Drug Guide
Candesartan Cilexetil; Hydrochlorothiazide
Classification
Therapeutic: Antihypertensive, Diuretic
Pharmacological: Angiotensin II receptor blocker (ARB), Thiazide diuretic
FDA Approved Indications
- Hypertension
- Heart failure (used in combination with other agents)
Mechanism of Action
Candesartan blocks angiotensin II receptors, leading to vasodilation and reduced blood pressure. Hydrochlorothiazide inhibits sodium reabsorption in the distal tubules of the nephron, increasing sodium, chloride, and water excretion, which lowers blood pressure.
Dosage and Administration
Adult: Typically, 1 tablet once daily, dose may be adjusted based on clinical response.
Pediatric: Not approved for pediatric use.
Geriatric: Start at lower doses due to increased sensitivity and risk of hypotension.
Renal Impairment: Use caution; dosage adjustment may be necessary based on renal function.
Hepatic Impairment: Use with caution; no specific dose adjustment recommended.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Candesartan approximately 99% protein-bound; hydrochlorothiazide excreted unchanged.
Metabolism: Candesartan undergoes minimal metabolism; hydrochlorothiazide is not extensively metabolized.
Excretion: Primarily via urine; hydrochlorothiazide is excreted unchanged.
Half Life: Candesartan ~9 hours; hydrochlorothiazide ~6-15 hours.
Contraindications
- Hypersensitivity to candesartan or hydrochlorothiazide
- Pregnancy (especially second and third trimesters)
Precautions
- History of angioedema with previous ACE inhibitor or ARB use
- Severe hepatic impairment
- Electrolyte imbalance (hyperkalemia, hyponatremia)
- Volume depletion or hypotension
Adverse Reactions - Common
- Dizziness (Common)
- Hypotension (Common)
- Dizziness upon standing (Common)
Adverse Reactions - Serious
- Angioedema (Rare)
- Serum hyperkalemia (Less common)
- Electrolyte disturbances (hypokalemia, hyponatremia) (Less common)
Drug-Drug Interactions
- Potassium-sparing diuretics, Potassium supplements, NSAIDs, Lithium
Drug-Food Interactions
- Avoid excessive salt substitutes containing potassium
Drug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure, serum electrolytes, renal function, and for signs of angioedema.
Diagnoses:
- Risk for electrolyte imbalance
- Risk for hypotension
Implementation: Administer medication consistently at same time each day; monitor vital signs and laboratory values.
Evaluation: Assess blood pressure to ensure therapeutic effect; monitor for adverse reactions.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report any symptoms of angioedema, severe dizziness, or hyperkalemia.
- Avoid potassium supplements or salt substitutes containing potassium unless directed.
- Stand up slowly to reduce dizziness.
Special Considerations
Black Box Warnings:
- Pregnancy risk; can cause fetal injury or death if used during pregnancy.
Genetic Factors: Genetic factors affecting pharmacokinetics are not well established.
Lab Test Interference: May increase serum potassium and serum creatinine; monitor accordingly.
Overdose Management
Signs/Symptoms: Severe hypotension, dizziness, electrolyte disturbances.
Treatment: Discontinue medication, provide supportive care, monitor vital signs and electrolytes, administer fluids or vasopressors as needed.
Storage and Handling
Storage: Store at room temperature, away from light and moisture.
Stability: Stable under typical conditions, consult package insert for expiration date.