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Amlodipine for Veterinary Use

For Veterinary Practices
Prescribe Now
For Pet & Horse Owners
Manage Your Prescriptions

By Evan Ware, DVM

Overview

Therapeutic Class
Calcium channel blocker

Species
Cats and dogs

May Be Prescribed by Veterinarians for:

Cats: Hypertension

Dogs: Hypertension, refractory heart failure

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Basic Information

Amlodipine besylate is classified as a calcium channel blocker medication, and it is effectively used in veterinary medicine to treat hypertension in cats and dogs. The mechanism of action is through the inhibition of calcium entry into smooth muscle cells. Amlodipine has a relative degree of vascular selectivity. It is administered to cats who are also suffering from kidney disease.

Veterinary Medicine Uses for Amlodipine

Amlodipine is used primarily for systemic hypertension in cats and to a lesser extent for heart failure and hypertension in dogs. It can be combined with angiotensin-converting enzyme (ACE) inhibitors, and beta-blockers. Amlodipine slows the rate at which calcium moves into the heart and blood-vessel walls. This enables the blood vessels to relax, which ultimately results in better blood-flow. The effects of amlodipine also make it much easier for the heart to pump blood throughout the body, which lowers the pet's blood pressure.

Amlodipine is well-absorbed orally although the absorption and onset of action takes place over hours. Because of the slow onset of action, hypotension and loss of appetite are not commonly seen with this drug. The oral absorption of amlodipine is not affected by the presence of food. The half-life is thought to be in the range of thirty hours in the dog. Although pharmacokinetic work has not been performed in the cat, in most instances, it is given as a once a day drug.

Amlodipine is considered a very successful first-line treatment for systemic hypertension in cats. Common causes of systemic hypertension in cats include kidney disease, hyperthyroidism, cardiomyopathy, and diabetes. Some clinicians prefer to use amlodipine with ACE-inhibitor drugs in cats with renal disease because of the potential for glomerular damage. Amlodipine therapy has been shown to decrease proteinuria in the majority (69%) of cats with chronic renal disease.

Amlodipine is used to treat dogs with congestive heart failure, mitral valve regurgitation, and systemic hypertension due to chronic renal disease. Systemic arterial hypertension is a frequent complication of chronic renal disease in dogs. ACE inhibitor drugs are usually the drug of choice for hypertension in the dog, and amlodipine is added as needed.

Potential Side-Effects of Amlodipine

Side effects of Amlodipine are quite rare in veterinary medicine, but in some cases, the cat or dog can show lethargy, loss of appetite, weight loss, swelling of the gums or a slight increase in heart rate. It A laceration also can take longer to clot.

Allergic reactions require immediate veterinary attention. Signs of an allergic reaction to Amlodipine include sudden-onset diarrhea, swelling of the face, itching, vomiting, hives, pale gums, cold limbs, or the symptoms of shock or coma.

Drug Interactions with Amlodipine

Although no specific drug-interactions are listed, concomitant use with other drugs that lower blood pressure (diuretics, beta-blockers, and vasodilators) could lead to clinically significant hypotension. Grapefruit juice can alter the bioavailability of amlodipine; the veterinary significance seems minimal.

Precautions for Using Amlodipine

Amlodipine should not be administered to cats or dogs that have liver disease. Female pets that are pregnant or lactating should not be administered the medication. Male and female pets that are breeding also should not receive Amlodipine.

In general, it is recommended that Amlodipine be administered to patients with their food. Treatment should be completed as directed by the prescribing veterinarian to successfully treat the pet's high blood pressure.

Amlodipine depresses conduction velocity and impulse formation in cardiac muscle (negative inotropic). It should be used with caution in animals with heart failure or cardiac shock.

Overdose with calcium channel blockers generally result in profound hypotension and bradycardia. If recognized promptly, gut-emptying protocols can be of value.

Dosage and Administration of Amlodipine

It is important that Amlopipine is given in the manner and frequency prescribed. If a dose is missed, this can cause a sudden rise in the pet's blood pressure. A sudden spike such as this can cause a pet to suffer seizures, kidney damage or blindness. the pet owner should not double the next dose. The pet owner should give the missed dose as soon as possible, but if it is close in time to the next scheduled dose, skip the missed dose and administer the medication again according to the schedule. Two doses should never be given at the same time.

In the case of an accidental overdose immediate veterinary attention is required. Signs of overdose include a very slow heart rate, staggering, dizziness or collapse.

About the Author

Dr. Evan Ware

Dr. Evan Ware is a veterinary practitioner in Phoenix, Arizona. He received both his undergraduate degree in microbiology and his Doctorate of Veterinary Medicine from The Ohio State University.

Dr. Ware is currently the Medical Director of University Animal Hospital (VCA) and is also the owner of two other hospitals, including Laveen Veterinary Center and Phoenix Veterinary Center. His areas of expertise include orthopedic medicine and surgery, veterinary oncology and chemotherapy, and general and advanced soft-tissue surgery.