title: Flecainide excretion in human breast milk.
abstract: Healthy human volunteers who intended not to breast feed were placed on a regimen of 100 mg oral flecainide every 12 hours for 5 1/2 days beginning 1 day after parturition. Milk and blood samples were collected during the dosing period and for 2 days after the last dose. Concentrations of flecainide in milk and plasma were assayed by HPLC. Apparent steady-state levels of flecainide in both milk and plasma were achieved in most cases by day 4 of the study. Highest daily average concentration of flecainide in milk ranged from 270 to 1529 ng/ml for the 11 subjects. Mean +/- SD milk to plasma flecainide ratios were 3.7 +/- 3.5, 3.2 +/- 2.3, 3.5 +/- 2.1, and 2.6 +/- 0.7 on study days 2, 3, 4, and 5, respectively. After the last dose of flecainide, peak milk levels of the drug occurred at 3 to 6 hours and then declined monoexponentially. The half-life for elimination of flecainide from milk was 14.7 +/- 3.5 hours and is very similar to the plasma elimination half-life of flecainide in healthy human subjects. The mean milk to plasma ratios for flecainide after the last dose were 2.3 +/- 1.0 and 2.9 +/- 1.1 at 24 and 48 hours after the dose, respectively. Based on the pharmacokinetics of flecainide in infants, the expected average steady-state plasma concentration of flecainide in a newborn infant consuming all of the milk production of its mother (approximately 700 ml/day) would not be expected to exceed about 62 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: 3M Pharmaceuticals, 3M Center, St. Paul, MN 55144.
authors.forename: R L
authors.initials: RL
authors.lastname: McQuinn
authors.forename: A
authors.initials: A
authors.lastname: Pisani
authors.forename: S
authors.initials: S
authors.lastname: Wafa
authors.forename: S F
authors.initials: SF
authors.lastname: Chang
authors.forename: A M
authors.initials: AM
authors.lastname: Miller
authors.forename: J M
authors.initials: JM
authors.lastname: Frappell
authors.forename: G V
authors.initials: GV
authors.lastname: Chamberlain
authors.forename: A J
authors.initials: AJ
authors.lastname: Camm
mesh_terms: D000293:Adolescent; D000328:Adult; D001682:Biological Availability; D005424:Flecainide / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D008895:Milk, Human / Q000032:analysis*; D049590:Postpartum Period
chemical_list: D005424:Flecainide