Transfer of carbetocin into human breast milk.
OBJECTIVE
To study the transfer of carbetocin into human breast milk.


METHODS
Five healthy nursing women, 7-14 weeks postpartum, emptied their breasts using a breast pump and then received 70 micrograms carbetocin by intramuscular injection. Using a radioimmunoassay, the concentrations of carbetocin were measured in plasma and breast milk samples obtained before carbetocin administration and at 15, 30, 60, 90, 120, and 240 minutes after drug administration.


RESULTS
For plasma, the mean (+/- standard deviation) area under the curve (AUC) of carbetocin versus time was 1119.3 +/- 315.9 pg/mL, a value about 50 times higher than the mean AUC for carbetocin in breast milk (18.6 +/- 13.7 and 29.0 +/- 23.8 pg/mL for the right and left breast, respectively). The ratio of milk to plasma AUC was low: 1.7 +/- 0.9 and 3.1 +/- 2.8% for the left and right breast, respectively. No serious adverse reactions occurred and no clinically significant changes in vital signs were found.


CONCLUSIONS
Very little carbetocin is transferred into human breast milk, presenting little risk to breast-fed infants.
Silcox
J
J
Department of Obstetrics and Gynecology, Victoria Hospital, London, Ontario, Canada.
Schulz
P
P
Horbay
G L
GL
Wassenaar
W
W
D000328:Adult; D005260:Female; D006801:Humans; D008895:Milk, Human / Q000737:chemistry*; D010120:Oxytocics / Q000032:analysis / Q000493:pharmacokinetics*; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000032:analysis / Q000493:pharmacokinetics; D049590:Postpartum Period
D010120:Oxytocics; D010121:Oxytocin; C020731:carbetocin