Morphine suppresses the oxytocin response in breast-feeding women.
The activity of opiate-mediated regulatory mechanisms of oxytocin secretion during breast-feeding was studied by the administration of either morphine, naloxone or placebo to women prior to the commencement of breast-feeding. Seventeen healthy women in the first week after delivery who had established lactation were randomized to receive either intravenous morphine 5 mg (n = 6), naloxone 2.4 mg (n = 6) or a placebo, sterile water (n = 5), which was given prior to commencement of breast-feeding. Oxytocin levels were measured by radioimmunoassay prior to initiation of breast-feeding and then at 2-min intervals until the feed was complete. Breast-feeding produced a significant rise in oxytocin levels in the control and naloxone groups but no significant rise in the patients given morphine. There was a significant reduction in oxytocin response following morphine administration when compared to placebo but not between naloxone and placebo. In conclusion, oxytocin secretion to breast-feeding is inhibited by exogenous morphine when compared to a control group but the administration of naloxone did not produce a significant difference from control.
Department of Obstetrics and Gynaecology, Medical School, University of Cape Town, Observatory, South Africa.
S W
SW
Lindow
M S
MS
Hendricks
F A
FA
Nugent
T T
TT
Dunne
Z M
ZM
van der Spuy
D000328:Adult; D001942:Breast Feeding; D005260:Female; D006801:Humans; D007774:Lactation / Q000187:drug effects* / Q000502:physiology; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D010121:Oxytocin / Q000097:blood / Q000378:metabolism*; D010919:Placebos
D009292:Narcotic Antagonists; D009294:Narcotics; D010919:Placebos; D009270:Naloxone; D010121:Oxytocin; D009020:Morphine