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

Amlodipine Use During Pregnancy

Amlodipine is not recommended as a first-line antihypertensive medication during pregnancy, but can be considered a second-line option when first-line agents (labetalol and extended-release nifedipine) are contraindicated or poorly tolerated. 1

Safety Profile of Amlodipine in Pregnancy

First Trimester Exposure

• Limited data suggests amlodipine does not appear to be teratogenic when used in early pregnancy
• A study of 48 neonates exposed to amlodipine in the first trimester found no significant difference in birth defects compared to those exposed to other antihypertensives or no antihypertensives (4.2% vs 5.6% vs 4.7%) 2
• Amlodipine is classified as Category C, indicating potential benefits may justify potential risks 3

Placental Transfer and Breastfeeding

• Amlodipine does cross the placenta in measurable quantities (mean cord blood concentration 0.49 ng/mL compared to maternal serum level of 1.27 ng/mL) 4
• However, amlodipine is not detected in breast milk or infant plasma at 24-48 hours of life, suggesting it is likely safe during the postpartum period and breastfeeding 4

Recommended Antihypertensive Medications During Pregnancy

First-Line Agents

• Extended-release nifedipine (calcium channel blocker)
• Labetalol (alpha and beta-blocker) 1

Second-Line Agents

• Methyldopa (centrally acting alpha-2 agonist) - the only medication with long-term information on infant outcomes 1
• Amlodipine may be considered when first-line agents are not suitable

Contraindicated Agents

• ACE inhibitors and Angiotensin II receptor blockers (ARBs) - associated with renal dysplasia, oligohydramnios, and growth retardation 3
• Atenolol - associated with fetal growth restriction 1

Comparative Efficacy and Safety

• A meta-analysis found amlodipine's efficacy is slightly superior to nifedipine for treating hypertension during pregnancy (RR 1.06,95% CI 1.01 to 1.10) 5
• Amlodipine was associated with decreased risk for maternal side effects compared to nifedipine (RR 0.42,95% CI 0.29 to 0.61) 5
• Amlodipine achieved better control of systolic and diastolic blood pressure compared with intermediate/long-acting nifedipine 5

Postpartum Considerations

• Amlodipine is considered a first-line agent for postpartum hypertension regardless of breastfeeding status 1
• Advantages include once-daily dosing and alignment with general hypertension guidelines 1

Clinical Approach to Antihypertensive Selection in Pregnancy

1. First-line options: Start with extended-release nifedipine or labetalol
2. If first-line agents are not tolerated or contraindicated:
   • Consider methyldopa (especially in low-resource settings)
   • Consider amlodipine as an alternative calcium channel blocker
3. Never use: ACE inhibitors, ARBs, or atenolol during pregnancy

Important Caveats

• Always weigh the potential risk of medication against the possible benefit of treating maternal hypertension 3
• Untreated severe hypertension during pregnancy poses significant risks to both mother and fetus
• The timing of drug exposure during pregnancy is critical, with first trimester exposure often carrying the highest risk for structural malformations 3
• Medication selection should consider the severity of hypertension, maternal comorbidities, and gestational age