Nurses Compass
Drug Guide
Amlodipine Besylate
Classification
Therapeutic: Antihypertensive, Antianginal
Pharmacological: Calcium Channel Blocker (Dihydropyridine)
FDA Approved Indications
- Chronic stable angina pectoris
- Vasospastic angina (Prinzmetal's or variant angina)
- Hypertension
Mechanism of Action
Amlodipine inhibits the influx of calcium ions into vascular smooth muscle and cardiac muscle, resulting in relaxation of vascular smooth muscle and coronary vasodilation, decreasing blood pressure and myocardial oxygen demand.
Dosage and Administration
Adult: Starting dose typically 5 mg once daily; can be titrated to 10 mg based on response.
Pediatric: Not approved for use in children under 6 years of age; for children 6 years and older, dose as per physician discretion, generally starting with 2.5-5 mg once daily.
Geriatric: Start at lower dose (e.g., 2.5 mg) and titrate carefully.
Renal Impairment: No dose adjustment needed in mild to moderate impairment; use caution and monitor in severe impairment.
Hepatic Impairment: Use with caution; start at lower dose due to reduced clearance.
Pharmacokinetics
Absorption: Well absorbed with oral bioavailability of approximately 64-90%.
Distribution: Widely distributed; protein binding approximately 95%.
Metabolism: Extensively metabolized in the liver, primarily via CYP3A4 enzymes.
Excretion: Metabolites excreted mainly in urine; less than 10% is unchanged drug.
Half Life: Averages 30-50 hours, allowing for once-daily dosing.
Contraindications
- Hypersensitivity to amlodipine or dihydropyridines.
- Severe hypotension.
- Obstruction of the left ventricle.
Precautions
- Use cautiously in heart failure, hepatic impairment, or in combo with other antihypertensive agents; monitor blood pressure and edema.
Adverse Reactions - Common
- Swelling (edema) (Common)
- Dizziness (Common)
- Flushing (Common)
- Palpitations (Common)
Adverse Reactions - Serious
- Severe hypotension (Rare)
- Worsening angina or myocardial infarction (Rare)
- Allergic reactions, including angioedema (Rare)
Drug-Drug Interactions
- Simvastatin (risk of myopathy), CYP3A4 inhibitors (e.g., azole antifungals, macrolides)
Drug-Food Interactions
- Grapefruit juice (increases plasma levels)
Drug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure and heart rate regularly; assess for signs of edema, dizziness, or fluid overload.
Diagnoses:
- Risk for falls due to hypotension or dizziness.
- Ineffective tissue perfusion.
Implementation: Administer medication as prescribed; counsel patient on potential side effects and interactions; encourage compliance and regular monitoring.
Evaluation: Assess blood pressure response and symptom control; adjust dose as needed.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report swelling, dizziness, or chest pain.
- Avoid grapefruit juice and alcohol.
- Do not discontinue abruptly without physician advice.
Special Considerations
Black Box Warnings:
- None
Genetic Factors: CYP3A4 genetic variations may alter drug metabolism.
Lab Test Interference: None noted.
Overdose Management
Signs/Symptoms: Severe hypotension, tachycardia or bradycardia, dizziness, or loss of consciousness.
Treatment: Supportive care, vasopressors if needed, calcium gluconate IV may be used in calcium channel blocker overdose; gastric lavage or activated charcoal if ingestion is recent.
Storage and Handling
Storage: Store at room temperature, away from moisture and heat.
Stability: Stable until expiration date on packaging.