there are two sub-classes of calcium-channel blockers-dihydropyridines and rate-limiting-which are not generally interchangeable therapeutically (1)
nifedipine is the preferred dihydropyridine during breastfeeding
note that nifedipine has been used therapeutically in infants
verapamil is the preferred rate-limiting calcium channel blocker during breastfeeding
a previous review noted that nformation regarding the safety of calcium channel blockers during lactation is limited, although they are not likely to pose a risk to the nursing infant (2)
nifedipine
infant monitoring whilst on nifedipine (1)
as a precaution, monitor the infant for hypotension which may manifest as drowsiness, lethargy, looking pale, poor feeding and inadequate weight gain
notes
published evidence shows that nifedipine passes into breast milk in very small amounts (1.6% to 3.4% of the maternal weight-adjusted dose) after daily doses of 20 to 90mg
amounts are significantly lower than doses used therapeutically in infants from birth
no side effects have been reported in breastfed infants
verapamil
infant monitoring whilst on verapamil (1)
as a precaution, monitor the infant for hypotension which may manifest as drowsiness, lethargy, looking pale, poor feeding and inadequate weight gain
notes
published case reports have shown variable levels of verapamil in breast milk, although amounts are still negligible
infant would ingest an estimated 0.01% to 0.98% of the maternal weight-adjusted dose.
in the published cases, infant plasma levels were negligible or undetectable
no side effects have been reported in breastfed infants
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