Cavazide

• Essential (primary) hypertension — indicated for the treatment of high blood pressure in patients for whom combination therapy is appropriate.
• Patients not adequately controlled on monotherapy — used when blood pressure is insufficiently controlled with irbesartan or hydrochlorothiazide alone.
• Replacement therapy — for patients already stabilized on both irbesartan and hydrochlorothiazide at the same dose as separate tablets, to simplify treatment.
• Clinically accepted off-label use — may be considered in hypertensive patients requiring multiple antihypertensive mechanisms and with features such as left ventricular hypertrophy or proteinuria, provided combination therapy is appropriate.

Adults

• Usual starting dose: Irbesartan 150 mg + Hydrochlorothiazide 12.5 mg once daily.
• If additional blood pressure reduction is needed after 2–4 weeks, increase to Irbesartan 300 mg + Hydrochlorothiazide 12.5 mg once daily.
• Maximum recommended dose: Irbesartan 300 mg + Hydrochlorothiazide 25 mg once daily.

Elderly

• No initial dose adjustment solely for age, but start at the lower strength and titrate cautiously.

Renal impairment

• Mild-to-moderate impairment: no specific dose adjustment needed, but careful monitoring is required.
• Severe impairment (creatinine clearance <30 mL/min) or anuria: use not recommended due to the thiazide component.

Hepatic impairment

• Mild-to-moderate impairment: use with caution.
• Severe hepatic impairment: use not recommended.

Pediatrics

• Safety and efficacy not established; use not recommended.

Administration

• Oral, once daily, with or without food.
• Preferably taken at the same time each day.

This fixed-dose combination contains two antihypertensive agents:

• Irbesartan — a selective angiotensin II type-1 (AT₁) receptor blocker that inhibits the vasoconstrictive and aldosterone-secreting effects of angiotensin II. This leads to vasodilation, reduced peripheral resistance, and decreased sodium and water retention.
• Hydrochlorothiazide — a thiazide diuretic that acts in the distal convoluted tubules of the nephron to inhibit sodium-chloride symporters, increasing sodium and water excretion, reducing plasma volume, and lowering cardiac output.
  Together, these agents provide additive blood pressure–lowering effects through complementary mechanisms: irbesartan blocks neurohormonal vasoconstriction, while hydrochlorothiazide reduces fluid volume and vascular reactivity.

Irbesartan

• Absorption: Rapid, peak plasma levels in 1.5–2 hours, bioavailability ~60–80%.
• Distribution: Highly protein-bound (~90%).
• Metabolism: Minimal hepatic metabolism (mainly CYP2C9).
• Elimination: Half-life ~11–15 hours; ~20% in urine, ~80% in feces.

Hydrochlorothiazide

• Absorption: Rapid, peak plasma levels in 1–5 hours; bioavailability ~60–80%.
• Distribution: Crosses placenta but minimal entry into CNS; protein binding ~40–70%.
• Metabolism: Not significantly metabolized.
• Elimination: Half-life ~6–15 hours; excreted unchanged in urine.

• Pregnancy: Contraindicated, especially in the 2nd and 3rd trimesters, due to risks from irbesartan (fetal toxicity, renal damage, oligohydramnios, fetal death) and hydrochlorothiazide (possible fetal/neonatal jaundice, thrombocytopenia, electrolyte disturbances).
• Lactation: Both components may be excreted in breast milk. Hydrochlorothiazide in high doses may cause intense diuresis in the mother and potentially affect milk production. Use not recommended while breastfeeding.
• Note: Safer alternatives should be used during pregnancy and lactation.

• Primary class: Antihypertensive combination
• Subclasses:
• Angiotensin II receptor blocker (ARB) – Irbesartan
• Thiazide diuretic – Hydrochlorothiazide

• Hypersensitivity to irbesartan, hydrochlorothiazide, or any component of the formulation.
• Pregnancy (especially 2nd and 3rd trimesters).
• Severe renal impairment (CrCl <30 mL/min) or anuria.
• Severe hepatic impairment.
• Refractory hyponatremia or hypercalcemia.
• Concomitant use with aliskiren in diabetic patients.

• Fetal toxicity: discontinue immediately if pregnancy occurs.
• Renal function impairment: risk increased in patients with bilateral renal artery stenosis or severe heart failure.
• Electrolyte disturbances: thiazide diuretics can cause hypokalemia, hyponatremia, hypomagnesemia, and hypercalcemia; ARBs may cause hyperkalemia.
• Volume depletion: correct dehydration before starting therapy to reduce hypotension risk.
• Gout: hydrochlorothiazide may increase uric acid levels.
• Photosensitivity: thiazides may increase skin sensitivity to sunlight.
• Dual RAAS blockade: avoid combination with ACE inhibitors or aliskiren in most cases.

Common:

• Dizziness, headache, fatigue.
• Upper respiratory tract infection, sinusitis.
• Nausea, diarrhea.
• Muscle cramps.

Less common:

• Hypotension, orthostatic hypotension.
• Edema, palpitations.
• Rash, pruritus.

Serious/Rare:

• Acute renal failure.
• Severe electrolyte disturbances.
• Angioedema.
• Severe skin reactions (rare).

• Potassium supplements, potassium-sparing diuretics, salt substitutes: risk of hyperkalemia.
• NSAIDs: may reduce antihypertensive effect and worsen renal function.
• Lithium: increased risk of lithium toxicity; monitor levels.
• Alcohol, barbiturates, narcotics: may enhance orthostatic hypotension.
• Other antihypertensives: additive blood pressure–lowering effect.
• Antidiabetic drugs: thiazides may impair glucose tolerance; dose adjustments may be necessary.
• CYP2C9 inhibitors/inducers: may affect irbesartan levels (usually minimal clinical impact).

• Strengthened pregnancy contraindications with clear guidance to discontinue immediately upon detection.
• Clinical guidelines recommend starting with the lowest dose combination for patients not controlled on monotherapy, and titrating based on tolerance and BP response.
• Continued emphasis on avoiding dual RAAS blockade unless under specialist supervision.

• Store at 20°C–25°C; excursions permitted between 15°C–30°C.
• Protect from moisture and light.
• Keep in original packaging until use.
• Keep out of reach of children.
• No refrigeration required.