Is amlodipine (calcium channel blocker) safe to use during pregnancy?

Safety of Amlodipine During Pregnancy

Amlodipine is not recommended as a first-line antihypertensive medication during pregnancy, although it does not appear to be teratogenic based on limited data. 1

Evidence on Amlodipine Use in Pregnancy

The FDA drug label for amlodipine provides limited information regarding its use during pregnancy:

• There is insufficient data from post-marketing reports to determine drug-associated risk for major birth defects and miscarriage 1
• Animal studies showed no evidence of adverse developmental effects at doses 10-20 times the maximum recommended human dose 1
• However, in animal studies, litter size was decreased by about 50% and intrauterine deaths increased about 5-fold 1

Recommended Antihypertensive Medications in Pregnancy

Current guidelines recommend specific antihypertensive medications during pregnancy:

• First-line agents:

  • Extended-release nifedipine (preferred calcium channel blocker)
  • Labetalol
  • Methyldopa (although less commonly used in high-income countries) 2

• Second-line agents can be used in addition to first-line agents or as alternatives in cases of allergies, intolerances, or contraindications 2

Postpartum Considerations

After delivery, amlodipine is considered safe and is actually recommended as a first-line agent:

• First-line agents for postpartum hypertension include amlodipine, nifedipine, enalapril, and labetalol 2, 3
• Advantages of amlodipine include once-daily dosing and alignment with general hypertension guidelines 2
• Amlodipine is present in breast milk at an estimated median relative infant dose of 4.2%, but no adverse effects on breastfed infants have been observed 1, 4

Clinical Research Evidence

Limited studies have evaluated amlodipine during pregnancy:

• A 2022 meta-analysis comparing amlodipine to nifedipine for hypertension during pregnancy found amlodipine slightly superior in efficacy with decreased maternal side effects 5
• A pharmacokinetic study showed amlodipine does cross the placenta in measurable quantities but was not detected in breast milk or infant plasma at 24-48 hours of life 4
• Case reports have not identified teratogenic effects, but data remains limited 6

Contraindicated Medications in Pregnancy

It's important to note that certain antihypertensive medications are explicitly contraindicated during pregnancy:

• ACE inhibitors and angiotensin receptor blockers are contraindicated due to risk of fetal renal dysplasia, oligohydramnios, pulmonary hypoplasia, and intrauterine growth restriction 2
• Atenolol is not recommended due to risk of fetal growth restriction 2

Clinical Recommendation

For pregnant women requiring antihypertensive therapy:

1. Use extended-release nifedipine or labetalol as first-line agents
2. Reserve amlodipine for situations where first-line agents cannot be used
3. After delivery, amlodipine is an appropriate first-line agent for postpartum hypertension management
4. Breastfeeding appears to be safe while taking amlodipine

Blood Pressure Targets

For pregnant women with hypertension, guidelines recommend:

• Initiate treatment at BP ≥140/90 mmHg 2
• Target BP below 140/90 mmHg but not below 80 mmHg for diastolic BP 2
• A suggested range of 110-135/85 mmHg is reasonable to reduce risk of accelerated maternal hypertension while minimizing impaired fetal growth 2

While amlodipine may be used in certain circumstances during pregnancy, the established safety profile of extended-release nifedipine and labetalol makes them preferred first-line options for managing hypertension in pregnant women.