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 t heir breasts using a breast pump and then received 70 mug carbetocin b y intramuscular injection. Using a radioimmunoassay, the concentration s of carbetocin were measured in plasma and breast milk samples obtain ed before carbetocin administration and at 15, 30, 60, 90, 120, and 24 0 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 th e mean AUC for carbetocin in breast milk (18.6 +/- 13.7 and 29.0 +/- 2 3.8 pg/mL for the right and left breast, respectively). The ratio of m ilk to plasma AUC was low: 1.7 +/- 0.9 and 3.1 +/- 2.8% for the left a nd right breast, respectively. No serious adverse reactions occurred a nd no clinically significant changes in vital signs were found. Conclu sion: Very little carbetocin is transferred into human breast milk, pr esenting little risk to breast-fed infants.