Drug Guide
Amlodipine Besylate, Hydrochlorothiazide, Valsartan
Classification
Therapeutic: Antihypertensive
Pharmacological: Combination calcium channel blocker, thiazide diuretic, and angiotensin II receptor blocker
FDA Approved Indications
- Hypertension
Mechanism of Action
Amlodipine inhibits calcium ion influx into vascular smooth muscle and cardiac muscle, leading to vasodilation. Hydrochlorothiazide promotes diuresis by inhibiting sodium reabsorption in the distal tubules. Valsartan blocks angiotensin II receptors, resulting in vasodilation and decreased aldosterone secretion.
Dosage and Administration
Adult: Typically, one tablet once daily. Dose adjustments based on response.
Pediatric: Not generally recommended for pediatric use.
Geriatric: Start at lower doses due to increased sensitivity and risk of hypotension.
Renal Impairment: Adjust dose based on severity of impairment.
Hepatic Impairment: Use with caution; monitor closely; no specific dose adjustment available.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Widely distributed; protein binding varies among components.
Metabolism: Hydrochlorothiazide minimally metabolized; amlodipine undergoes partial hepatic metabolism; valsartan minimally metabolized.
Excretion: Renal excretion for hydrochlorothiazide and valsartan; amlodipine undergoes hepatic metabolism with some renal excretion.
Half Life: Amlodipine: ~30-50 hours; valsartan: ~6 hours; hydrochlorothiazide: ~6-15 hours.
Contraindications
- Hypersensitivity to any component.
- Pregnancy (especially second and third trimesters).
- Angioedema related to previous ACE inhibitor or ARB therapy.
Precautions
- Monitor renal function and electrolyte levels.
- Use with caution in heart failure, hepatic impairment, or volume-depleted patients.
- Pregnancy and lactation: contraindicated or use with caution.
Adverse Reactions - Common
- Swelling (edema) (Common)
- Dizziness (Common)
- Fatigue (Common)
- Increased urination (thiazide component) (Common)
Adverse Reactions - Serious
- Hypotension (Serious)
- Angioedema (Serious)
- Electrolyte imbalances (hypokalemia, hyponatremia) (Serious)
- Renal impairment (Serious)
Drug-Drug Interactions
- Other antihypertensives, potassium-sparing diuretics, lithium, NSAIDs, drugs affecting renal function.
Drug-Food Interactions
- Excess potassium intake, alcohol.
Drug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure, heart rate, renal function, serum electrolytes, especially potassium and sodium.
Diagnoses:
- Ineffective tissue perfusion related to decreased blood pressure.
- Risk of electrolyte imbalance.
Implementation: Administer as prescribed, monitor response and side effects, educate patient about signs of hypotension and electrolyte issues.
Evaluation: Assess blood pressure response, electrolyte levels, renal function periodically.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Do not skip doses.
- Rise slowly to prevent dizziness.
- Report swelling, difficulty breathing, or signs of electrolyte imbalance.
Special Considerations
Black Box Warnings:
- Fetal toxicity in pregnancy.
Genetic Factors: None specified.
Lab Test Interference: May affect serum electrolytes and kidney function tests.
Overdose Management
Signs/Symptoms: Severe hypotension, tachycardia or bradycardia, dizziness, electrolyte disturbances.
Treatment: Discontinue medication, provide supportive care, administer activated charcoal if ingestion was recent, and manage hypotension with IV fluids or vasopressors as appropriate.
Storage and Handling
Storage: Store at room temperature, protected from moisture and light.
Stability: Stable under normal conditions.