Mirtazapine is a prescription appetite stimulant commonly used in veterinary medicine in cats to stimulate interest in food and eating and to promote weight gain.
Brands include Remeron and Mirataz. In this article, you will learn what mirtazapine is, how it works, the different dosage forms available, potential side effects to monitor for, and some common questions.
Overview of Mirtazapine for Felines
5-HT3 (serotonin) receptor antagonists and tetracyclic antidepressants
Oral tablet, topical transdermal ointment
Do I need a prescription? :
About the topical transdermal ointment Mirataz is FDA-approved for use in cats.
The safety study of Mirataz in cats included cats as young as 7-10 months of age.
Mirataz transdermal ointment: 100mg/tube in a 5g tube (20mg/g); oral tablets: 7.5mg, 15mg, 30mg and 45mg.
About mirtazapine for cats
Mirtazapine is classified as a serotonin receptor antagonist and a tetracyclic antidepressant. In cats, however, it is used less as a behavioral drug and more for the benefits of promoting appetite and eating.
Norepinephrine (NE) is a neurotransmitter that, among many other things, does act on certain receptors in the body to increase appetite. Mirtazapine is thought to block the receptors that prevent the release of NE. This results in an increase in NE followed by an increase in appetite.
Mirtazapine also blocks serotonin receptors. By blocking certain serotonin receptors, mirtazapine also provides antiemetic and antiemetic (anti-emetic) effects.
Currently, mirtazapine is marketed as a generic tablet and under the topical transdermal brand Mirataz, which is applied to the skin on the inner surface of the ear flap.
What does mirtazapine do in cats?
Veterinarians have used mirtazapine for years to help stimulate appetite in cats. This may apply to cats with poor appetites, such as kittens with chronic kidney disease (CKD), or cats with other medical conditions that cause weight loss, where we want to encourage greater calorie intake.
Mirtazapine side effects in cats
Mirtazapine is generally well tolerated in cats, but some adverse effects require attention and monitoring.
Since mirtazapine does also act as a histamine blocker, sedating effects may occur, especially at higher doses.
The next most common side effect is increased vocalization, seen in approximately 50% of cats. Gastrointestinal effects such as irritability and vomiting may occur in approximately 25% to 33% of cats.
Abnormal walking, restlessness/hyperactivity, and excessive salivation (drooling) may occur in slightly more than 10% of cats. The remaining side effects affecting only about 10% or fewer cats may include increased breathing and heart rate, loss of appetite, disorientation, inappropriate excretion, trembling/shivering and hiding behavior, etc.
Studies looking at the use of mirtazapine in cats found fewer adverse effects when lower doses were used.
Specifically, for the topical brand Mirataz, approximately 10% of cats may experience a reaction at the application site on the inner surface of the pinna. This may include, but is not limited to, redness, crusting, crusting, and residue buildup.
In reports to the ASPCA Animal Poison Control Center, the most common signs of overdose include excessive vocalization, agitation, and vomiting. Fortunately, at least in humans, doses 10 to 30 times over the prescribed dose showed minimal toxicity, requiring only a few hours of observation.
Mirtazapine can interact with many different medicines, especially sedatives, pain medicines, and medicines used to modify behavior. If mirtazapine is recommended or prescribed, be sure to discuss with your veterinarian any medications your kitten may be taking.
Mirtazapine should be used with caution in pets with kidney disease, liver disease, heart disease, or diabetes. Mirtazapine is usually used for certain conditions that affect appetite, but the dose may need to be lowered and monitored more carefully.
If you are concerned that your kitten may experience side effects from mirtazapine, be sure to contact your veterinarian, the ASPCA Animal Poison Control Center (1-888-426-4435) or the Pet Poison Helpline (1-855-764) -7661) for further advice.
Mirtazapine Dosage for Cats
Doses of mirtazapine tablets range from approximately 2 mg to 3.75 mg, depending on goals and tolerance for side effects. Generic tablets are only available in 7.5 mg and 15 mg.
Dosing frequency for oral tablets may only need to be every 48 to 72 hours, but the cat’s appetite should be carefully monitored to determine the optimal dosing interval.
Since the proper dosage and frequency may depend largely on your cat’s needs and any current medical conditions, be sure to first discuss your kitten’s mirtazapine dosage, both current and past, with your veterinarian Health status.
The topical product Mirataz, an FDA-approved mirtazapine transdermal ointment for weight loss control in cats, was applied to the inner pinna (flap) of the ear every 24 hours for 14 days at the indicated dose of a 1.5-inch strip of the ointment. This corresponds to a dose of about 2 mg.
When using Mirataz, it is very important that the person applying the product wear gloves to prevent absorption of the product into their own skin. It is best to use the thumb or forefinger to properly apply the product to the inner surface of the pinna, but as a transdermal product, the medication may be absorbed through the skin of the person applying the product.
Although mirtazapine is also a drug that is sometimes used in humans, accidental absorption of this product should still be avoided.
Mirtazapine is an excellent medication that can help support kittens who are suffering from weight loss or loss of appetite. The topical brand Mirataz could also offer a popular route of administration for kittens who already don’t eat well or have difficulty taking their medications orally.
Due to its activity as an antidepressant, some side effects may occur with mirtazapine. However, in most cats, especially those given lower doses, mirtazapine is generally well tolerated and is a very useful treatment.
frequently asked questions
What does mirtazapine do in cats?
Mirtazapine is an appetite-stimulating drug. It is most commonly used in cats suffering from short-term or long-term loss of appetite as well as weight loss.
How long does mirtazapine last in cats?
This usually depends on the dosage and form. The oral tablet lasts about 48 hours on average, but may last shorter and closer to 24 hours in some cats, and up to 72 hours in others.
Does mirtazapine make cats sleepy?
Because one of the effects of mirtazapine is to act as a histamine blocker, it can produce a sedative effect. This has a similar effect to other medications that we think of as more like antihistamines for allergies, such as diphenhydramine. This effect of mirtazapine is usually more pronounced when higher doses are used, such as doses approaching 3.75 mg or higher.
How much mirtazapine can you give your cat?
The indicated dose of Mirataz, a topical product, is a 1.5-inch strip of ointment applied to the skin of the pinna (flap) inside the ear. This dose is equivalent to 2 mg of the drug.
Mirtazapine tablets range in dosage from about 2 mg to 3.75 mg, and cats are usually given every 24 to every 72 hours. Which dosage is right for your cat will largely depend on the conditions causing the loss of appetite and/or weight loss, as well as other conditions your kitten may have.
Higher doses and more frequency may have more side effects, so it is always very important to discuss the dosage and frequency of mirtazapine with your veterinarian before giving your cat a dose.
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