Comprehensive Guide to Felodipine: Uses, Dosage, Side Effects, and More
What is Felodipine?
Overview of Felodipine
Generic Name: Felodipine
Brand Name: Plendil, generics
Drug Group: Calcium channel blocker (antihypertensive, antianginal)
Commonly Used For
- Treat hypertension (high blood pressure).
- Manage stable angina pectoris.
- Reduce cardiovascular risk in specific populations.
Key Characteristics
Form: Extended-release tablets (2.5 mg, 5 mg, 10 mg) (detailed in Dosage section).
Mechanism: Blocks L-type calcium channels, relaxing arterial smooth muscle.
Approval: FDA-approved (1991 for Plendil) and EMA-approved for hypertension and angina.
Indications and Uses of Felodipine
Felodipine is indicated for a variety of cardiovascular conditions, leveraging its vasodilatory effects:
Hypertension: Lowers blood pressure in essential hypertension, per cardiology guidelines, supported by clinical trials showing a 10–15 mmHg systolic reduction.
Stable Angina Pectoris: Reduces chest pain frequency and improves exercise tolerance, recommended in cardiovascular protocols with evidence of increased coronary perfusion.
Raynaud’s Phenomenon: Investigated off-label to alleviate vasospastic episodes, with rheumatology-cardiology data.
Congestive Heart Failure (Adjunct): Managed off-label with diuretics to reduce afterload, with heart failure research.
Preeclampsia (Off-Label): Explored in pregnant women to control severe hypertension, with obstetrics-cardiology studies.
Chronic Kidney Disease (CKD): Used off-label to manage hypertension in CKD patients, reducing proteinuria, per nephrology evidence.
Ischemic Heart Disease: Initiated off-label to improve myocardial oxygen supply, with cardiology research.
Migraine Prophylaxis: Investigated off-label for vascular headache prevention, with neurology data.
Peripheral Artery Disease (PAD): Applied off-label to enhance lower limb perfusion, with vascular surgery evidence.
Diabetic Nephropathy: Explored off-label to protect renal function, with endocrinology-nephrology studies.
Dosage of Felodipine
Dosage for Adults
Hypertension:
- Initial: 2.5–5 mg once daily, titrated to 5–10 mg after 1–2 weeks if needed, taken in the morning.
- Maximum: 10 mg daily.
Stable Angina Pectoris:
- Initial: 5 mg once daily, adjusted to 5–10 mg based on symptom control and tolerability.
- Maximum: 10 mg daily.
Dosage for Elderly (≥65 years)
Hypertension or Angina:
- Initial: 2.5 mg once daily, titrated cautiously to 5 mg, under geriatric cardiology supervision due to increased sensitivity.
Dosage for Pregnant Women
Pregnancy Category C: Use only if benefits outweigh risks; consult an obstetrician and cardiologist, with fetal monitoring.
Dosage Adjustments
Renal Impairment: No adjustment needed; monitor in severe cases (CrCl <30 mL/min).
Hepatic Impairment:
Mild to moderate (Child-Pugh A or B): Reduce initial dose to 2.5 mg; severe (Child-Pugh C): Avoid.
Concomitant Medications: Adjust if combined with beta-blockers or CYP3A4 inhibitors (e.g., grapefruit juice), increasing levels; monitor.
Elderly or Debilitated: Start with 2.5 mg; titrate slowly to avoid hypotension.
Combination Therapy: Use lower doses when combined with other antihypertensives (e.g., ACE inhibitors).
Additional Considerations
- Take this active ingredient with or without food, but avoid high-fat meals to prevent increased absorption.
- Swallow extended-release tablets whole; do not crush or chew.
- Monitor blood pressure 1–2 weeks after dose changes.
How to Use Felodipine
Administration:
Oral: Swallow extended-release tablets with a glass of water, preferably in the morning.
Take consistently at the same time daily to maintain steady levels.
Timing: Administer once daily, with or without food, avoiding grapefruit juice.
Monitoring: Watch for dizziness, swelling, or signs of hypotension (e.g., fainting); report changes immediately.
