Amlodipine For Cats: Dosage, Safety & Side Effects

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cat in front of a pile of medications

Amlodipine is a common medication used to treat hypertension (high blood pressure) in cats. In this article you’ll learn about amlodipine, how it works, side effects to watch out for, and some frequently asked questions.

Amlodipine For Cats Overview

Medication Type:
Calcium channel blocker anti hypertensive
Form:
Oral tablets
Prescription Required?:
Yes
FDA Approved?:
No. It is important to note that amlodipine does carry a label for use in cats in the UK as the brand Amodip
Brand Names:
Norvasc, approved in the UK for cats as the brand Amodip
Common Names:
Amlodipine
Available Dosages:
Amodip is available in the UK in a 1.25mg chewable tablet. Generic tablets are available as 2.5mg, 5mg, and 10mg size.

About Amlodipine for Cats

Cat high blood pressure can cause sneezing blood

High blood pressure may cause cats to sneeze blood or have nosebleeds.

Amlodipine is a calcium-channel blocker, a type of medication used to control high blood pressure. It is a common first-line drug of choice for treating cats that have high blood pressure.

High blood pressure in a cat is considered to be a medical issue if a systolic blood pressure measurement greater than 160mmHg is repeatedly obtained. A single elevated measurement in conjunction with signs including sudden blindness, collapse, disorientation, seizure-like episodes, weakness, or paralysis also suggests the need for treatment.

What Does Amlodipine Do For Cats?

Causes of high blood pressure in cats

Amlodipine is a dihydropyridine calcium channel blocker.

Amlodipine is a dihydropyridine calcium channel blocker. Calcium channels are ion channels within cells that selectively allow calcium ions. They are present in the cells of most mammals and have a variety of functions within cells, including transmitting signals between cells and the contraction of the muscle.

When amlodipine blocks calcium channels in the smooth muscle of blood vessels, it allows for the blood vessels to dilate, which decreases blood pressure.

Side Effects Of Amlodipine For Cats

cat having its blood pressure checked

Underlying chronic kidney disease can sometimes be a cause of elevated blood pressure and it’s a common practice in these cases to add in a second blood pressure medication.

As with any blood pressure medication which acts to lower blood pressure, lowering it too much, which is called hypotension, is a chief potential side effect. This is why it’s always best to only use amlodipine when and as prescribed by your kitty’s veterinarian.

This is also why it’s very important to keep appointments for rechecking blood pressure at your vet’s office after any changes to a blood pressure medication dosage.

Some digestive upset signs like vomiting, diarrhea, and decreased appetite are uncommonly seen. 

Amlodipine is extensively metabolized by the liver, and so should be used cautiously in any cats with a medical history of liver disease. It should also be used carefully for cats being treated for heart failure.

Underlying chronic kidney disease can sometimes be a cause of elevated blood pressure. There can be some concern when amlodipine is used on its own when the kidney disease is present that it could put a greater strain on the filtration system of the kidneys. It can be common in these cases to add in a second blood pressure medication.

Some remaining infrequent side effects include elevation of kidney values (independent of known pre-existing kidney disease), low potassium, and weight loss. Gum inflammation has apparently been reported but is considered exceedingly rare.

Amlodipine For Cats Dosage

cat taking a medication from a woman's hand

It is not unusual that a second blood pressure medication is prescribed, alongside amlodipine if high blood pressure cannot be fully controlled on amlodipine alone.

Amlodipine should only be started under the care of a veterinarian based on documented elevated blood pressure readings, sometimes in conjunction with signs and symptoms of hypertension. The dosage for amlodipine is typically started at ¼ of a 2.5mg tablet once a day

Adjustments to the dose of amlodipine are only made based on recheck blood pressure measurements at the vet, to ensure that the dosage is catered to the individual needs of your cat.

It can be common to add in a second blood pressure medication if high blood pressure cannot be fully controlled on amlodipine alone. 

Conclusion

What is high blood pressure in cats

Your cat’s blood pressure is influenced by multiple factors, including the heart and blood vessels, along with a complex regulatory system across the entire body.

Amlodipine is a common, first-line choice for a majority of cats suffering from high blood pressure, which can be secondary to a few different disease processes.

It’s always important to only use a blood pressure medication if hypertension and/or related signs of it have been accurately documented. If you feel your cat is exhibiting signs of hypertension and may benefit from a blood pressure medication, make sure to speak with your vet first. 

Frequently Asked Questions

How Quickly Does Amlodipine Work in Cats?

In cats, effects on systemic blood pressure can be seen within 4 hours of it being given. It typically remains effective for about 30 hours, allowing for just once daily dosing. 

