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Drugs, Supplies and Delivery
Nifedipine
Nifedipine is a widely used calcium channel blocker (CCB) that has been a cornerstone in the management of hypertension and angina for decades. As a dihydropyridine CCB, it primarily acts on vascular smooth muscle, making it particularly effective in reducing blood pressure. This article synthesizes information from the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology to provide a detailed overview of nifedipine, including its mechanism, uses, dosing, side effects, precautions, and drug interactions
Nifedipine blocks L-type voltage-gated calcium channels in vascular smooth muscle and cardiac muscle. By inhibiting calcium influx, it prevents smooth muscle contraction, leading to vasodilation of peripheral and coronary arteries. This results in:
- Reduced systemic vascular resistance, lowering blood pressure.
- Increased coronary blood flow, relieving angina symptoms (Lippincott, Lange).
Unlike non-dihydropyridine CCBs (e.g., verapamil, diltiazem), nifedipine has minimal effects on cardiac conduction and contractility, making it a safer option for patients with heart failure or conduction disorders (BNF).
- Hypertension: Nifedipine is a first-line antihypertensive, particularly effective in elderly patients and those with isolated systolic hypertension (BNF).
- Chronic Stable Angina: Used to prevent and treat angina by improving coronary blood flow and reducing myocardial oxygen demand (Lippincott).
- Raynaud’s Phenomenon: Helps relieve vasospasm in peripheral arteries (Lange).
- Preterm Labor (Off-Label): Sometimes used to suppress premature uterine contractions (Lippincott).
- Hypertension:
- Immediate-release (IR): 5–20 mg twice daily (max 40 mg/day).
- Extended-release (ER): 30–60 mg once daily (max 90 mg/day).
- Angina:
- Immediate-release: 5–20 mg three times daily.
- Extended-release: 30–60 mg once daily.
- Raynaud’s Phenomenon: 5–20 mg three times daily (BNF).
Administration:
- Immediate-release tablets should be swallowed whole with water.
- Extended-release formulations must not be crushed or chewed to avoid rapid absorption and potential toxicity (Lippincott).
- Common: Peripheral edema (due to arteriolar dilation), headache, flushing, dizziness, and palpitations (Lange).
- Serious: Hypotension, reflex tachycardia (especially with immediate-release formulations), and gingival hyperplasia (BNF).
- Hypotension: Use with caution in patients with severe hypotension or cardiogenic shock.
- Heart Failure: Avoid in patients with severe heart failure due to risk of worsening symptoms (Lippincott).
- Hepatic Impairment: Dose reduction may be necessary in patients with liver dysfunction (BNF).
- Pregnancy: Generally safe but should be used under medical supervision (Lange).
- Beta-Blockers: May exacerbate hypotension and heart failure; monitor closely.
- CYP3A4 Inhibitors (e.g., ketoconazole, erythromycin): Increase nifedipine levels, raising the risk of toxicity (Lippincott).
- Grapefruit Juice: Inhibits CYP3A4, increasing nifedipine bioavailability and risk of side effects (BNF).
- Rifampin: Reduces nifedipine levels, decreasing efficacy (Lange).
Nifedipine is the generic name for this medication. It is marketed under various brand names, including Adalat®, Procardia®, and Nifedical®. Generic versions are widely available, making it an affordable option for patients.
