Felodipine (Dihydropyridine)
Related Subjects:
|Calcium Channel Blockers
|Amlodipine
|Nifedipine
|Essential Hypertension
💊 Felodipine is a dihydropyridine calcium channel blocker given as a once-daily modified-release tablet for hypertension and angina. It is similar to amlodipine but is metabolised by CYP3A4 and is very sensitive to grapefruit juice.
📖 About
- Highly vascular-selective, with little direct effect on the heart.
- Always check the BNF for up-to-date prescribing advice.
⚙️ Mode of Action
- Blocks L-type calcium channels in arteriolar smooth muscle → vasodilation → ↓ systemic vascular resistance and BP.
- Reflex sympathetic activation can cause tachycardia and flushing.
🎯 Indications
- Hypertension.
- Angina prophylaxis.
💊 Dose (modified-release, swallow whole)
| Indication | Dose |
|---|
| Hypertension | Initially 5 mg once daily (2.5 mg in older people); usual 5–10 mg; max 20 mg daily |
| Angina | Initially 5 mg once daily, increased if necessary to max 10 mg daily |
| Hepatic impairment | Consider 2.5 mg starting dose |
🔄 Interactions
- Grapefruit juice: can raise felodipine levels several-fold - avoid.
- CYP3A4 inhibitors (clarithromycin, erythromycin, itraconazole, ritonavir): ↑ levels → hypotension, oedema.
- CYP3A4 inducers (rifampicin, carbamazepine, phenytoin, St John's wort): ↓ effect.
- Tacrolimus: felodipine may raise tacrolimus levels.
- Additive hypotension with other antihypertensives.
⚠️ Cautions
- Hepatic impairment (reduced clearance).
- Elderly (start low).
- Pregnancy: avoid (animal toxicity); breastfeeding - avoid.
🚫 Contraindications
- Cardiogenic shock.
- Significant aortic stenosis and dynamic LV outflow obstruction.
- Unstable angina; within 1 month of MI.
- Uncontrolled heart failure.
💥 Side Effects
- Very common: peripheral oedema.
- Common: headache, flushing, dizziness, palpitations, tachycardia.
- Uncommon/rare: gingival hyperplasia, rash, fatigue, nausea, hypotension, impotence.
☠️ Overdose
- Severe hypotension, bradycardia or tachycardia, metabolic acidosis, hyperglycaemia (CCBs block insulin release); coma in severe cases.
- Follow TOXBASE: IV calcium, vasopressors, high-dose insulin euglycaemia therapy.
📚 References
