Nurses Compass
Drug Guide
Irbesartan
Classification
Therapeutic: Antihypertensive, Angiotensin II Receptor Blocker (ARB)
Pharmacological: Angiotensin II receptor antagonist
FDA Approved Indications
- Hypertension
- Diabetic nephropathy in patients with type 2 diabetes and hypertension
Mechanism of Action
Irbesartan blocks the angiotensin II receptors in vascular smooth muscle and the adrenal gland, leading to vasodilation and decreased aldosterone secretion, which reduces blood pressure.
Dosage and Administration
Adult: Typically 150 mg once daily, titrated up to 300 mg once daily as needed, depending on response.
Pediatric: Not recommended for children under 6 years old; for children aged 6 years and older, dosing should be individualized.
Geriatric: Monitor renal function and electrolytes; start at lower doses due to potential increased sensitivity.
Renal Impairment: Reduce dose in patients with creatinine clearance less than 60 mL/min; careful monitoring required.
Hepatic Impairment: Use with caution, starting with lower doses due to potential for increased exposure.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Extensive, approximately 95% protein-bound.
Metabolism: Partially metabolized in the liver; minor 6-hydroxymethyl and carboxylic acid metabolites.
Excretion: Excreted primarily in feces (about 70%) and urine (about 25%).
Half Life: Approximately 11-15 hours.
Contraindications
- History of hypersensitivity to irbesartan or other ARBs
- Pregnancy (especially at 2nd and 3rd trimesters)
Precautions
- Renal impairment, concomitant use with other agents affecting renal function, volume depletion, hyperkalemia, avoid during pregnancy and breastfeeding unless specifically advised.
Adverse Reactions - Common
- Hypotension (Uncommon)
- Dizziness (Common)
- Fatigue (Common)
- Elevated serum potassium (Uncommon)
Adverse Reactions - Serious
- Angioedema (Rare)
- Acute renal failure (Uncommon)
- Hyperkalemia (Uncommon)
Drug-Drug Interactions
- Enhances hypotensive effect when combined with other antihypertensives, potassium-sparing diuretics, or potassium supplements.
- NSAIDs may reduce the antihypertensive effect and increase risk of renal impairment.
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure, renal function, and serum electrolytes regularly.
Diagnoses:
- Ineffective tissue perfusion related to hypotension.
- Risk for electrolyte imbalance.
Implementation: Administer as prescribed, preferably at the same time each day. Monitor for signs of hypotension and hyperkalemia.
Evaluation: Assess blood pressure response and adverse effects.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report signs of dizziness, swelling, or difficulty breathing.
- Avoid potassium-rich foods and potassium supplements unless directed.
- Maintain hydration and follow dietary recommendations.
Special Considerations
Black Box Warnings:
- Pregnancy risk; discontinue as soon as pregnancy is detected.
- Fetal toxicity can result in fetal death or injury.
Genetic Factors: Not specifically related to genetic factors.
Lab Test Interference: May cause increases in serum potassium and serum creatinine.
Overdose Management
Signs/Symptoms: Severe hypotension, tachycardia or bradycardia, dizziness, hyperkalemia.
Treatment: Discontinue drug, initiate supportive care including IV fluids; consider vasopressors for persistent hypotension; monitor serum electrolytes and renal function.
Storage and Handling
Storage: Store at room temperature away from moisture, heat, and light.
Stability: Stable under recommended storage conditions.