What is the mechanism of action of Procardia (Nifedipine) in pregnancy?

From the Guidelines

Procardia (nifedipine) works in pregnancy by blocking calcium channels in smooth muscle cells, primarily in blood vessels, leading to relaxation of vascular smooth muscle and uterine muscle, which reduces blood pressure and inhibits uterine contractions. When used for conditions like preterm labor or hypertension in pregnancy, nifedipine prevents calcium from entering these cells, causing blood vessel dilation and reducing blood pressure 1.

Key Points

• For preterm labor, immediate-release nifedipine is typically given as a 10-20 mg loading dose followed by 10-20 mg every 4-6 hours, while for hypertension in pregnancy, extended-release formulations of 30-60 mg daily are often used 1.
• Nifedipine crosses the placenta but has been used safely in pregnancy with minimal adverse effects on the fetus 1.
• It's essential to monitor blood pressure closely during administration as rapid drops in maternal blood pressure can affect placental perfusion 1.
• Side effects may include headache, flushing, dizziness, and peripheral edema 1.
• Nifedipine should not be given sublingually for rapid effect in pregnancy due to risks of precipitous hypotension 1.

Recommendations

• Labetalol and oral nifedipine are currently suggested as first-line treatment for hypertensive emergencies during pregnancy 1.
• Methyldopa should not be used primarily for urgent BP reduction 1.
• Magnesium sulfate is recommended for the prevention of eclampsia and treatment of seizures but should not be given concomitantly with calcium channel blockers (risk of hypotension due to potential synergism) 1.

From the FDA Drug Label

Nifedipine is a calcium ion influx inhibitor (slow-channel blocker or calcium ion antagonist) which inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. The mechanism by which nifedipine reduces arterial blood pressure involves peripheral arterial vasodilatation and, consequently, a reduction in peripheral vascular resistance The binding of nifedipine to voltage-dependent and possibly receptor-operated channels in vascular smooth muscle results in an inhibition of calcium influx through these channels.

The mechanism of action of nifedipine (Procardia) in pregnancy is not directly addressed in the provided drug label. However, based on the available information, the mechanism of action of nifedipine in general involves:

• Calcium channel blockade: inhibiting the influx of calcium ions into vascular smooth muscle and cardiac muscle
• Peripheral arterial vasodilation: reducing peripheral vascular resistance and consequently lowering arterial blood pressure
• Inhibition of calcium influx: binding to voltage-dependent and possibly receptor-operated channels in vascular smooth muscle, resulting in decreased calcium influx and vasodilation 2

From the Research

Mechanism of Action of Procardia in Pregnancy

Procardia, also known as nifedipine, is a calcium channel blocker used to treat severe hypertension in pregnancy. The mechanism of action of nifedipine involves the relaxation of vascular smooth muscle, leading to a decrease in blood pressure 3, 4, 5.

Efficacy of Nifedipine in Pregnancy

Studies have shown that nifedipine is effective in reducing blood pressure in pregnant women with severe hypertension. A systematic review and network meta-analysis found that nifedipine was superior to hydralazine in achieving successful treatment of severe hypertension, but not significantly different from labetalol 5. Another study found that nifedipine achieved treatment success in most women, similar to hydralazine and labetalol 4.

Comparison with Other Antihypertensive Agents

Nifedipine has been compared to other antihypertensive agents, including labetalol and methyldopa, in the treatment of severe hypertension in pregnancy. A randomized controlled trial found that nifedipine was more effective than methyldopa in achieving blood pressure control, but not significantly different from labetalol 3. Another study found that labetalol was the most frequently used medication, followed by nifedipine and hydralazine, in a real-world cohort of patients with hypertensive disorders of pregnancy 6.

Safety and Maternal Outcomes

The safety of nifedipine in pregnancy has been evaluated in several studies. A systematic review and network meta-analysis found that nifedipine was not associated with an increased risk of caesarean delivery or maternal side effects 5. Another study found that antihypertensive drug therapy, including nifedipine, was advisable in mild to moderate chronic hypertension during pregnancy to decrease maternal and fetal morbidity 7.

Key Findings

• Nifedipine is a calcium channel blocker used to treat severe hypertension in pregnancy.
• Nifedipine is effective in reducing blood pressure in pregnant women with severe hypertension.
• Nifedipine has been compared to other antihypertensive agents, including labetalol and methyldopa, in the treatment of severe hypertension in pregnancy.
• The safety of nifedipine in pregnancy has been evaluated, and it is not associated with an increased risk of caesarean delivery or maternal side effects.
• Antihypertensive drug therapy, including nifedipine, is advisable in mild to moderate chronic hypertension during pregnancy to decrease maternal and fetal morbidity 3, 4, 6, 5, 7.