Felodipine

What is Felodipine?

Felodipine is a prescription medication that belongs to a class of drugs called calcium channel blockers, specifically the dihydropyridine subclass. It is primarily used to treat high blood pressure (hypertension) and certain heart conditions by relaxing blood vessels and improving blood flow. This medication is typically taken as an extended-release tablet once daily.

Uses

• Hypertension (High Blood Pressure): The primary use of felodipine is to lower blood pressure in adults, helping to reduce the risk of heart attack, stroke, and kidney problems.
• Chronic Stable Angina: Used to prevent chest pain episodes caused by reduced blood flow to the heart muscle, particularly in patients who cannot tolerate beta-blockers.
• Coronary Artery Disease: May be prescribed as part of a comprehensive treatment plan to improve blood flow to the heart in patients with narrowed coronary arteries.
• Raynaud’s Phenomenon: Sometimes used off-label to improve circulation in fingers and toes by reducing blood vessel spasms in this condition.
• Combination Therapy: Often used alongside other blood pressure medications such as ACE inhibitors or diuretics when single-drug therapy is insufficient.

How it works

Felodipine works by blocking calcium channels in the smooth muscle cells of blood vessel walls, preventing calcium from entering these cells. When calcium is blocked, the blood vessels relax and widen (vasodilation), which reduces blood pressure and increases blood flow to the heart and other organs. This mechanism also reduces the workload on the heart, making it easier for the heart to pump blood effectively.

Side effects

Common side effects:

• Ankle and foot swelling (peripheral edema)
• Dizziness or lightheadedness
• Headache
• Flushing or warmth in face and neck
• Fatigue or weakness
• Rapid heartbeat (palpitations)
• Nausea
• Gum swelling or tenderness

Serious side effects requiring immediate medical attention:

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• Severe drop in blood pressure with fainting
• Chest pain or worsening angina
• Severe swelling of face, lips, tongue, or throat
• Irregular or very fast heartbeat
• 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 felodipine with caution as it may worsen these conditions.
• Liver Disease: Individuals with liver problems may need dose adjustments since felodipine is primarily metabolized by the liver.
• Pregnancy and Breastfeeding: Felodipine is classified as pregnancy category C; it should only be used during pregnancy if benefits outweigh risks. The drug may pass into breast milk.
• Elderly Patients: Older adults may be more sensitive to the blood pressure-lowering effects and may require lower starting doses.
• Sudden Discontinuation: Do not stop taking felodipine abruptly without consulting a healthcare provider, as this may cause rebound high blood pressure or worsening angina.

Interactions

• Grapefruit and Grapefruit Juice: Can significantly increase felodipine blood levels, leading to dangerous drops in blood pressure.
• CYP3A4 Inhibitors (ketoconazole, erythromycin, cimetidine): These medications can increase felodipine levels and enhance its blood pressure-lowering effects.
• Beta-blockers (metoprolol, propranolol): May enhance the blood pressure-lowering effect, requiring careful monitoring.
• Digoxin: Felodipine may increase digoxin levels in the blood, potentially leading to toxicity.
• Phenytoin and Carbamazepine: These anti-seizure medications may reduce felodipine effectiveness by increasing its metabolism.
• Other Blood Pressure Medications: Combining with other antihypertensives may cause excessive blood pressure reduction.
• NSAIDs (ibuprofen, naproxen): May reduce the blood pressure-lowering effects of felodipine.
• St. John’s Wort: This herbal supplement may decrease felodipine effectiveness by increasing its breakdown in the liver.

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Dosage

Adult Hypertension: The typical starting dose is 5 mg once daily, which may be increased to 10 mg once daily based on blood pressure response. The maximum recommended dose is 20 mg daily. Elderly patients or those with liver impairment: Usually start with 2.5 mg once daily. Felodipine extended-release tablets should be swallowed whole and not crushed, chewed, or split. The medication can be taken with or without food, but should be taken consistently. All dosage adjustments should be made gradually over 1-2 weeks and determined by a healthcare provider based on individual patient response and tolerance.

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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