Irbesartan/Hydrochloorthiazide Viatris (Hydrochlorothiazide, Irbesartan)

Irbesartan/Hydrochlorothiazide acts on the renin‑angiotensin‑aldosterone system and renal sodium handling to control elevated blood pressure.

• Essential hypertension: lowers systolic and diastolic pressure in patients with primary hypertension.
• Secondary hypertension: assists in blood‑pressure control when hypertension is caused by another condition.
• Hypertension with fluid retention: combines vasodilation and diuresis to reduce volume overload and improve pressure control.

• Irbesartan selectively blocks the AT1 receptor, preventing angiotensin II‑mediated vasoconstriction and aldosterone release. Hydrochlorothiazide inhibits sodium‑chloride reabsorption in the distal convoluted tubule, increasing urinary excretion of water and electrolytes, which together reduce peripheral resistance and plasma volume, leading to lower arterial pressure.

Adverse reactions may vary in frequency and severity.

Common Side Effects

• Dizziness: feeling light‑headed, especially after standing.
• Headache: mild to moderate pain in the head region.
• Fatigue: unusual tiredness or lack of energy.
• Increased urination: more frequent need to void.
• Electrolyte imbalance: low potassium or sodium levels.

Serious or Rare Side Effects

• Severe dehydration: marked fluid loss requiring medical attention.
• Acute kidney injury: sudden decline in renal function.
• Allergic reaction: rash, itching, swelling, or difficulty breathing.
• Blood cell abnormalities: low white blood cells or platelets.
• Significant hypotension: dangerously low blood pressure.

Before initiating therapy, clinicians should evaluate patient‑specific factors and monitor for potential risks.

• Blood pressure monitoring: check regularly to ensure therapeutic targets are met.
• Renal function assessment: evaluate serum creatinine and eGFR before and during treatment.
• Electrolyte surveillance: monitor potassium and sodium levels, especially in patients on other diuretics.
• Caution in elderly: start at lower doses and watch for orthostatic symptoms.
• Avoid in severe hepatic impairment: limited data suggest increased exposure.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Irbesartan/Hydrochlorothiazide may alter the effect of several co‑administered medicines.

Major Interactions (Avoid)

• Aliskiren (in diabetes): combined use can increase risk of renal impairment and hyperkalemia.
• Potassium‑sparing diuretics: may cause dangerous elevations in serum potassium.
• ACE inhibitors: concurrent use raises the chance of hyperkalemia and renal dysfunction.
• Lithium: thiazide component can raise lithium concentrations, risking toxicity.

Moderate Interactions (Monitor Closely)

• NSAIDs: may blunt antihypertensive response and affect renal function.
• Other antihypertensives: additive blood‑pressure lowering may require dose adjustments.
• Loop diuretics: combined diuretic effect can lead to excessive volume depletion.