Key Takeaways
Extended Takeaways
- In this inpatient phase 4 study, lactating women received the maximum recommended adult dose of viloxazine ER, 600 mg/d, for 3 consecutive days, which helps clinicians interpret the low milk transfer findings under a higher-exposure dosing scenario rather than a subtherapeutic one.
- Viloxazine concentrations peaked later than many immediate-release agents, with a median Tmax of 5.53 h in breast milk and 5.00 h in plasma, suggesting that drug transfer into milk tracks maternal systemic exposure over several hours after dosing.
- The breast milk-to-plasma exposure ratio for viloxazine was 0.338, indicating that milk concentrations were substantially lower than maternal plasma concentrations across the 24-hour dosing interval at steady state.
- Study-specific milk production varied widely, with a median total milk volume of 543 mL on Day 3 and a range of 182–1,259 mL, so clinicians should remember that individual infant exposure can differ even when average relative infant dose estimates are low.
- The major metabolite, 5-HVLX-gluc, showed negligible transfer into breast milk, with RID ~0.1%, which is clinically relevant because this metabolite is considered inactive and therefore unlikely to add meaningful pharmacologic exposure for the infant.
- Maternal tolerability was favorable despite starting directly at 600 mg/d: 12 (80%) participants reported 28 AEs, all were mild, no serious AEs occurred, and no participants discontinued due to any AE.
