Generic Name

Norvasc

Brand Names

for amlodipine) is a selective dihydropyridine calcium channel blocker that inhibits L‑type Ca²⁺ channels in vascular smooth muscle.

Mechanism

Norvasc (brand name for amlodipine) is a selective dihydropyridine calcium channel blocker that inhibits L‑type Ca²⁺ channels in vascular smooth muscle.
• Vasodilation → ↓ systemic vascular resistance and afterload.
• Minimal effect on cardiac conduction, reducing the risk of bradycardia.
• Clinically useful for lowering blood pressure and reducing myocardial oxygen demand, thereby improving angina control.

Pharmacokinetics

Norvasc:
• Absorption: Rapid, oral bioavailability ~90 %; peak 30‑60 min.
• Distribution: 95 % plasma protein bound; extensive hepatic distribution.
• Metabolism: Extensively first‑pass hepatic; CYP3A4 → inactive metabolites.
• Elimination: Biliary excretion; 7 % renal clearance.
• Half‑life: 30‑50 h (steady‑state ~35 h) → once‑daily dosing.
• Food effect: No clinically relevant interaction.

Indications

Norvasc is indicated for:
• Hypertension: as monotherapy or in combination therapy.
• Stable angina: diminishes frequency of angina attacks.
• Heart failure (add‑on therapy) to reduce afterload.
• Supine hypertension (rare) and off‑label use in post‑subarachnoid hemorrhage vasospasm.

Contraindications

• Contraindicated: Severe aortic stenosis; hypersensitivity to amlodipine or dihydropyridines.
• Warnings
• Hypotension in severe renal/hepatic impairment; use with caution.
• Hyperlipidemia: possible modest increase in LDL/total cholesterol.
• Drug interactions
• CYP3A4 inhibitors (ketoconazole, clarithromycin, HIV protease inhibitors) ↑ levels.
• CYP3A4 inducers (rifampin) ↓ efficacy.
• Cardiac risk: Rare onset of heart failure (≥5 % oral formulation).

Dosing

• Titration: +2.5 mg weekly; max 10 mg/day.
• Renal/hepatic disease: Start 2.5 mg, titrate slowly.
• Missed dose: Skip if >8 h elapsed; otherwise proceed with next dose.
• Switching: Maintain once therapeutic BP achieved; discontinue other agents gradually.

Adverse Effects

• Common (≥10 %)
• Peripheral edema (≈25 %)
• Headache (15‑20 %)
• Flushing, drows, palpitations.
• Serious (rare, <1 %)
• Severe hypotension, cardiogenic shock.
• Pulmonary edema/heart failure exacerbation.
• Stevens‑Johnson syndrome in susceptible patients.

Monitoring

• BP: baseline, weekly during titration, then monthly.
• Heart rate & ECG: baseline, during titration, and if symptomatic.
• Serum electrolytes: baseline, quarterly.
• Renal/hepatic panel: baseline, annually.
• Urinalysis: if edema or heart failure suspected.
• Lipid profile: annually for patients with dyslipidemia.

Clinical Pearls

• “Twin‑the‑Dish” principle: Amlodipine’s long half‑life allows dosing adjustments without abrupt withdrawal; sudden stop may trigger rebound hypertension.
• Flash‑dosing strategy: For resistant hypertension, start 10 mg/day then reduce to 5 mg after 2‑3 weeks to cut costs while preserving efficacy.
• Co‑administration with diuretics: Synergistic BP reduction; monitor electrolytes.
• Edema management: Reduce salt intake and consider adding a negative inotropic agent (beta‑blocker or nitrate) to counteract peripheral edema.
• Pregnancy: Category C; limited data, generally avoided unless benefits outweigh risks.
• Diabetes interaction: Severe hypotension can provoke hypoglycemia; educate diabetic patients and watch for symptoms.

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