From the Guidelines
Nifedipine, a calcium channel blocker, has a primary effect of reducing peripheral arterial resistance, leading to vasodilation, which can help decrease myocardial oxygen demand and improve myocardial flow.
Key Effects of Nifedipine
- Vasodilation: Nifedipine has the most peripheral arterial dilatory effects among calcium channel blockers, which helps in reducing blood pressure and decreasing the workload on the heart 1.
- Decreased Myocardial Oxygen Demand: By reducing afterload and contractility, nifedipine can decrease the heart's oxygen demand, which is beneficial in conditions like unstable angina or non-ST-elevation myocardial infarction (UA/NSTEMI) 1.
- Improved Myocardial Flow: Nifedipine's ability to cause coronary arterial and arteriolar dilation can improve blood flow to the myocardium, further aiding in the management of ischemic conditions 1.
Important Considerations
- Concomitant Beta Blockade: It is crucial to use nifedipine with concomitant beta blockade in UA/NSTEMI to avoid increased adverse potential, such as reflex tachycardia that could worsen myocardial ischemia 1.
- Side Effects: Common side effects of nifedipine include hypotension, dizziness, flushing, nausea, constipation, and edema. Monitoring for these side effects is essential, especially in patients with certain comorbidities or those taking other medications that could interact with nifedipine 1.
- Dosage: The usual dose of nifedipine is between 30 to 90 mg daily orally for the immediate release form and 30 to 180 mg orally for the slow release form. The choice of dosage form and the specific dose should be tailored to the individual patient's needs and response to therapy 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 reduction in calcium influx by nifedipine causes arterial vasodilation and decreased peripheral vascular resistance which results in reduced arterial blood pressure.
The effect of Nifedipine is to:
- Inhibit calcium ion influx into vascular smooth muscle and cardiac muscle
- Cause peripheral arterial vasodilatation
- Reduce peripheral vascular resistance
- Lower arterial blood pressure This is based on the information provided in the drug label 2.
From the Research
Effects of Nifedipine on Blood Pressure
- Nifedipine is a dihydropyridine calcium-channel blocker that lowers blood pressure and improves symptoms of angina 3
- The drug has a rapid onset of action, with a mean arterial pressure reduction of 21.6% 4
- Nifedipine can be administered buccally to rapidly treat moderately severe hypertension, with a drop in blood pressure from 205.5 +/- 24.4/127.7 +/- 11.7 mm Hg to 158.6 +/- 24.7/88.8 +/- 10 mm Hg in 39.9 +/- 13.0 minutes 5
Effects of Nifedipine on Cardiovascular Events
- Several meta-analyses and a case-control study raised concern regarding increased mortality and increased risk for myocardial infarction with short-acting nifedipine 3
- However, a retrospective evaluation of the safety of nifedipine immediate release found a per-dose incidence of 2.4% and per-patient incidence of 7.3% in the composite endpoint of nifedipine-associated adverse events, with no differences between high- and low-risk groups 6
Mechanism of Action
- Nifedipine exerts its effect by calcium channel blockade and nitric oxide production 7
- However, nifedipine also facilitates neurotransmitter release independently of calcium channels, which may partially explain its side effects 7
- This effect is dose dependent, with an EC(50) of 7.8 microM, and is largely calcium-independent 7