Irbesartan

Irbesartan is an angiotensin II receptor blocker (ARB) approved for the following uses across its supported products:

• High blood pressure (hypertension): Both Avapro (film-coated tablet) and Irbesartan tablets are indicated to lower blood pressure, which reduces the risk of fatal and non-fatal stroke and heart attack. Either product may be used alone or in combination with other blood pressure medicines.
• Diabetic nephropathy (kidney disease in type 2 diabetes): Both Avapro and Irbesartan tablets are indicated to slow the progression of kidney disease in adults who have type 2 diabetes, high blood pressure, elevated serum creatinine, and proteinuria (high protein in the urine). In these patients, the medicine reduces the rate at which kidney disease worsens toward end-stage renal disease or the need for dialysis or kidney transplantation.

Irbesartan works by blocking a receptor called AT₁, which is the main target of a hormone called angiotensin II. Angiotensin II is a potent blood vessel constrictor — it tightens vessels, raises blood pressure, and triggers the release of aldosterone (a hormone that causes the body to retain sodium and water). By blocking the AT₁ receptor, irbesartan prevents these effects: blood vessels relax, blood pressure falls, and stress on the kidneys decreases.

Importantly, irbesartan does not inhibit ACE (angiotensin-converting enzyme) or affect bradykinin, which means it typically does not cause the dry cough that is common with ACE inhibitor medicines.

Irbesartan tablets are taken once daily by mouth and can be taken with or without food. Both Avapro and Irbesartan tablets follow this same general schedule. People who are dehydrated or on high-dose diuretics may be started on a lower dose to reduce the risk of dizziness or low blood pressure. Always follow your prescriber's instructions exactly, and do not stop or change your dose without talking to your doctor first.

Most people tolerate irbesartan well. Side effects seen more often than with placebo in clinical trials include:

• Diarrhea
• Indigestion or heartburn
• Fatigue
• Dizziness (more common in patients being treated for diabetic kidney disease)
• Dizziness when standing up quickly (orthostatic dizziness)
• Low blood pressure when standing (orthostatic hypotension)
• High potassium levels (hyperkalemia) — especially in patients with diabetic nephropathy

Seek medical help right away if you notice swelling of the face, lips, tongue, or throat (angioedema), signs of a severe allergic reaction, a dramatic drop in urine output, or symptoms of very high potassium like muscle weakness or irregular heartbeat.

• Fetal toxicity (boxed warning): Irbesartan can cause serious fetal harm or death. Stop taking it as soon as pregnancy is confirmed and contact your doctor immediately. This risk is greatest in the second and third trimesters.
• Low blood pressure (hypotension): People who are dehydrated or salt-depleted — for example, those on aggressive diuretic therapy or on hemodialysis — may develop a dangerous drop in blood pressure when starting irbesartan. Dehydration should be corrected first, or a lower starting dose used.
• Kidney function: Irbesartan can worsen kidney function or cause acute kidney failure, especially in people with renal artery stenosis, chronic kidney disease, severe heart failure, or dehydration. Kidney function should be monitored regularly in these patients.
• High potassium (hyperkalemia): Irbesartan can raise potassium levels. This is a particular concern in patients with diabetic kidney disease or those taking other medicines that also raise potassium.

Irbesartan can interact with several medicines and substance classes. Tell your doctor and pharmacist about everything you take:

• Lithium — irbesartan can increase lithium levels in the blood, raising the risk of lithium toxicity; levels need to be monitored
• Potassium-raising medicines (potassium-sparing diuretics, potassium supplements, potassium-containing salt substitutes) — can cause dangerously high potassium when combined with irbesartan
• NSAIDs and COX-2 inhibitors (ibuprofen, naproxen, celecoxib) — may blunt irbesartan's blood pressure-lowering effect and can worsen kidney function, especially in older adults, dehydrated patients, or those already on diuretics
• Aliskiren — must not be combined with irbesartan in patients with diabetes; should also be avoided in patients with kidney impairment
• Other renin-angiotensin system blockers (ACE inhibitors, other ARBs) — combining these increases risk of low blood pressure, high potassium, and kidney problems without added benefit for most patients

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Pregnancy: Do not take irbesartan if you are pregnant — it can cause serious injury or death to the fetus. Use effective contraception, and stop the medicine immediately if pregnancy occurs.
• Breastfeeding: Irbesartan is not recommended while breastfeeding due to the potential for harm to the nursing infant.
• Diabetes and aliskiren: If you have diabetes, you must not take irbesartan together with aliskiren.
• Kidney disease or renal artery stenosis: Tell your doctor — you may need closer monitoring of kidney function and electrolytes.
• Heart failure or dehydration: You may be at higher risk for low blood pressure or acute kidney failure; your doctor may start you on a lower dose.
• Children: Irbesartan did not appear to effectively lower blood pressure in children ages 6–16 in a clinical study, and it has not been studied at all in children under 6.
• Older adults (65+): No overall differences in safety or effectiveness have been observed, but some older individuals may be more sensitive. No routine dose adjustment is required, but monitoring is wise.
• Hypersensitivity: Do not take irbesartan if you have had an allergic reaction to any component of the product.

If too much irbesartan is taken, the most likely effects are low blood pressure (hypotension) and a fast heartbeat (tachycardia); a slow heartbeat (bradycardia) is also possible. Irbesartan is not removed by dialysis (hemodialysis), so that treatment would not help clear the drug. If you suspect an overdose, contact emergency services or a poison control center right away.

Irbesartan blocks the blood-vessel-tightening effect of angiotensin II, causing blood vessels to relax and blood pressure to fall. A single oral dose produces measurable blockade within hours, and the effect partially lasts for a full 24 hours, which supports once-daily dosing. In patients with high blood pressure, irbesartan does not have meaningful effects on blood fats (triglycerides, cholesterol), blood sugar, uric acid, or kidney filtration rate at recommended doses — an important reassurance for patients who also manage these conditions.

Irbesartan is well absorbed after an oral dose, with 60–80% of the drug reaching the bloodstream; food does not change this. Blood levels peak roughly 1.5 to 2 hours after taking a dose, and the drug's effects last well into the next day (half-life of 11–15 hours), which is why it works with once-daily dosing. It is broken down primarily in the liver by an enzyme called CYP2C9, and about 20% leaves the body through the urine while the rest is eliminated in stool. No dose adjustment is needed for kidney impairment, liver disease (mild to moderate), older age, or sex — though women tend to have slightly higher blood levels than men without any difference in clinical outcome.

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