No Transfer of Merotocin (FE 202767) to Breast Milk in Postpartum Women: A Novel Short-Acting Oxytocin Receptor Agonist for the Induction and Support of Lactation [ID: 1370662]

INTRODUCTION: Establishing lactation after preterm birth is challenging, and there are no approved therapies. Merotocin (FE 202767) is a potent, short-acting, selective oxytocin-receptor agonist in clinical development for induction and support of lactation. This phase 1, open-label, parallel-group study of early postpartum women and women with established lactation investigated possible transfer of merotocin from plasma to breast milk. METHODS: Merotocin was administered as a single 90-minute intravenous (IV) infusion mimicking the intranasal pharmacokinetic profile. In part A, 12 early postpartum women received doses of 5 micrograms (n=6) or 20 micrograms (n=6) merotocin within 4 days of delivery. In part B, 6 women with established lactation received 20 micrograms of merotocin. The total amount of merotocin excreted in breast milk was determined, as well as the presence of metabolites of merotocin in breast milk, and adverse events. The IV route was chosen to minimize the variability in bioavailability often observed with nasal sprays. Institutional review board approval was obtained for the study. RESULTS: In all women (mean age, 26.3 years; 83.3% Caucasian) and at all time points, merotocin in breast milk was below the limit of quantification (25 pg/mL). Merotocin metabolites were not detected in any milk samples. Sixteen treatment-emergent adverse events occurred in early postpartum women only: including seven uterine spasms, and three breast engorgements. All events were mild except one moderate. CONCLUSION: Merotocin is not transferred into breast milk at quantifiable amounts, and is well tolerated. This study supports the evaluation of merotocin in an ongoing phase 2 study in women with preterm delivery (NCT02545127).