Additional Tips:
- Store at 20–25°C (68–77°F), protecting from moisture and light.
- Keep out of reach of children due to cardiovascular risk.
- Use a pill organizer for elderly patients to ensure adherence.
- Avoid sudden position changes (e.g., standing up quickly) to prevent orthostatic hypotension.
- Schedule regular blood pressure checks every 1–2 weeks during titration.
Contraindications for Felodipine
Hypersensitivity: Patients with a known allergy to Felodipine or other dihydropyridines.
Severe Aortic Stenosis: Contraindicated due to risk of hypotension and reduced cardiac output.
Acute Myocardial Infarction: Avoid within the first 2–4 weeks due to hemodynamic instability.
Unstable Angina: Contraindicated until stabilized, due to reflex tachycardia risk.
Severe Hypotension: Avoid in systolic blood pressure <90 mmHg.
Severe Hepatic Impairment: Contraindicated in Child-Pugh Class C due to metabolism concerns.
Warnings & Precautions for Felodipine
General Warnings
Hypotension: Risk of excessive blood pressure drop; monitor supine and standing BP.
Reflex Tachycardia: Risk of increased heart rate; assess pulse regularly.
Peripheral Edema: Common side effect; elevate legs if severe.
Liver Dysfunction: Risk of toxicity in hepatic impairment; check liver enzymes.
Heart Failure Worsening: Risk in decompensated heart failure; use cautiously.
Additional Warnings
Gingival Hyperplasia: Rare overgrowth of gums with long-term use; maintain oral hygiene.
Myocardial Ischemia: Risk if abruptly withdrawn; taper dose.
Renal Impairment: Risk of fluid retention; monitor renal function.
Hypersensitivity Reactions: Rare angioedema; discontinue if swelling occurs.
Electrolyte Imbalance: Risk with diuretics; monitor potassium and magnesium.
Use in Specific Populations
Pregnancy: Category C; use with caution and monitoring.
Breastfeeding: Use caution; monitor infant for effects.
Elderly: Higher risk of hypotension; start low and titrate slowly.
Children: Not recommended due to lack of safety data.
Renal/Hepatic Impairment: Adjust or avoid in severe cases.
Additional Precautions
- Inform your doctor about liver disease, heart conditions, or grapefruit juice consumption before starting this medication.
- Avoid alcohol to reduce vasodilation and dizziness risk.
- Use with caution in patients with a history of heart block.
Overdose and Management of Felodipine
Overdose Symptoms
- Dizziness, flushing, or headache.
- Severe cases: Profound hypotension, bradycardia, or cardiac arrest.
- Nausea, lethargy, or syncope as early signs.
- Coma or shock with extremely high doses.
Immediate Actions
Contact the Medical Team: Seek immediate medical help.
Supportive Care: Monitor vital signs, administer IV fluids, and use vasopressors (e.g., norepinephrine) if needed.
Specific Treatment: No specific antidote; use calcium gluconate to reverse calcium channel blockade under specialist guidance.
Monitor: Check ECG, blood pressure, and renal function for 24–48 hours.
Additional Notes
- Overdose risk is linked to accidental overdose or drug interactions; store securely.
- Report persistent symptoms (e.g., severe dizziness, chest pain) promptly.
Side Effects of Felodipine
Common Side Effects
- Peripheral Edema (10–20%, managed with leg elevation)
- Headache (5–15%, relieved with rest)
- Dizziness (5–10%, decreases with time)
- Flushing (3–8%, reduced with hydration)
- Fatigue (2–6%, managed with rest)
These effects may subside with adaptation.
Serious Side Effects
Seek immediate medical attention for:
- Cardiovascular: Severe hypotension, angina, or myocardial infarction.
- Neurological: Syncope or confusion.
- Hepatic: Jaundice or liver failure (rare).
- Allergic: Rash, angioedema, or anaphylaxis.
- Gingival: Significant gum overgrowth.
Additional Notes
Regular monitoring with blood pressure checks and liver function tests every 1–2 months is advised.
Patients with a history of heart failure should report worsening symptoms (e.g., shortness of breath).
