Nifedipine: Drug Profile

What is Nifedipine?

Nifedipine is a prescription medication that belongs to a class of drugs called calcium channel blockers, specifically the dihydropyridine type. It is primarily used to treat high blood pressure (hypertension) and certain types of chest pain (angina) by relaxing and widening blood vessels. The medication is available in both immediate-release and extended-release formulations.

Uses

Nifedipine is approved for several cardiovascular conditions:

• Hypertension: The most common use, helping to lower blood pressure and reduce the risk of heart attack, stroke, and kidney problems
• Chronic stable angina: Prevents chest pain episodes in patients with coronary artery disease by improving blood flow to the heart muscle
• Vasospastic angina: Treats chest pain caused by spasms in the coronary arteries (also called Prinzmetal’s or variant angina)
• Raynaud’s phenomenon: Sometimes prescribed off-label to improve circulation in fingers and toes affected by this condition
• Preterm labor: Occasionally used in hospital settings to help delay premature contractions, though this is not a primary indication

How it works

Nifedipine works by blocking calcium channels in the smooth muscle cells of blood vessels and the heart. By preventing calcium from entering these cells, the medication causes blood vessels to relax and dilate, which reduces blood pressure and improves blood flow. This mechanism also reduces the workload on the heart and decreases oxygen demand, making it effective for treating angina.

Side effects

Common side effects include:

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• Swelling of ankles, feet, or hands (peripheral edema)
• Flushing or feeling warm
• Headache
• Dizziness or lightheadedness
• Fatigue or weakness
• Nausea
• Constipation
• Muscle cramps

Serious side effects requiring immediate medical attention:

• Severe drop in blood pressure causing fainting
• Rapid or irregular heartbeat
• Chest pain or worsening angina
• Severe swelling or difficulty breathing
• Signs of liver problems (yellowing of skin or eyes, dark urine)

Warnings and precautions

• Heart conditions: Patients with severe heart failure, aortic stenosis, or recent heart attack should use nifedipine with extreme caution or avoid it entirely
• Pregnancy and breastfeeding: Classified as pregnancy category C; should only be used when benefits outweigh risks, and caution is advised during breastfeeding
• Liver impairment: Patients with liver disease may need dose adjustments as the drug is metabolized by the liver
• Sudden discontinuation: Should not be stopped abruptly as this may cause rebound hypertension or worsening angina
• Grapefruit interaction: Grapefruit and grapefruit juice can significantly increase nifedipine levels and should be avoided

Interactions

Nifedipine has several important drug interactions:

• Beta-blockers: May cause excessive blood pressure lowering or heart rate reduction when combined
• Digoxin: Nifedipine can increase digoxin levels, potentially leading to toxicity
• Rifampin: This antibiotic can reduce nifedipine effectiveness by increasing its breakdown
• Cimetidine: May increase nifedipine levels by slowing its metabolism
• Phenytoin: Can reduce nifedipine levels and effectiveness
• Quinidine: May have reduced effectiveness when taken with nifedipine
• St. John’s Wort: This herbal supplement can decrease nifedipine levels
• Alcohol: Can enhance the blood pressure-lowering effects and increase dizziness

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Dosage

Nifedipine dosage varies depending on the condition being treated and the formulation used. For immediate-release capsules, typical starting doses range from 10-20 mg three times daily, with maintenance doses usually between 10-30 mg three to four times daily. Extended-release tablets typically start at 30-60 mg once daily, with maintenance doses ranging from 30-90 mg once daily. Maximum daily doses generally do not exceed 180 mg. Elderly patients and those with liver impairment often require lower starting doses. Dosage should always be individualized and determined by a healthcare provider based on the patient’s specific condition, response to treatment, and other medications being taken.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

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