Is Amlodipine safe while breastfeeding?

Summary of use during breastfeeding

Limited information indicates that milk levels of amlodipine are usually low and plasma levels in breastfed infants are undetectable. Maternal use of amlodipine during breastfeeding has not caused any adverse effects in breastfed infants. If the mother requires amlodipine, it is not a reason to discontinue breastfeeding.

Effects on the breastfed infant

A woman took amlodipine for hypertension 5 mg daily beginning 2 weeks postpartum. Her exclusively breastfed infant was examined regularly and at 3 months of age was healthy and had normal physical and neurological development.[5]

One woman received amlodipine 2.5 mg orally twice daily during pregnancy for hypertension associated with glomerulonephritis. The dose was increased to 5 mg twice daily on day 2 postpartum. Her exclusively breastfed infant’s growth was normal throughout the first year of life and no adverse effects were noted.[6]

A preterm infant of 32 weeks gestation was breastfed exclusively from day 7 to day 20 postpartum. The infant’s mother was taking amlodipine and labetalol in unspecified dosages for hypertension. The infant had apnea episodes unrelated to amlodipine. Growth at 2 months of age was slightly low.[4]

Thirty-one women with pregnancy-induced hypertension postpartum received amlodipine 5 mg daily by mouth, with the dosage increased as needed to maintain blood pressure of 140/90 mm Hg or less. Their breastfed (extent not stated) infants exhibited no observed adverse cardiovascular effects within 3 weeks postpartum, although exact measurement methods were not stated.[1]

A telephone survey of 43 women taking postpartum amlodipine for hypertension was conducted. Twenty-three of the women exclusively breastfed and ten mixed-fed while taking the medication. In total, 39 women reported no concerns with neonatal health. Of those with health concerns (infection, asthma, delayed closure patent ductus arteriosus, developmental delay), none of them were related to antenatal amlodipine use. One baby exposed to amlodipine antenatally was admitted to hospital for elective hernia repair at 2 months postpartum.[7]

Effects on milk supply

Relevant published information was not found as of the revision date.

Levels in milk

Maternal Levels. Thirty-one postpartum women with pregnancy-induced hypertension received amlodipine 5 mg daily by mouth, with the dosage increased as needed to maintain blood pressure of 140/90 mm Hg or less. The final mean dosage for the group was 6 mg (0.099 mg/kg) daily. Simultaneous predose maternal blood and breastmilk samples were obtained within 3 weeks postpartum, after at least 6 days of therapy. The median milk concentration was 11.5 mcg/L (intraquartile range 9.8 to 18 mcg/L). The authors calculated a median infant dosage of 4.2 mcg/kg (intraquartile range 3.1 to 6.3 mcg/kg), which corresponds to a weight-adjusted maternal dosage of 4.2% (intraquartile range 3.1 to 7.3%). However, using the median milk concentration, one would calculate an infant dosage of only 1.73 mcg/kg daily and a weight-adjusted relative dosage of 1.7%. It is unclear why the difference exists between reported and calculate values. In 5 mothers, the weight-adjusted maternal dosage was above 10%, with a maximum value of 15.2% in one mother.[1] All of these calculations are suboptimal because only single points of maternal plasma and milk concentrations were measured rather than using an area-under-the-curve to calculate them.

Six mothers were taking amlodipine 5 mg daily during pregnancy and postpartum. On the second day postpartum, 6 colostrum samples were obtained at 4, 6, 8, 12, 15 and 24 hours following the dose. Amlodipine was undetectable (<0.1 mcg/L) in all samples.[2]

Eight mothers with infants 5 to 7 days old were taking amlodipine 2.5 mg (1 subject) or 5 mg (7 subjects) daily. They donated foremilk samples at various times after the dose. Peak concentrations in milk occurred from 4 to 8 hours after a dose and ranged from 8 to 20 mcg/L in 5 women with more than 4 milk samples. The weight-adjusted maternal dosage averaged 3.3% (range 1.6% to 4.3%) among the 8 mothers.[3]

Infant Levels. A preterm infant of 32 weeks gestation was breastfed exclusively from day 7 to day 20 postpartum. The infant’s mother was taking amlodipine and labetalol in unspecified dosages for hypertension. After 4 days of breastfeeding, the infant’s blood amlodipine level was unmeasurable (lower limit of assay not specified).[4]

Eight infants whose mothers were taking amlodipine 5 mg daily during pregnancy had blood samples taken at 24 to 48 hours postpartum. Amlodipine concentrations were unmeasurable (<0.1 mcg/L) in all samples, although the paper does not state how many of the infants were being breastfed.[2]

Nine infants aged 5 to 7 days were exclusively breastfed by 8 mothers who were taking amlodipine 2.5 mg (1 mother) or 5 mg (7 mothers) daily. Blood samples were taken from the infants before and after nursing at 8 hours after their mothers’ amlodipine dose. All infant blood levels were undetectable (<0.4 mcg/L).[3]

Alternatives LactMed lists

• Nifedipine
• Nitrendipine

Amlodipine in pregnancy

LactMed covers breastfeeding only. For what the NHS and the US prescribing label say about pregnancy, see:

• Is amlodipine safe in pregnancy and breastfeeding?