Vet Guide to Amlodipine Besylate in 2025 🐾

Hi, I’m Dr Duncan Houston, BVSc, founder of Ask A Vet. In this comprehensive guide, we dive into everything you need to know about amlodipine besylate—how it works, species-specific dosing, potential side effects, drug interactions, and monitoring protocols to keep your pet safe and thriving. Let’s explore! 🩺

📘 What Is Amlodipine?

Amlodipine is a long-acting dihydropyridine calcium-channel blocker, commonly prescribed off-label by veterinarians to treat systemic hypertension in dogs and cats :contentReference[oaicite:3]{index=3}. It’s FDA-approved for humans (brand names like Norvasc®), but used extra-label in veterinary medicine :contentReference[oaicite:4]{index=4}.

🔬 How It Works

By blocking calcium entry into smooth muscle cells of blood vessels and the heart, amlodipine relaxes arteries and lowers blood pressure. It also mildly affects cardiac function, so it’s used cautiously in pets with heart disease :contentReference[oaicite:5]{index=5}.

✅ Common Veterinary Uses

• Systemic hypertension—cats (CKD, hyperthyroidism, cardiomyopathy) and dogs (CKD, diabetes, pheochromocytoma) :contentReference[oaicite:6]{index=6}.
• Supportive treatment in canine congestive heart failure and mitral valve disease :contentReference[oaicite:7]{index=7}.

📐 Dosing & Administration

Dogs

• Typical starting dose: 0.1–0.2 mg/kg orally once daily, up to 0.4 mg/kg daily or split twice daily based on response :contentReference[oaicite:8]{index=8}.
• Begin at 0.05–0.1 mg/kg and titrate with blood pressure monitoring :contentReference[oaicite:9]{index=9}.

Cats

• Generally: 0.625–1.25 mg per cat once daily, or 0.125–0.25 mg/kg daily; some require up to 2.5 mg/day :contentReference[oaicite:10]{index=10}.
• Reassess blood pressure in 3–5 days to adjust dose :contentReference[oaicite:11]{index=11}.

📋 How to Give

• Can be given with or without food. Administer with meals if GI upset occurs :contentReference[oaicite:12]{index=12}.
• Liquid formulations and compounded preparations are available for accurate dosing, especially in cats or small dogs :contentReference[oaicite:13]{index=13}.
• Do not skip doses—missing doses can lead to sudden blood pressure spikes :contentReference[oaicite:14]{index=14}.

⚠️ Side Effects & Precautions

• **Common**: vomiting, diarrhea, decreased appetite, lethargy :contentReference[oaicite:15]{index=15}.
• **Dogs** may develop gum overgrowth (gingival hyperplasia) :contentReference[oaicite:16]{index=16}.
• **Serious but rare**: hypotension (collapse, weakness), bradycardia/tachycardia, limb swelling, bleeding abnormalities :contentReference[oaicite:17]{index=17}.
• **Side effect triggers**: use caution in hypovolemic pets, those in shock, liver failure, or aortic stenosis :contentReference[oaicite:18]{index=18}.

🔗 Drug Interactions

Amlodipine is metabolized via CYP3A4 and may interact with other BP meds like ACE inhibitors, diuretics, beta-blockers, and CYP3A4 inhibitors (e.g., azole antifungals, diltiazem). Tell your vet about all medications, supplements, and herbal products :contentReference[oaicite:19]{index=19}.

🩺 Monitoring & Follow-Up

• Check blood pressure 3–7 days after starting or adjusting dose; repeat every 6–12 months once stable :contentReference[oaicite:20]{index=20}.
• Monitor appetite, energy, urination, and mobility.
• Consider kidney/liver panels as amlodipine is metabolized hepatically and excreted renally :contentReference[oaicite:21]{index=21}.
• For systemic hypertension: check eye exams (retinas), heart function, and kidney status to watch for “target organ damage.” :contentReference[oaicite:22]{index=22}.

🕐 Onset & Duration

Effects begin within 1–2 hours and peak around 4–6 hours in dogs; in cats, improvements usually seen within a few hours :contentReference[oaicite:23]{index=23}. It has a long duration (~24 hrs), allowing once-daily dosing :contentReference[oaicite:24]{index=24}.

💊 Missed Dose?

Give as soon as you remember unless the next dose is due soon. Never double spike the dose. If in doubt, ask your vet :contentReference[oaicite:25]{index=25}.

🚨 Overdose & Emergency Care

Overdose may cause severe hypotension, bradycardia, collapse, tremors, seizures. If suspected, seek emergency vet care or call Pet Poison Helpline at 855‑764‑7661. Treatment may include IV fluids, atropine, and vasopressors :contentReference[oaicite:26]{index=26}.

🏡 Real‑World Treatment Scenarios

🐱 Senior Cat with CKD & High BP

• Start 0.625 mg once daily; recheck BP in 5 days.
• If still >160 mmHg, increase to 1.25 mg/day; monitor kidney values.
• Add ACE inhibitor (like benazepril) or switch to telmisartan if response is inadequate :contentReference[oaicite:27]{index=27}.

🐶 Dog with Hypertension & Heart Valve Disease

• Begin 0.1 mg/kg daily; monitor BP and heart rate after 1 week.
• If BP remains elevated, increase to 0.2 mg/kg or add ACE inhibitor.
• Watch for gum changes; manage with dental care if needed.

❓ FAQs

Is amlodipine a diuretic?

No, it's a calcium-channel blocker. It may have mild diuretic effect but is not a true diuretic :contentReference[oaicite:28]{index=28}.

Can I crush tablets for my cat?

Ask your vet—liquid formulations or compounded meds may be easier. Crushing tablets may have an unpleasant taste :contentReference[oaicite:29]{index=29}.

Why does my pet need blood work?

To ensure kidneys, liver, and other organs remain healthy—and to catch any adverse effects early.

Can I stop it when BP is normal?

Hypertension is usually chronic—don’t stop without vet guidance and BP rechecks.

📌 Final Takeaways

• Amlodipine is a trusted, long-acting BP medication used off-label in pets—especially cats—and safe when dosed and monitored correctly.
• Doses begin at 0.1–0.2 mg/kg for dogs and 0.625–1.25 mg per cat daily, adjusted per BP response.
• Side effects are usually mild but may include GI upset, lethargy, low BP, and gum overgrowth.
• Regular BP monitoring, physical exams, and periodic blood tests are essential.
• Interact cautiously with other medications; always communicate with your vet.

Need help managing hypertension in your dog or cat? Ask A Vet is here 24/7 to support you with tailored protocols and personalized veterinary care. Download the Ask A Vet app now for peace of mind and optimal pet health. 🐾❤️