Irbesartán/Hidroclorotiazida Sandoz (Hydrochlorothiazide, Irbesartan)

Irbesartan/Hydrochlorothiazide is employed to manage hypertension, a chronic condition characterized by elevated arterial pressure.

• Essential hypertension: reduces systolic and diastolic blood pressure, improving cardiovascular risk profile.
• Hypertension with fluid retention: provides combined antihypertensive and diuretic effect to lower volume overload.
• Hypertension requiring an angiotensin II receptor blocker and thiazide diuretic: simplifies therapy by delivering both agents in one tablet.
• Resistant hypertension: offers additional blood pressure reduction when monotherapy is insufficient.
• Hypertension with concomitant edema: the diuretic component helps reduce fluid overload.

• Irbesartan selectively antagonizes the angiotensin II type 1 (AT1) receptor, preventing vasoconstriction, aldosterone secretion and sodium reabsorption. Hydrochlorothiazide acts on the distal convoluted tubule, inhibiting the Na⁺‑Cl⁻ symporter, which promotes natriuresis and diuresis, decreasing plasma volume. These effects are additive, allowing a single tablet to achieve greater antihypertensive efficacy than either component alone.

Irbesartan/Hydrochlorothiazide may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Dizziness or light‑headedness, especially after the first dose.
• Headache, often mild and transient.
• Increased urination due to the diuretic effect.
• Electrolyte disturbances such as low potassium or sodium levels.
• Fatigue or general weakness.
• Nausea or mild gastrointestinal discomfort.

Serious or Rare Side Effects

• Severe hypotension leading to fainting or shock.
• Angioedema or swelling of the face, lips, tongue or throat.
• Acute kidney injury or a rapid rise in serum creatinine.
• Hyperkalemia or dangerously high potassium levels.
• Blood dyscrasias such as agranulocytosis or thrombocytopenia.

When prescribing Irbesartan/Hydrochlorothiazide, clinicians should observe several precautionary measures to ensure safe use.

• Monitor blood pressure: check regularly to avoid excessive hypotension.
• Assess renal function: evaluate serum creatinine and eGFR before and during therapy.
• Check electrolytes: especially potassium and sodium levels due to diuretic effect.
• Use caution in patients with hepatic impairment: dose adjustment may be required.
• Avoid in severe hyperkalemia or anuria: contraindicated in these conditions.
• Store at ambient temperature: keep in original packaging, protect from moisture.

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

Major Interactions (Avoid)

• Aliskiren: combined use may increase risk of renal impairment and hyperkalemia.
• Potassium‑sparing diuretics or supplements: can cause dangerous hyperkalemia.
• ACE inhibitors or other ARBs: additive effects on potassium and renal function.
• Lithium: increased lithium levels and toxicity risk.
• NSAIDs (high dose): may reduce antihypertensive effect and impair renal function.

Moderate Interactions (Monitor Closely)

• Antidiabetic agents: diuretic may affect glucose control, requiring dose adjustment.
• CYP2C9 inhibitors (e.g., fluconazole): may increase hydrochlorothiazide plasma levels.
• Other antihypertensives: additive blood pressure lowering, monitor for hypotension.