Irbesartan Hydrochlorothiazide Zentiva (Hydrochlorothiazide, Irbesartan)

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

• Essential hypertension: lowers systolic and diastolic blood pressure and reduces cardiovascular risk.
• Hypertension requiring combination therapy: provides additive blood‑pressure reduction when monotherapy is insufficient.
• Salt‑sensitive hypertension: improves control by combining an ARB with a thiazide diuretic.

• Irbesartan selectively blocks AT1 angiotensin II receptors, preventing vasoconstriction and aldosterone‑mediated sodium retention. Hydrochlorothiazide inhibits Na⁺/Cl⁻ reabsorption in the distal convoluted tubule, promoting diuresis and reducing plasma volume. The combined actions decrease peripheral resistance and cardiac preload, resulting in lowered blood pressure.

Common Side Effects

• Dizziness: feeling light‑headed, especially after standing.
• Headache: mild to moderate intensity.
• Fatigue: general tiredness or lack of energy.
• Increased urination: due to the diuretic component.
• Electrolyte imbalance: mild changes in potassium or sodium levels.
• Mild gastrointestinal upset: nausea or abdominal discomfort.

Serious or Rare Side Effects

• Severe dehydration: marked fluid loss requiring medical attention.
• Significant electrolyte disturbances: severe hypo‑ or hyper‑kalemia.
• Acute renal impairment: sudden decline in kidney function.
• Angioedema: swelling of face, lips, tongue, or throat.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Blood dyscrasias: rare cases of agranulocytosis or pancytopenia.

Before initiating therapy, consider the following precautions:

• Blood pressure monitoring: ensure target levels are achieved without excessive drop.
• Renal function assessment: evaluate serum creatinine and eGFR, especially in patients with existing kidney disease.
• Electrolyte surveillance: check potassium and sodium levels regularly.
• Hepatic impairment: use with caution in severe liver disease.
• Elderly patients: start at lower doses and monitor for orthostatic hypotension.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Irbesartan/Hydrochlorothiazide may interact with several medicines.

Major Interactions (Avoid)

• Aliskiren: combined use can increase risk of renal dysfunction and hyperkalemia.
• Potassium‑sparing diuretics or supplements: may cause dangerous hyperkalemia.
• Lithium: concurrent use can raise lithium levels, leading to toxicity.

Moderate Interactions (Monitor Closely)

• NSAIDs: may blunt antihypertensive effect and affect renal function.
• ACE inhibitors: combined therapy can increase risk of hypotension and renal impairment.
• CYP2C9 inhibitors (e.g., fluconazole): may raise irbesartan plasma concentrations.