tration of metoclopramide 10 mg, metoclopramide 5 mg, and domperidone 10 mg . Blood samples were drawn in the first 7 days of the menstrual cycle, at 1 3 time points over a 6-hour period (0, 15, 30, 45, 60, 75, 90, 120, 150, 18 0, 240, 300, and 360 minutes), with the zero time point beginning at 0800 h ours. Variables such as weight, height, age, gravidity, parity, and oral co ntraceptive use were recorded. RESULTS: Baseline PRL concentrations showed the natural circadian rhythm. M etoclopramide and domperidone both caused a significant increase in PRL. Ho wever PRL secretion was most influenced by parity. Nulliparous women had th e quickest and highest PRL secretion with metoclopramide 10 mg, compared wi th the PRL response with metoclopramide 5 mg and domperidone 10 mg. Convers ely, multiparous women had PRL secretion patterns that were equivalent betw een the medications. Conclusions: The PRL response to the medications was most influenced by par ity. Therefore, we suggest that the medication therapy of choice for enhanc ing lactation may not be the same in all women, but may instead be determin ed by parity. Copyright (C) 2000 by the Society for Gynecologic Investigati on.