Nifedipin

Nifedipin, also spelled nifedipine, is a calcium channel blocker in the dihydropyridine class. It is used to treat essential hypertension, chronic stable angina, and vasospastic (Prinzmetal) angina, and can be prescribed for certain vascular conditions such as Raynaud’s phenomenon.

Mechanism of action and effects: Nifedipin inhibits L-type calcium channels in vascular smooth muscle, leading to dilation of peripheral arteries and a reduction in systemic vascular resistance. This vasodilation lowers blood pressure and can relieve anginal symptoms. Reflex sympathetic activation may occur, potentially causing heart rate or contractility changes. The drug has relatively limited effects on cardiac conduction compared with non-dihydropyridine calcium channel blockers.

Forms and administration: Nifedipin is available in oral forms, including immediate-release and extended-release tablets. The short-acting, immediate-release formulations are associated with rapid blood pressure reductions and are generally avoided for routine hypertension management due to safety concerns; longer-acting formulations are preferred for most indications.

Pharmacokinetics: After oral dosing, nifedipin is well absorbed but undergoes extensive hepatic first-pass metabolism. It is primarily metabolized by the CYP3A4 enzyme system. The duration of action depends on the formulation, with extended-release forms providing Sustained effects over 24 hours in many patients.

Adverse effects and safety: Common side effects include edema (especially in the ankles and feet), headache, flushing, dizziness, palpitations, gingival hyperplasia, and hypotension. It should be used with caution in patients with heart failure with reduced ejection fraction, severe aortic stenosis, or significant hypotension. Drug interactions include other antihypertensives and CYP3A4 inhibitors or inducers; grapefruit juice can increase nifedipin levels.

History and regulation: Nifedipin has been widely used since the late 20th century and is available in various generic formulations alongside brand-name products.