Amlodipine
Amlodipine besylate
Also known as: Norvasc · Lotrel (combination) · Caduet (combination) · Amodip · Istin · Amlodipini besilas · UK-48340-26 · UK-48340-11 · Amlodipine maleate · Amlodipine besylate · Amlodipino
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 |
|---|---|---|---|---|---|
| Adjunctive therapy for refractory heart failure (advanced mitral valve degeneration as an afterload reducer) | 0.2-0.4 mg/kg PO twice daily. Initiate therapy at 0.1 mg/kg PO twice daily and up-titrate weekly while monitoring blood pressure. | PO | q12h | — | 🌎 NA |
| Arterial vasodilator for refractory CHF secondary to mitral regurgitation | 0.1 mg/kg q12-24h initially; titrate up as needed to 0.25 mg/kg PO q12-24h | PO | q12-24h | — | 🌎 NA |
| Systemic hypertension in dogs with chronic renal disease | 0.1-0.5 mg/kg PO once daily (q24h) | PO | q24h | — | 🌎 NA |
| Systemic hypertension (2nd step drug) | 0.1 mg/kg q24h; step up to 0.2 mg/kg q24h if needed | PO | q24h | — | 🌎 NA |
| Systemic hypertension | 0.05-0.1 mg/kg (titrate upwards weekly as required, up to 0.5 mg/kg) | PO | q12-24h | Long-term | 🌍 EU |
- Adjunctive therapy for refractory heart failure (advanced mitral valve degeneration as an afterload reducer): After ACE inhibitor maintenance therapy has been established.
- Arterial vasodilator for refractory CHF secondary to mitral regurgitation: Monitor blood pressure.
- Systemic hypertension in dogs with chronic renal disease: Most often combined with an ACE inhibitor. May require weeks to months to achieve satisfactory control.
- Systemic hypertension (2nd step drug): Used after enalapril/benazepril. Each step added if after 1-2 weeks systolic BP > 160 mmHg.
- Systemic hypertension: Monitor blood pressure regularly. Consider concurrent ACE inhibitor.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Systemic hypertension (1st step drug) | 0.625 mg per cat q24h, if cat greater then 6 kg, 1.25 mg/cat q24h | PO | q24h | — | 🌎 NA |
| Systemic hypertension | 0.625-1.25 mg (total dose) PO once daily | PO | q24h | — | 🌎 NA |
| Systemic hypertension | 0.625-1.25 mg/cat | PO | q24h (may increase slowly or increase frequency to q12h if necessary) | Long-term | 🌍 EU |
- Systemic hypertension (1st step drug): Add ACE inhibitor if proteinuric.
- Systemic hypertension: Drug of choice; often successful as a single agent. Maximum effect seen within 7 days.
- Systemic hypertension: Blood pressure monitoring is essential. Appears safe even with concurrent renal failure.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Amlodipine is a dihydropyridine calcium channel blocker (CCB) primarily utilized in veterinary medicine as a potent peripheral arterial vasodilator.
- Feline Medicine: It is considered the gold standard and first-line therapy for managing feline systemic hypertension, which is often secondary to chronic kidney disease (CKD), hyperthyroidism, or hypertrophic cardiomyopathy. It is highly effective as a single agent in cats.
- Canine Medicine: In dogs, it is typically used as an adjunctive afterload reducer in refractory congestive heart failure (CHF) or as a second-line antihypertensive agent. When used alone in dogs at higher doses, it can activate the renin-angiotensin-aldosterone system (RAAS), so it is frequently combined with an ACE inhibitor (e.g., enalapril) to mitigate this effect.
- Clinical Pearl: It has a relatively slow onset of action, which helps prevent acute hypotensive crises, but missing doses can lead to rapid rebound hypertension.
Mechanism of action
Amlodipine selectively inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle by blocking L-type voltage-gated calcium channels.
- Vascular Smooth Muscle → Relaxation and vasodilation → Significant reduction in peripheral vascular resistance (afterload) → Decreased systemic blood pressure.
- It has a much higher affinity for vascular smooth muscle than cardiac muscle, meaning it produces profound vasodilation with minimal negative inotropic (contractility) or chronotropic (heart rate) effects at therapeutic doses.
