Nifedipine

Drug Overview

Nifedipine is a common calcium channel blocker primarily used to treat hypertension (primary hypertension) and angina pectoris (myocardial ischemia). This medication selectively inhibits calcium entry into vascular smooth muscle cells, causing vasodilation, reducing peripheral vascular resistance, and thereby lowering blood pressure and improving coronary blood flow.

Its mechanism of action differs from other classes of antihypertensive drugs, making it particularly suitable for patients who respond poorly to beta-blockers or diuretics. Additionally, nifedipine is used to treat peripheral arterial disease, alleviating pain or numbness caused by limb ischemia.

Brand Names and Generic Name

The generic name of this drug is Nifedipine. Common brand names include:

• Adalat
• Procardia
• Nifediac

Drug Classification

Nifedipine belongs to the class of "Dihydropyridine Calcium Channel Blockers." This class is characterized by selective action on vascular smooth muscle, with minimal effects on myocardial contractility and heart rate. Compared to non-dihydropyridines (such as diltiazem), it has a more pronounced vasodilatory effect but may cause more peripheral side effects.

Indications

Main Indications:

• Primary hypertension
• Stable angina pectoris

Other Uses:

• Peripheral arterial occlusive disease (intermittent claudication)
• In certain cases, used to control hypertension caused by eclampsia

Common Side Effects

Mild Side Effects:

• Lower limb edema (swelling of the feet)
• Dizziness or headache
• Facial flushing or skin itching

Serious Side Effects (Seek immediate medical attention):

• Palpitations or irregular heartbeat
• Shortness of breath or worsening chest pain
• Fainting or altered consciousness

Warnings and Precautions

Contraindications:

• Allergy to nifedipine or its components
• Severe heart failure or cardiomegaly requires caution
• Severe aortic stenosis should avoid use

Pregnancy and Breastfeeding:

• The FDA pregnancy category is C; use during pregnancy should be evaluated by a physician for risks
• The drug may be secreted into breast milk; breastfeeding women should use under medical supervision

Drug Interactions

Nifedipine may interact with the following medications:

• Beta-blockers (e.g., metoprolol): may enhance hypotension or bradycardia
• Statins (e.g., atorvastatin): may increase risk of muscle side effects
• Immunosuppressants (e.g., cyclosporine): may exacerbate hypotension

Consult a physician before taking herbal medicines or supplements (such as ginkgo biloba extract) to avoid affecting blood pressure control. Taking with grapefruit juice may increase blood drug levels; it is recommended to avoid consumption.

Dosage and Administration

Dosage should be adjusted based on the condition:

• Hypertension: typically 20-40 mg daily in divided doses; sustained-release formulations may be taken once daily
• Angina: initial dose 5-10 mg every 6-8 hours

Swallow whole; do not chew or split tablets. Can be taken with or without food, but should be taken at the same time each day to maintain stable blood levels. Sustained-release formulations should not be crushed or dissolved, as this may cause excessive blood pressure reduction.

Missed Dose Management

If a dose is missed, take it as soon as remembered. If it is close to the next scheduled dose, skip the missed dose and resume the regular schedule. Do not double doses to make up for a missed one, to avoid severe reactions such as hypotension.

Overdose Management

Overdose may lead to severe hypotension, tachycardia, or syncope. If these symptoms occur, seek immediate medical attention and bring the medication packaging for reference. Emergency measures may include plasma volume expansion, vasopressors, or cardiac monitoring.

 

Frequently Asked Questions

When taking nifedipine, should I pay special attention to meal timing or content?

It is recommended to take nifedipine at a fixed time to maintain consistent drug effects. Different formulations (such as regular tablets or sustained-release) may have specific instructions; follow your doctor’s advice. Food intake can affect the absorption of regular tablets; it is advised to take on an empty stomach or 2 hours after meals. Sustained-release formulations can usually be taken with food. Avoid high-fat meals to reduce gastrointestinal discomfort.

What should I do if I experience lower limb edema while taking nifedipine?

Some patients may develop ankle or calf swelling due to vasodilation. Elevating the legs, reducing standing time, and eating a low-salt diet may help reduce swelling. If swelling significantly affects daily life, consult a doctor for dose adjustment or medication change. Do not stop medication on your own.

What should I watch out for when using nifedipine with lipid-lowering drugs (e.g., statins)?

Combined use may increase the risk of muscle pain or weakness. Regular monitoring of creatine phosphokinase (CPK) levels is recommended. The doctor will adjust doses based on liver function and overall health. If unexplained muscle pain or dark urine occurs, stop medication and seek medical attention immediately.

What are the risks of suddenly stopping nifedipine?

Sudden discontinuation may cause a rebound phenomenon, leading to a rapid increase in blood pressure and increasing the risk of cardiovascular events. If medication adjustment is needed, the doctor will gradually reduce the dose and evaluate alternatives. Always discuss with your healthcare provider before stopping medication to avoid self-decisions.

Is a sudden drop in blood pressure during exercise related to nifedipine?

This medication may cause orthostatic hypotension due to vasodilation. It is recommended to rest for 15 minutes before exercising and avoid exercising on an empty stomach. Start with low-intensity exercise and gradually increase. If dizziness or weakness occurs during exercise, stop immediately and measure blood pressure. Consult your doctor for timing or dosage adjustments if necessary.