Using calcium-channel blockers during breastfeeding

Published 2 June 2023

Topics: AmlodipineCardiovascular system disordersDiltiazem · 4 more FelodipineNifedipineSafety in BreastfeedingVerapamil · Less

Nifedipine and verapamil are the calcium-channel blockers of choice during breastfeeding. Recommendations apply to full term and healthy infants only.

General considerations

It is important to complete an individual risk assessment for your patient and to apply the principles of prescribing in breastfeeding when looking at the available information and making treatment decisions.

Recommendation

There are two sub-classes of calcium-channel blockers—dihydropyridines and rate-limiting—which are not usually interchangeable therapeutically. We have therefore only given recommended alternatives within the same sub-class.

Nifedipine (a dihydropyridine) and verapamil (rate-limiting) are the preferred calcium-channel blockers during breastfeeding, as published evidence is available about their excretion into breast milk and they have the most favourable pharmacokinetics. Additionally, nifedipine has been used therapeutically in infants.

Recommendations apply to any indication the medicine is being used for and to any formulation, including modified-release preparations.

Choice considerations

Clinical actions of calcium-channel blockers vary widely and they are used for a variety of indications, both licensed and off-label. These include hypertension, angina, arrhythmias, Raynaud’s phenomenon and cluster headache. Nifedipine is also used for painful nipple spasm which can occur during breastfeeding.

Treatment choice should be primarily directed at controlling symptoms, with suitability in breastfeeding as a secondary consideration.

For some indications a combination of medicines may be required and therefore their additive suitability in breastfeeding will need to be considered.

See also our advice on ACE inhibitors, beta-blockers and angiotensin-II receptor antagonists.

Breastfeeding itself can help to reduce the risk of cardiovascular disease, including a protective effect against hypertension.

Specific recommendations

Nifedipine

Dihydropyridine calcium-channel blocker of choice

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Preferred choice

This is a preferred choice due to very small amounts in breast milk and extensive experience of use during breastfeeding.

Infant monitoring

As a precaution, monitor the infant for hypotension which may manifest as drowsiness, lethargy, looking pale, poor feeding and inadequate weight gain.

Further information

Published evidence from several studies 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. These amounts are significantly lower than doses used therapeutically in infants from birth.

Information on infant plasma levels is not available.

No side effects have been reported in breastfed infants.

Verapamil

Rate-limiting calcium-channel blocker of choice

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Preferred choice

This is a preferred choice due to negligible amounts in breastmilk.

Infant monitoring

As a precaution, monitor the infant for hypotension which may manifest as drowsiness, lethargy, looking pale, poor feeding and inadequate weight gain.

Further information

Published case reports have shown variable levels of verapamil in breast milk, although amounts are still negligible. The 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.

Amlodipine

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Use with caution

Amlodipine is excreted into breast milk usually in very small amounts. It can be used with caution during breastfeeding, but nifedipine is the preferred dihydropyridine calcium-channel blocker.

Infant monitoring

As a precaution, monitor the infant for hypotension which may manifest as drowsiness, lethargy, looking pale , poor feeding and inadequate weight gain.

Further information

Published studies have shown variable levels of amlodipine in breast milk. On average they would result in the infant ingesting approximately 3 to 4% of the maternal weight-adjusted dose. However, at the highest level reported, the infant would have ingested 15.2% of the maternal weight-adjusted dose.

Compared to some other dihydropyridine calcium-channel blockers, amlodipine has less favourable pharmacokinetics. It has a very long half life and higher oral bioavailability, which increases the risk of drug absorption and accumulation in the infant.

However, in the published information to date, infant plasma levels were undetectable and no side effects have been reported in infants. Cases of normal growth and development have been reported in infants exposed to amlodipine through breast milk.

Diltiazem

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Use with caution

Diltiazem is excreted into breast milk in negligible amounts. It can be used with caution during breastfeeding, but if a rate-limiting calcium-channel blocker is required, verapamil is preferred.

Infant monitoring

As a precaution, monitor the infant for hypotension which may manifest as drowsiness, lethargy, looking pale, poor feeding and inadequate weight gain.

Further information

There is very little information on its excretion into breast milk but data suggest negligible amounts. In a single case report peak milk levels were 230micrograms/L which would equate to the infant ingesting 0.9% of the weight-adjusted maternal daily dose.

Information on infant plasma levels is not available.

No side effects have been reported in breastfed infants.

Felodipine

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Use with caution

There are no data on excretion of felodipine into breast milk. It can be used with caution during breastfeeding, but nifedipine is the preferred dihydropyridine calcium-channel blocker.

Infant monitoring

As a precaution, monitor the infant for hypotension which may manifest as drowsiness, lethargy, looking pale, poor feeding and inadequate weight gain.

Further information

There is no information on excretion of felodipine into breast milk although the manufacturers state that it has been detected in breast milk.

Levels in milk are expected to be low due to its high protein binding. The infant would also not be expected to absorb much from the milk due to its low oral bioavailability. However its long half-life and lack of data make it a less favourable choice.

No side effects have been reported in breastfed infants.

Patient Information

The NHS website provides advice for patients on the use of specific calcium-channel blockers in breastfeeding.

Contact us

Get in touch with the UK Drugs In Lactation Advisory Service (UKDILAS), our specialist breastfeeding medicines advice service if you need support in the following situations:

you need further advice
the medicine in question is not included in our advice
the infant is unwell or premature
multiple medicines are being taken

About our recommendations

Recommendations are based on published evidence where available. However, evidence is generally very poor and limited, and can require professional interpretation. Assessments are often based on reviewing case reports which can be conflicting and lack detail.

If there is no published clinical evidence, assessments are based on: pharmacodynamic and pharmacokinetic principles, extrapolation from similar drugs, risk assessment of normal clinical use, expert advice, and unpublished data. Simulated data are now increasingly being used due to the ethical difficulties around gathering good quality evidence in this area.

Bibliography

Full referencing is available on request.

SPS - Specialist Pharmacy Service

NHS

Using calcium-channel blockers during breastfeeding

Contents

General considerations

Recommendation

Choice considerations

Specific recommendations

Nifedipine

Preferred choice

Infant monitoring

Further information

Verapamil

Preferred choice

Infant monitoring

Further information

Amlodipine

Use with caution

Infant monitoring

Further information

Diltiazem

Use with caution

Infant monitoring

Further information

Felodipine

Use with caution

Infant monitoring

Further information

Patient Information

Contact us

About our recommendations

Bibliography

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