title: Amlodipine passage into breast milk in lactating women with pregnancy-induced hypertension and its estimation of infant risk for breastfeeding.
abstract: BACKGROUND
  Few clinical reports have been published on amlodipine passage into breast milk in lactating women.
  
  
  OBJECTIVE
  The aims of this study were to evaluate the plasma concentration of amlodipine and its passage into breast milk in lactating women with pregnancy-induced hypertension and to estimate the risk for breastfeeding infants.
  
  
  METHODS
  Thirty-one lactating women receiving oral amlodipine once daily for pregnancy-induced hypertension were enrolled. Pre-dose plasma and milk concentrations of amlodipine were determined at day 6 or later after starting the medication. Relative infant dose (RID) as an infant risk for breastfeeding was calculated by dividing the infant dose via milk by the maternal dose.
  
  
  RESULTS
  The mean maternal dose of amlodipine was 6.0 mg. The medians of the plasma and milk concentrations of amlodipine were 15.5 and 11.5 ng/mL, respectively. Interindividual variation was observed in the amlodipine dose and body weight-adjusted milk concentrations (interquartile range [IQR], 96.7-205 ng/mL per mg/kg). The median and IQR of the amlodipine concentration ratio of milk to plasma were 0.85 and 0.74 to 1.08, respectively. The medians of infant birth weight and daily amlodipine dose via milk were 2170 g and 4.2 μg/kg, respectively. The median of the RID of amlodipine was 4.2% (IQR, 3.1%-7.3%).
  
  
  CONCLUSIONS
  Lactating women with pregnancy-induced hypertension had higher plasma concentrations of amlodipine during the early postpartum period. Oral amlodipine transferred into breast milk at the same level as that of plasma. However, the RID of amlodipine in most patients was less than 10%.
authors.affiliation: Department of Hospital Pharmacy, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan naitou@hama-med.ac.jp.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Naito
authors.affiliation: Department of Hospital Pharmacy, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Kubono
authors.affiliation: Biological Research Department, Sawai Pharmaceutical Co, Ltd, Osaka, Osaka, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Deguchi
authors.affiliation: Biological Research Department, Sawai Pharmaceutical Co, Ltd, Osaka, Osaka, Japan.
authors.forename: Masahisa
authors.initials: M
authors.lastname: Sugihara
authors.affiliation: Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Itoh
authors.affiliation: Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Kanayama
authors.affiliation: Department of Hospital Pharmacy, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Kawakami
mesh_terms: D000284:Administration, Oral; D000328:Adult; D017311:Amlodipine / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D000959:Antihypertensive Agents / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D001942:Breast Feeding; D005260:Female; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000188:drug therapy*; D007231:Infant, Newborn; D007774:Lactation; D008297:Male; D008895:Milk, Human / Q000378:metabolism*; D011247:Pregnancy; D012307:Risk Factors
chemical_list: D000959:Antihypertensive Agents; D017311:Amlodipine
keywords: amlodipine; breast milk; breastfeeding; pharmacokinetics; pregnancy-induced hypertension; relative infant dose