Irbesartan / Hydrochlorothiazide

What it is and how it works

Mechanism of Action Irbesartan Angiotensin II is a potent vasoconstrictor formed from angiotensin I in a reaction catalyzed by angiotensin-converting enzyme (ACE, kininase II). Angiotensin II is the principal pressor agent of the RAS and also stimulates aldosterone synthesis and secretion by adrenal cortex, cardiac contraction, renal resorption of sodium, activity of the sympathetic nervous system, and smooth muscle cell growth. Irbesartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively binding to the AT 1 angiotensin II receptor. There is also an AT 2 receptor in many tissues, but it is not involved in cardiovascular homeostasis.

Mechanism class: Angiotensin 2 Receptor Antagonists

Indications

® (irbesartan and hydrochlorothiazide) tablets are indicated for the treatment of hypertension. AVALIDE may be used in patients whose blood pressure is not adequately controlled on monotherapy. AVALIDE may also be used as initial therapy in patients who are likely to need multiple drugs to achieve their blood pressure goals. The choice of AVALIDE as initial therapy for hypertension should be based on an assessment of potential benefits and risks. Patients with stage 2 (moderate or severe) hypertension are at relatively high risk for cardiovascular events (such as strokes, heart attacks, and heart failure), kidney failure, and vision problems, so prompt treatment is clinically relevant. The decision to use a combination as initial therapy should be individualized and may be shaped by considerations such as the baseline blood pressure, the target goal, and the incremental likelihood of achieving goal with a combination compared with monotherapy.

Dosage and administration (summary)

General Considerations Maximum effects within 2 to 4 weeks after dose change. Renal impairment: Not recommended for patients with severe renal impairment (creatinine clearance <30 mL/min). ( 2.1 , 5.8 ) Hypertension Initiate with 150/12.5 mg. Titrate to 300/12.5 mg then 300/25 mg if needed. Replacement therapy: May be substituted for titrated components. General Considerations The side effects of irbesartan are generally rare and apparently independent of dose; those of hydrochlorothiazide are a mixture of dose-dependent (primarily hypokalemia) and dose-independent phenomena (e.g., pancreatitis), the former much more common than the latter.

Contraindications

is contraindicated in patients who are hypersensitive to any component of this product. Because of the hydrochlorothiazide component, this product is contraindicated in patients with anuria or hypersensitivity to other sulfonamide-derived drugs. Do not coadminister aliskiren with AVALIDE in patients with diabetes . Hypersensitivity to any component of this product. Anuria. Hypersensitivity to sulfonamide-derived drugs. Do not coadminister aliskiren with AVALIDE in patients with diabetes.

Warnings and precautions

Hypotension: Correct volume depletion prior to administration. Impaired renal function. Thiazide diuretics may cause an exacerbation or activation of systemic lupus erythematosus. Acute angle-closure glaucoma, acute myopia, and choroidal effusion. Fetal Toxicity AVALIDE can cause fetal harm when administered to a pregnant woman. Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death.

Pregnancy

Pregnancy Risk Summary AVALIDE can cause fetal harm when administered to a pregnant woman. Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death .

Storage and supply

Storage Store at 25°C (77°F); excursions permitted to 15°C–30°C (59°F–86°F) .

Source: Irbesartan And Hydrochlorothiazide (Avalide) — US FDA prescribing information, 2025-10-07, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.