Irbesartan
Irbesartanum
Also known as: Avalide · Aprovel · Karvea · Arbit · Cavapro · Coaproval · BMS 186295 · SR 47436 · Irbesartanum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| As an alternative to ACE inhibitors for treatment of hypertension associated with renal insufficiency | 5 mg/kg PO q12-24 hours. | PO | q12-24h | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Irbesartan is an Angiotensin-II Receptor Blocker (ARB) primarily used in human medicine to manage hypertension and diabetic nephropathy. In veterinary medicine, its use is currently very limited, but it serves as a potential alternative or adjunct to ACE inhibitors (like enalapril or benazepril) for treating canine hypertension associated with renal insufficiency.
Clinical Pearl: ARBs like irbesartan are often considered when patients experience "ACE escape" (where aldosterone levels rebound despite ACE inhibitor therapy) or when ACE inhibitors are poorly tolerated. Unlike losartan, which requires hepatic conversion to an active metabolite (a process dogs are inefficient at), irbesartan is active in its parent form, making it a more reliable choice for canine patients.
Key Highlights:
- May be useful for hypertension secondary to kidney disease.
- Lacks extensive documentation for heart failure in dogs.
- Strictly contraindicated in pregnancy due to teratogenic effects.
Mechanism of action
Irbesartan selectively and competitively blocks the AT1 (Angiotensin II Type 1) receptor in the Renin-Angiotensin-Aldosterone System (RAAS).
- Pathway: Angiotensinogen → Angiotensin I → Angiotensin II.
- Angiotensin II normally binds to AT1 receptors to cause potent vasoconstriction and stimulate aldosterone release.
- By blocking the AT1 receptor, irbesartan prevents these effects, leading to vasodilation, decreased aldosterone synthesis, reduced potassium excretion, and increased sodium and water excretion.
- Pharmacologic Advantage: It does not inhibit ACE (kininase II), so it does not interfere with bradykinin or substance P responses. Furthermore, it does not require hepatic conversion to an active metabolite, which is a significant pharmacokinetic advantage in dogs compared to losartan.
Safety & warnings
Contraindications
- Pregnancy (teratogenic)
- Nursing/lactating animals
- Hypotension
- Uncorrected volume depletion
- Uncorrected sodium depletion
- Hypersensitivity to irbesartan
Adverse effects
- Diarrhea
- Dyspepsia (indigestion)
- Fatigue or somnolence
- Orthostatic hypotension
- Dizziness
Precautions
Important Warnings:
- Hypovolemia/Hyponatremia: Patients who are volume- or sodium-depleted must have these deficits corrected prior to initiating therapy to avoid acute hypotensive crises.
- Pregnancy Warning: Irbesartan is highly teratogenic (FDA Category D). It causes fetal abnormalities (renal pelvic cavitation, hydroureter) and increased maternal death/spontaneous abortion. Discontinue immediately if pregnancy is detected.
- Hypotension: Do not use in patients with pre-existing hypotension.
Drug interactions
Increased risk of additive hypotension. Use with caution and monitor blood pressure closely.
May exacerbate volume depletion and increase the risk of severe hypotension.
Monitoring
- Systemic blood pressure
- Heart rate
- Serum electrolytes (especially potassium)
- BUN and Creatinine (renal function)
- Clinical signs of adverse effects (GI upset, lethargy, weakness)
Pharmacokinetics
Half-life
Absorption
In humans, absorption is rapid with a bioavailability of 60-80%. Peak levels occur in 1.5-2 hours. Bioavailability is not altered by food.
Distribution
Highly protein-bound (90% in humans). Crosses the blood-brain barrier and placenta in small quantities.
Metabolism
Metabolized in the liver via glucuronidation and oxidation. Metabolites are inactive. Does not require conversion to an active metabolite to exert its effects.
Elimination
Eliminated primarily in the feces (both unchanged drug and metabolites) and to a lesser extent in the urine. Dosage adjustment is not required for renal dysfunction.
Overdose
Toxicity Profile: Irbesartan has a wide margin of safety in acute overdose scenarios. Rats and mice have survived acute oral overdoses exceeding 2000 mg/kg.
Clinical Signs of Overdose:
- Severe hypotension
- Tachycardia (reflex) or bradycardia
Treatment:
- Treatment is largely supportive and symptomatic.
- Address hypotension with intravenous fluids and cardiovascular support as needed.
- Contact an animal poison control center for specific guidance.
Available products
Formulations
- Tablets
Human-labeled
- Irbesartan Tablets: 75 mg, 150 mg, & 300 mg (Avapro)
- Irbesartan 150 mg with Hydrochlorothiazide 12.5 mg Tablets (Avalide)
- Irbesartan 300 mg with Hydrochlorothiazide 12.5 mg or 25 mg Tablets (Avalide)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store tablets at room temperature (15-30°C).
Client information
Guidance for Pet Owners:
- Administration: You may give this medication with food or on an empty stomach. If your pet vomits after taking it on an empty stomach, try giving future doses with a small treat or meal.
- Novel Therapy: Veterinary experience with this drug is currently limited. It is crucial to monitor your pet closely and report any unusual symptoms (such as diarrhea, extreme tiredness, or weakness) to your veterinarian immediately.
- Pregnancy Warning: Do not use in pregnant or nursing animals. This drug can cause severe birth defects or loss of pregnancy. If you suspect your pet is pregnant, contact your veterinarian right away.
- Monitoring: Your veterinarian will likely need to check your pet's blood pressure and perform blood tests periodically to ensure the medication is working safely.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.