Losartan
Losartan blocks AT1 receptors, but dogs produce little of the potent human metabolite and feline antihypertensive efficacy has not been demonstrated.
Group
Angiotensin II receptor blocker
Mechanism of Action
Blocks angiotensin II effects on vascular AT1 receptors; species-specific metabolism limits clinical response.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Historical renin-angiotensin blockade | 0.125 mg/kg | PO | Every 24 h | Azotaemic patients; reported regimen has limited established efficacy. |
| Historical renin-angiotensin blockade | 0.5 mg/kg | PO | Every 24 h | Nonazotaemic patients; reported regimen has limited established efficacy. |
Indications
- Historical canine renin-angiotensin blockade
Contraindications
- Pregnancy
Interactions
- Combined use with ACE inhibitors may increase renal injury.
Adverse effects
- Hypotension and possible renal or electrolyte effects
Toxicity
Stop excess exposure and monitor blood pressure, renal function and electrolytes.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Losartan 25 mg tablet | Tablet | 25 mg / tablet | PO |
| Losartan 50 mg tablet | Tablet | 50 mg / tablet | PO |
| Losartan 100 mg tablet | Tablet | 100 mg / tablet | PO |
Monitoring and Administration
Monitor blood pressure, renal parameters and potassium.
Consider considering telmisartan or irbesartan instead because losartan has limited canine activity and was not effective in cats.