Is Amlodipine Safe for Cats?

While it should be used cautiously in certain cases, a majority of cats with high blood pressure do tolerate amlodipine well. 

Because it can take a couple of hours for effects to be seen, sudden, acute side effects in cats after a single dose are uncommon. 

What are the Symptoms of High Blood Pressure in Cats?

The symptoms or clinical signs of feline hypertension can include but are not limited to sudden blindness, collapse, disorientation, seizure-like episodes, weakness, or paralysis. Keep in mind that these signs are not specific for high blood pressure and can be seen with other diseases too.

If your kitty is suffering from any of these signs, it’s always best to have your furry friend examined by your vet to determine what the underlying cause is and what treatment is best. 

Can a Cat Overdose on Amlodipine?

Overdoses of blood pressure medications like amlodipine are possible, which can lead to blood pressure being too low. This happens most often when an additional dose is given at home by accident. This is why it’s very important to have a designated person at home responsible for giving medications to your cat. If multiple family members are involved in administering medications, make sure to keep a schedule or communicate effectively.

Overdoses can also occur if tablets spill out of the bottle and a kitty ingests multiple doses at a time. Always make sure to keep medications in a secure location.

If you have concern your cat may be experiencing an overdose on amlodipine or any other prescription medication, always be sure to contact ASPCA Animal Poison Control (1-888-426-4435) or the Pet Poison Helpline (1-855-764-7661). A fee does apply, but your vet will often need the toxicologist's advice to help develop a treatment plan for your cat.

Avatar photo

About Dr. Chris Vanderhoof, DVM, MPH

Dr. Chris Vanderhoof is a 2013 graduate of the Virginia-Maryland College of Veterinary Medicine (VMCVM) at Virginia Tech, where he also earned a Masters in Public Health. He completed a rotating internship with Red Bank Veterinary Hospital in New Jersey and now works as a general practitioner in the Washington D.C. area. Dr. Vanderhoof is also a copywriter specializing in the animal health field and founder of Paramount Animal Health Writing Solutions, which can be found at www.animalhealthcopywriter.com. Dr. Vanderhoof lives in the Northern Virginia area with his family, including 3 cats.

6 thoughts on “Amlodipine For Cats: Dosage, Safety & Side Effects

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi M, to my knowledge there is no contraindication to using amlodipine with aluminum hydroxide, which is the main ingredient in Phos-Bind and many phosphorus-binding agents. I cannot comment specifically on whether the dosage you mention is appropriate for your cat. While 0.625mg is the low end of the dosage range, this medication should only be used in cats with documented hypertension (high blood pressure) where an attending veterinarian has prescribed it and where a treatment plan exists to recheck blood pressure measurements, ensuring the medication is dosed appropriately.

      Reply
  1. Sarah Sprague

    Whst time of day is best to give amlodipine. My cat is taking methamizole twice daily as he has kidney disease and hyperthyroidism. I give him fluids twice a week. Problem: with amlodipine, he has regurgitated his food twice and I give it at night. Do you think am may be better
    Thanks

    Reply
    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Sarah, thanks for your question. There really isn’t an official best time of day, and can depend on a cat’s habits, needs, and what is seen with the medication.

      If you’re seeing some digestive upset, you may see the same issue regardless of whether it’s given in the morning or evening and may depend more on the proximity to a meal. If you give the medication during the time of a full meal, you may want to try giving it either 30 minutes before eating or an hour following. You could still use a small morsel of food or a treat like a Pill Pocket if that helps with administration.

      The hope is that any effects the medication might have on the meal itself would be lessened by the time lapse. If you can afford to wait an hour after your kitty’s meal in the evening, you could continue doing it in the PM. Otherwise, changing over to the AM would be okay as well.

      If your kitty is free-fed, you could consider pulling up any available food for an hour before or after the medication time and see if this helps.

      Reply
    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Maree,

      While you can see dilated pupils from high blood pressure, this is not something specific for high blood pressure and cats can have dilated pupils at various times of day for a number of reasons, not all of them medical.

      But on the flip side, it is possible to still have a cat that’s hypertensive on amlodipine if the proper dosage has not yet been determined. Having a cat’s blood pressure rechecked after starting any antihypertensive medication and after any dosage changes to verify that blood pressure has normalized is extremely important.

      If you have any concern that your kitty might still have high blood pressure, and especially if this has not been rechecked since starting the medication, since a dosage change, or otherwise at least within the last 6 months, the best thing to do would be to have it checked with your vet and see if the current dose of amlodipine is managing things properly.

      Reply

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