Generic Name

Felodipine

Mechanism

Felodipine is a long‑acting dihydropyridine calcium‑channel blocker (CCB).
• Inhibits L‑type voltage‑gated Ca²⁺ channels in vascular smooth muscle.
• Causes predominant arterial vasodilation, reducing systemic vascular resistance.
• Minimal effects on myocardial contractility or conduction, making it suitable for isolated hypertension and some forms of angina.

Pharmacokinetics

• Absorption: Oral bioavailability ≈ 30–50 %; absorption is delayed by food (↑ plasma levels).
• Distribution: Highly protein‑bound (≈ 95 %).
• Metabolism: Extensive first‑pass hepatic metabolism via CYP3A4; metabolites are inactive.
• Elimination: ~80 % excreted fecally (biliary), 20 % renally.
• Half‑life: 24–36 h, supporting once‑daily dosing.
• Drug‑Drug Interactions:
• Strong CYP3A4 inhibitors (ketoconazole, itraconazole) ↑ felodipine levels → ↑ hypotension.
• CYP3A4 inducers (rifampin, carbamazepine) ↓ exposure → ↓ efficacy.

Indications

• Primary hypertension (most common).
• Stable angina pectoris (when tolerated and no contraindications).
• Off‑label: adjunct therapy in vasospastic disorders, certain vasodilatory disorders.

Contraindications

• Severe hepatic impairment – reduced metabolism & increased toxicity.
• Hypotension – especially severe or symptomatic post‑ural/orthostatic.
• Pregnancy – Category C; avoid in the third trimester.
• Concurrent use with non‑selective beta‑blockers (e.g., propranolol) in patients with coronary disease can mask bradycardia/hypotension.
• Be cautious in patients with heart failure or left ventricular hypertrophy; monitor cardiac function.

Dosing

• Adult Induction: 2.5 mg orally once daily (preferably at night).
• Maintenance: Titrate by 2.5 mg increments every 2–3 weeks to 5 mg daily.
• Maximum: 10 mg daily (5 mg bid is acceptable if needed).
• Special Populations:
• Elderly: start at lower dose, titrate cautiously.

‑ Hepatic impairment: dose adjustment recommended; follow pharmacokinetic guidance.
• Administration Tips: Take with a full meal to optimize absorption; avoid alcohol which may potentiate hypotensive effect.

Adverse Effects

• Common:
• Peripheral edema (especially ankle/foot).
• Flushing, headache, nasal congestion.
• Dry mouth, GI upset.
• Serious (rare):
• Severe hypotension (symptomatic).
• Supine hypertension (if used with nitrates).
• Allergic reactions (rash, angioedema).
• Monitoring for cardiovascular symptoms—regular BP checks and assessment of edema.

Monitoring

• Blood Pressure: Clinic or home BP before each dose adjustment.
• Serum Sodium & Potassium: Check if edema pronounced.
• Renal & Hepatic Function: Baseline, then at 3–6 month intervals for patients ≥65 y or with comorbidities.
• Electrocardiogram: Baseline and if symptomatic (to assess for conduction changes).

Clinical Pearls

• Long‑acting formulation: Gives steadier BP control vs short‑acting felodipine; avoid twice‑daily regimens unless absolutely required.
• Food–Drug Interaction: A high‑fat meal can increase bioavailability by ~50 %; counsel patients to maintain consistent meal timing relative to dose.
• Avoid abrupt discontinuation—may precipitate rebound hypertension.
• Use with caution in coronary artery disease—while vasodilatory, it can mask ischemic angina; monitor for chest discomfort.
• Beware of “contradictory” nitrate therapy—combination can produce dangerous hypotension; consider timing or alternative agents.
• Pregnancy & Breastfeeding: Limited data; if essential, use lowest effective dose and consider off‑label alternatives.
• Transdermal nicotine users? Not a major interaction, but note potential additive antihypertensive effects.
• CYP3A4 modulators: Dose adjustment is critical; a 7‑day course of ketoconazole may necessitate a temporary dose halving.

These high‑yield points help clinicians manage Felodipine effectively while minimizing complications and optimizing therapeutic outcomes.