Irbesartan Viatris (Irbesartan)

• Irbesartan, an angiotensin II receptor blocker, acts on the renin‑angiotensin system to lower blood pressure and protect kidney function.
• Hypertension: reduces systemic vascular resistance, lowers systolic and diastolic blood pressure, and improves overall cardiovascular control in patients with essential hypertension.
• Diabetic nephropathy: slows the decline of renal function, reduces albuminuria, and helps preserve kidney health in patients with type 2 diabetes and established nephropathy.

• Irbesartan selectively blocks angiotensin II type 1 (AT1) receptors on vascular smooth‑muscle cells, adrenal glands and renal tubular cells. By preventing angiotensin II binding, it inhibits vasoconstriction, aldosterone secretion and sodium‑water retention, leading to vasodilation, reduced blood pressure and decreased intraglomerular pressure, which together protect cardiovascular and renal systems.

Irbesartan may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Dizziness: sensation of light‑headedness, especially after standing.
• Headache: mild to moderate intensity.
• Fatigue: feeling of tiredness or lack of energy.
• Nausea: upset stomach with possible vomiting.
• Back pain: musculoskeletal discomfort.
• Upper respiratory infection: symptoms such as cough or sore throat.

Serious or Rare Side Effects

• Angioedema: swelling of face, lips, tongue or airway requiring immediate medical attention.
• Renal failure: sudden decrease in kidney function, indicated by rising creatinine.
• Hepatic injury: signs of liver dysfunction such as jaundice or elevated enzymes.
• Severe hypotension: marked drop in blood pressure causing fainting.
• Neutropenia: dangerously low white‑blood‑cell count.
• Anaphylaxis: life‑threatening allergic reaction with rash, breathing difficulty.

When prescribing Irbesartan, clinicians should consider several safety measures to minimize risks.

• Monitor blood pressure: adjust dose to maintain target levels.
• Assess renal function: check serum creatinine and eGFR before and during therapy.
• Check serum potassium: avoid hyperkalemia, especially with potassium‑sparing agents.
• Use caution in hepatic impairment: dose may need adjustment in patients with liver disease.
• Avoid use in pregnancy: drug is contraindicated in the second and third trimesters (Category D).
• Store at room temperature: keep in the original packaging, protect from moisture and light.

Irbesartan can interact with other medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Aliskiren (in diabetic patients): combined use may increase risk of renal impairment, hyperkalemia and hypotension.
• Potassium‑sparing diuretics (e.g., spironolactone): may cause dangerous elevations in serum potassium.
• ACE inhibitors: concurrent use heightens the chance of hyperkalemia and renal dysfunction.
• Lithium: Irbesartan can raise lithium concentrations, risking toxicity.
• NSAIDs (high‑dose): may reduce antihypertensive effect and impair kidney function.

Moderate Interactions (Monitor Closely)

• Thiazide diuretics: may enhance antihypertensive effect, requiring dose adjustment.
• CYP2C9 inhibitors (e.g., fluconazole): can increase Irbesartan plasma levels modestly.
• Antacids (aluminum or magnesium): may affect absorption if taken simultaneously.
• Digoxin: monitor levels as renal changes can affect clearance.
• Warfarin: occasional reports of altered INR, necessitating closer monitoring.