Nifedipine as a Calcium Channel Blocker
Yes, nifedipine is definitively a calcium channel blocker, specifically a dihydropyridine calcium channel blocker that inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. 1
Pharmacological Classification and Mechanism
- Nifedipine belongs to the dihydropyridine subclass of calcium channel blockers, one of three chemically distinct subclasses (the others being benzothiazepines like diltiazem and phenylalkylamines like verapamil) 2
- It works by selectively inhibiting calcium ion influx across cell membranes of vascular smooth muscle and cardiac muscle without altering serum calcium concentrations 1
- Nifedipine binds to voltage-dependent and possibly receptor-operated channels in vascular smooth muscle, resulting in inhibition of calcium influx through these channels 1
Pharmacodynamic Effects
- As a calcium channel blocker, nifedipine causes peripheral arterial vasodilation, making it effective for treating hypertension and angina 3
- Among calcium channel blockers, nifedipine produces the most marked peripheral arterial vasodilation compared to other agents in its class 2
- The reduction in calcium influx by nifedipine causes arterial vasodilation and decreased peripheral vascular resistance, which results in reduced arterial blood pressure 1, 4
Clinical Applications
- Nifedipine is primarily used for the management of:
Important Clinical Considerations
- Nifedipine or other dihydropyridines should not be used without concomitant beta-blocker therapy in coronary artery disease due to potential increased cardiovascular risk 2
- Several analyses suggest that short-acting nifedipine might be associated with a dose-dependent detrimental effect on mortality in patients with coronary artery disease 2
- In acute coronary syndromes, there was a trend toward increased risk of myocardial infarction or recurrent angina with nifedipine compared to placebo in the HINT study 2
Pharmacokinetics
- Nifedipine is completely absorbed after oral administration 1
- Extended-release formulations have an elimination half-life of approximately 7 hours compared to 2 hours for immediate-release formulations 1
- Once-daily dosing of extended-release nifedipine results in decreased fluctuations in plasma concentration compared to multiple daily dosing with immediate-release formulations 1
Unique Properties Among Calcium Channel Blockers
- Unlike non-dihydropyridine calcium channel blockers (verapamil and diltiazem), nifedipine has minimal direct effects on atrioventricular conduction and heart rate 2, 7
- Nifedipine may also facilitate neurotransmitter release through a mechanism independent of its calcium channel blocking effects, which may explain some of its side effects 8