Felodipine

1. Introduction

Felodipine is a dihydropyridine calcium channel blocker (CCB) used primarily to manage hypertension and angina pectoris. It works by relaxing vascular smooth muscle, leading to vasodilation and reduced blood pressure. Unlike some other calcium channel blockers, felodipine has minimal effects on cardiac conduction and contractility, making it a safer option for patients with heart failure or conduction abnormalities.

2. Indications

  • Approved Indications:
    • Hypertension (alone or in combination with other antihypertensive agents).
    • Stable angina pectoris.
  • Off-Label Uses:
    • Raynaud’s phenomenon.

3. Dosage

  • Adults:
    • Hypertension: 5 mg once daily. Adjust based on response, with a usual maintenance dose of 5–10 mg once daily. Maximum: 20 mg/day.
    • Stable Angina: 5–10 mg once daily.
  • Elderly:
    • Start with 2.5 mg once daily, as they may be more sensitive to hypotensive effects.
  • Children:
    • Safety and efficacy in children have not been established.

4. Administration

  • Take orally, once daily, preferably in the morning.
  • Swallow tablets whole with water; do not crush or chew.
  • Avoid taking with grapefruit juice, as it can increase felodipine levels in the blood.

5. Forms Available

  • Extended-release tablets: 2.5 mg, 5 mg, 10 mg.

6. Side Effects

6.1. Common Side Effects

  • Headache.
  • Dizziness.
  • Flushing.
  • Ankle swelling (peripheral oedema).

6.2. Less Common Side Effects

  • Fatigue.
  • Palpitations.
  • Nausea.

6.3. Rare but Serious Side Effects

  • Gingival hyperplasia.
  • Severe hypotension.
  • Allergic reactions (e.g., rash, itching, swelling).

7. Warnings

  • Hypotension: Risk of significant blood pressure reduction, particularly in patients with severe aortic stenosis or volume depletion.
  • Heart Failure: Use cautiously in patients with severe heart failure, as calcium channel blockers may exacerbate symptoms.
  • Peripheral Oedema: Common, dose-dependent side effect; not responsive to diuretics.

8. Precautions

  • Avoid abrupt discontinuation, as it may lead to rebound hypertension.
  • Use cautiously in patients with impaired liver function, as felodipine is extensively metabolised by the liver.
  • Grapefruit juice significantly increases felodipine plasma levels and should be avoided.

9. Interactions

  • Drug-Drug Interactions:
    • CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): Increase felodipine levels and risk of side effects.
    • CYP3A4 inducers (e.g., rifampin, phenytoin): Reduce felodipine efficacy.
    • Beta-blockers: Additive antihypertensive effect but increased risk of bradycardia.
    • NSAIDs: May reduce antihypertensive efficacy.
  • Drug-Food Interactions:
    • Grapefruit juice increases plasma concentration, leading to an enhanced risk of side effects.

10. Monitoring Parameters

  • Blood pressure response (effectiveness in reducing hypertension).
  • Signs of peripheral oedema or other side effects.
  • Heart rate in patients receiving combination therapy with beta-blockers.

11. Use in Children

  • Not approved for use in paediatric populations.

12. Use in Pregnancy

  • Category C: Use only if the potential benefits outweigh risks. Animal studies have shown adverse effects on foetal development.

13. Use in Elderly

  • Elderly patients are more prone to hypotension and associated symptoms (e.g., dizziness). Start at the lowest dose (2.5 mg/day) and monitor closely.

14. Use in Kidney Disease

  • No dose adjustment is required, as felodipine is primarily metabolised in the liver.

15. Use in Liver Disease

  • Use with caution in patients with hepatic impairment, as felodipine metabolism may be reduced, leading to increased plasma levels. Consider starting with a lower dose.

16. Patient Counselling Points

  • Take felodipine exactly as prescribed, at the same time each day.
  • Avoid grapefruit juice while taking this medication.
  • Inform your doctor if you experience swelling in the ankles, severe dizziness, or irregular heartbeat.
  • Do not stop taking felodipine abruptly without consulting your doctor.
  • Maintain a healthy diet and lifestyle to optimise blood pressure control.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
PlendilAstraZeneca$40–80 (30 tablets, 5 mg)
FelodilCipla$20–40 (30 tablets, 5 mg)
Generic FelodipineVarious$10–25 (30 tablets, 5 mg)

18. FAQs (15 Questions)

  1. What is felodipine used for?
    Felodipine is used to treat high blood pressure (hypertension) and stable angina.
  2. How does felodipine work?
    It relaxes blood vessels, reducing vascular resistance and lowering blood pressure.
  3. Can felodipine cause swelling?
    Yes, peripheral oedema (swelling, especially in the ankles) is a common side effect.
  4. How long does it take for felodipine to work?
    Blood pressure reduction is usually noticeable within 2–4 hours, with full effects in a few weeks.
  5. What should I avoid while taking felodipine?
    Avoid grapefruit juice, as it can increase the risk of side effects.
  6. Can felodipine be taken during pregnancy?
    It should only be used if the potential benefits outweigh the risks. Consult your doctor before use.
  7. Does felodipine interact with other medications?
    Yes, it interacts with CYP3A4 inhibitors, inducers, and beta-blockers.
  8. What should I do if I miss a dose?
    Take it as soon as you remember, but skip it if it’s close to the next dose. Do not double up.
  9. Can felodipine cause headaches?
    Yes, headaches are a common side effect, especially during the initial weeks of treatment.
  10. Is felodipine safe for elderly patients?
    Yes, but they may require lower starting doses due to increased sensitivity to side effects.
  11. Can felodipine cause dizziness?
    Yes, dizziness may occur, particularly with the first dose or during dose adjustments.
  12. How should felodipine be stored?
    Store at room temperature, away from light and moisture.
  13. Does felodipine affect kidney function?
    No, felodipine does not adversely affect kidney function and does not require dose adjustments for kidney disease.
  14. Can I stop taking felodipine suddenly?
    No, abrupt discontinuation may cause rebound hypertension. Consult your doctor before stopping.
  15. Can felodipine be used with beta-blockers?
    Yes, but monitor for additive blood pressure-lowering effects and bradycardia.