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Flecainide excretion in human breast milk.
R L McQuinn1, A Pisani, S Wafa
13M Pharmaceuticals, 3M Center, St. Paul, MN 55144.
Clinical Pharmacology and Therapeutics
|September 1, 1990
Summary
Flecainide transfers into breast milk, reaching steady-state levels by day 4. Infant exposure is predicted to be low, suggesting minimal risk for breastfed newborns.
Area of Science:
- Pharmacology
- Neonatal Medicine
- Lactation Studies
Background:
- Flecainide is a Class Ic antiarrhythmic drug.
- Information on flecainide transfer into human milk is limited.
- Assessing infant exposure is crucial for maternal medication use during lactation.
Purpose of the Study:
- To quantify flecainide concentrations in milk and plasma of postpartum women.
- To determine the milk-to-plasma ratio of flecainide.
- To estimate potential flecainide exposure in breastfed infants.
Main Methods:
- Healthy non-breastfeeding postpartum women received oral flecainide (100 mg every 12 hours) for 5.5 days.
- Milk and plasma samples were collected during dosing and for 48 hours post-dose.
- Flecainide concentrations were measured using High-Performance Liquid Chromatography (HPLC).
Main Results:
- Apparent steady-state flecainide levels in milk and plasma were achieved by day 4.
- Mean milk-to-plasma ratios ranged from 2.6 to 3.7 during dosing.
- Elimination half-life in milk (14.7 ± 3.5 hours) was similar to plasma elimination half-life.
- Predicted infant plasma concentration was estimated to be below 62 ng/ml.
Conclusions:
- Flecainide transfers into breast milk.
- The milk-to-plasma ratio suggests moderate transfer.
- Estimated infant exposure is likely low, warranting further clinical assessment for safety in breastfeeding infants.