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. CONCLUSION: Very little carbetocin is transferred into human breast milk, presenting little risk to breast-fed infants.
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. CONCLUSION: Very little carbetocin is transferred into human breast milk, presenting little risk to breast-fed infants.