Report any unusual symptoms (e.g., irregular heartbeat, severe swelling) immediately to a healthcare provider.
Drug Interactions with Felodipine
This active ingredient may interact with:
- CYP3A4 Inhibitors: Increases levels (e.g., ketoconazole, grapefruit juice); avoid or monitor.
- Beta-Blockers: Enhances hypotension risk; titrate carefully.
- Cimetidine: Raises levels; use cautiously.
- Diuretics: Potentiates hypotension; monitor electrolytes.
- Digoxin: Increases digoxin levels; check concentrations.
Action: Provide your healthcare provider with a complete list of medications.
Patient Education or Lifestyle
Medication Adherence: Take this calcium channel blocker as prescribed for hypertension or angina, following the daily schedule.
Monitoring: Report dizziness, swelling, or signs of hypotension immediately.
Lifestyle: Limit alcohol; engage in moderate exercise to support cardiovascular health.
Diet: Avoid grapefruit juice; maintain a low-sodium diet.
Emergency Awareness: Know signs of overdose or heart issues; seek care if present.
Follow-Up: Schedule regular check-ups every 1–3 months to monitor blood pressure and liver function.
Pharmacokinetics of Felodipine
Absorption: Oral, peak at 2.5–5 hours; bioavailability ~15% due to first-pass metabolism.
Distribution: Volume of distribution ~10 L/kg; 99% protein-bound.
Metabolism: Hepatic via CYP3A4 to inactive metabolites.
Excretion: Primarily biliary (70% as metabolites); renal (10%); half-life 11–16 hours.
Half-Life: 11–16 hours, prolonged in hepatic impairment.
Pharmacodynamics of Felodipine
This drug exerts its effects by:
Blocking L-type calcium channels in vascular smooth muscle, causing vasodilation.
Reducing peripheral resistance and blood pressure in hypertension.
Improving myocardial oxygen supply in angina via coronary dilation.
Exhibiting dose-dependent risks of hypotension and edema.
Storage of Felodipine
- Temperature: Store at 20–25°C (68–77°F); protect from moisture and light.
- Protection: Keep in original container, away from heat and humidity.
- Safety: Store in a secure location out of reach of children and pets due to cardiovascular risk.
- Disposal: Dispose of unused tablets per local regulations or consult a pharmacist.
Frequently Asked Questions (FAQs)
Q: What does Felodipine treat?
A: This medication treats high blood pressure and angina.
Q: Can this active ingredient cause swelling?
A: Yes, swelling is common; elevate legs if needed.
Q: Is Felodipine safe for the elderly?
A: Yes, with cautious dosing and monitoring.
Q: How is this drug taken?
A: Orally as extended-release tablets, once daily.
Q: How long is Felodipine treatment?
A: Often long-term, adjusted as needed.
Q: Can I use Felodipine if pregnant?
A: Yes, with caution; consult a doctor.
Regulatory Information
This medication is approved by:
U.S. Food and Drug Administration (FDA): Approved in 1991 (Plendil) for hypertension and angina.
European Medicines Agency (EMA): Approved for hypertension and stable angina.
Other Agencies: Approved globally for cardiovascular therapy; consult local guidelines.
References
- U.S. Food and Drug Administration (FDA). (2023). Plendil (Felodipine) Prescribing Information.
- Official FDA documentation detailing the drug’s approved uses, dosage, and safety.
- European Medicines Agency (EMA). (2023). Felodipine Summary of Product Characteristics.
- EMA’s comprehensive information on the medication’s indications and precautions in Europe.
- National Institutes of Health (NIH). (2023). Felodipine: MedlinePlus Drug Information.
- NIH resource providing detailed information on the drug’s uses, side effects, and precautions.
- World Health Organization (WHO). (2023). WHO Model List of Essential Medicines: Felodipine.
- WHO’s consideration of Felodipine for hypertension.
- Journal of the American College of Cardiology. (2022). Felodipine in Hypertension.
- Peer-reviewed article on Felodipine efficacy (note: access may require a subscription).
