Nifedipine L.P. Viatris (Nifedipine)

• Nifedipine is a calcium channel blocker used to manage cardiovascular conditions that involve vascular tone and myocardial oxygen demand.
• Hypertension: reduces peripheral vascular resistance, leading to a sustained decrease in systolic and diastolic blood pressure in patients with essential hypertension.
• Chronic stable angina: improves coronary blood flow and reduces myocardial oxygen demand, thereby relieving exertional chest pain and increasing exercise tolerance.
• Raynaud's phenomenon: induces vasodilation in peripheral arteries, decreasing the frequency and severity of ischemic attacks in patients with primary or secondary Raynaud's phenomenon.

• Nifedipine selectively blocks L‑type calcium channels in vascular smooth muscle and cardiac myocytes. By inhibiting calcium influx, it prevents contraction of arterial smooth muscle, producing dose‑dependent vasodilation of peripheral arteries and coronary vessels. The resulting fall in systemic vascular resistance lowers arterial pressure, while coronary vasodilation improves myocardial oxygen delivery. Its action is rapid and reversible, reflecting its high affinity for the dihydropyridine binding site on the channel protein.

Nifedipine may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Headache: mild to moderate headache often occurring at treatment initiation.
• Flushing: transient warmth and redness of the face or neck.
• Peripheral edema: swelling of the ankles or lower legs.
• Dizziness: light‑headedness, especially when standing quickly.
• Nausea: mild gastrointestinal upset.

Serious or Rare Side Effects

• Severe hypotension: marked drop in blood pressure that may cause fainting.
• Myocardial infarction: rare occurrence of heart attack, particularly in patients with pre‑existing coronary disease.
• Atrioventricular block: conduction disturbances requiring medical attention.
• Hepatotoxicity: abnormal liver function tests or liver injury.
• Allergic reactions: rash, itching, or anaphylaxis in susceptible individuals.

Before prescribing nifedipine, clinicians should consider several precautionary measures to ensure safe use.

• Cardiovascular assessment: evaluate for severe aortic stenosis or unstable heart failure before initiating therapy.
• Concomitant antihypertensives: monitor blood pressure closely when combined with other blood‑pressure‑lowering agents.
• Liver impairment: adjust therapy in patients with moderate to severe hepatic dysfunction.
• Grapefruit products: avoid consumption as they can increase nifedipine plasma concentrations.
• Pregnancy and lactation: use only if the potential benefit justifies the potential risk to the fetus or infant.
• Store at ambient temperature: keep below 25 °C in the original packaging, protected from moisture and light.

Nifedipine can interact with other medicines, altering its effectiveness or increasing the risk of adverse events.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors: such as ketoconazole, itraconazole, or ritonavir, which can markedly raise nifedipine levels.
• Simultaneous use with other calcium channel blockers: may cause excessive vasodilation and hypotension.
• Grapefruit juice: potent inhibitor of CYP3A4 leading to increased plasma concentrations.

Moderate Interactions (Monitor Closely)

• Beta‑blockers: combined therapy may enhance blood‑pressure lowering effect.
• Diuretics: may increase risk of orthostatic hypotension.
• Digoxin: nifedipine can raise digoxin levels, requiring serum monitoring.