- Cardiac Muscle → Mildly depresses impulse formation (automaticity) and conduction velocity.
Safety & warnings
Contraindications
- Patients with cardiogenic shock
- Advanced aortic stenosis (relative contraindication)
- Use with caution in patients with heart failure (due to slight negative inotropic effects)
- Use with caution in patients with hepatic dysfunction
Adverse effects
- Cats: Infrequent azotemia, lethargy, hypokalemia, reflex tachycardia, weight loss
- Dogs: Gingival hyperplasia (with long-term use)
- Anorexia and hypotension (early in therapy)
Precautions
Renal Considerations in Cats: There is concern that using amlodipine alone for treating hypertension in cats with renal disease may expose glomeruli to higher pressures secondary to efferent arteriolar constriction (caused by localized RAAS activation). Using an ACE inhibitor concurrently may help prevent this, though routine use of ACE inhibitors with amlodipine in cats with CKD remains somewhat controversial.
- Cardiac Disease: Use cautiously in patients with heart failure due to slight negative inotropic effects.
- Hepatic Disease: Use cautiously as the drug is extensively metabolized in the liver; half-life may be prolonged.
- Pregnancy: Fetotoxic in laboratory animals at very high doses; prolonged labor in rats. FDA Category C.
Drug interactions
Concomitant use may cause additive hypotension.
Concomitant use may cause additive hypotension.
Concomitant use may cause additive hypotension.
May cause hypotension if used concurrently.
May alter bioavailability of amlodipine.
May impair hepatic metabolism of amlodipine, increasing circulating levels
May impair hepatic metabolism of amlodipine, increasing circulating levels
May impair hepatic metabolism of amlodipine, increasing circulating levels
May impair hepatic metabolism of amlodipine, increasing circulating levels
CYP3A4 inducer; may reduce circulating amlodipine levels
Increased risk of hypotension when combined
Monitoring
- Systemic blood pressure (frequent monitoring during dose titration)
- Ophthalmic exam (to assess for hypertensive retinopathy/retinal detachment)
- Renal values and electrolytes (especially if combined with ACE inhibitors)
- Clinical signs of hypotension (lethargy, weakness)
Pharmacokinetics
Half-life
Absorption
Slowly but almost completely absorbed after oral administration. Bioavailability is not altered by food.
Distribution
Very high plasma protein binding characteristics (approximately 93%).
Metabolism
Slowly but extensively metabolized to inactive compounds in the liver.
Elimination
Hepatic metabolism and subsequent excretion.
Overdose
Overdoses pose a significant risk for profound hypotension and reflex tachycardia (though bradycardia is also possible). Common clinical signs in dogs and cats include lethargy and vomiting.
Treatment:
- When possible, massive overdoses should be managed with gut emptying (emesis/lavage) and activated charcoal.
- Provide aggressive supportive treatment (IV fluids).
- Specific therapies may include beta-agonists, intravenous lipid emulsion (ILE) therapy, and intravenous calcium to counteract the calcium channel blockade.
Available products
Formulations
- Oral tablets
- Oral suspension (compounded)
Human-labeled
- Amlodipine Oral Tablets: 2.5 mg, 5 mg, & 10 mg (Norvasc, generic)
- Fixed-dose combination products with benazepril (Lotrel) or atorvastatin (Caduet)
Regulatory status
Amodip is approved for cats in the EU.
POM-V, POM.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store tablets at room temperature in tight, light-resistant containers. Compounded oral suspensions (1 mg/mL in Ora-Plus/Ora-Sweet) retain >90% potency for 91 days at 5°C and 25°C, but must be protected from light.
Client information
- Administration: May be given with or without food.
- Consistency is Key: High blood pressure is a "silent killer." Missing dosages can cause a rapid redevelopment of hypertension, which may lead to acute blindness, seizures, or severe kidney damage.
- Monitoring: Regular veterinary visits are required to measure your pet's blood pressure and ensure the dose is correct.
- Side Effects: Watch for signs of lethargy, weakness, or loss of appetite, especially when starting the medication. In dogs, long-term use may cause the gums to overgrow (gingival hyperplasia).
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.