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CONTRIBUTOR(S): Vetstream Ltd, Julien Bazelle, Rebecca Macmillan, Fear Free,

Medication: Mirtazapine

Medication: Mirtazapine

Your dog may have been prescribed mirtazapine as an appetite stimulant. Mirtazapine also has some anti-nausea properties. It is commonly used in dogs with a decreased appetite due to chronic medical conditions such as kidney disease or anti-cancer chemotherapy. Mirtazapine has also been found to be helpful at managing anxiety in some dogs.

Key points: 
• Tetracyclic antidepressant.
• Appetite stimulant or anti-nausea drug.
• Use with care in dogs with heart, liver or kidney disease.
• Safety not evaluated in pregnant, lactating or breeding dogs.
• Dosage: once daily (dogs).  

This information sheet is designed to help answer commonly asked questions and help you give the medication safely and effectively to your pet. It does not contain all the available information for this medication. If you have other questions or need more information, contact your veterinarian. Always follow the dosing instructions provided by your veterinarian.

Name, Brand names, Class of medication and Storage

Name

  • Mirtazapine (mir-taza-pine).

Brand name

  • There are no licensed veterinary preparations for dogs but feline (Mirataz®) or human (Remeron®, Zispin SolTab) licensed preparations may be prescribed off-label.

Class of drug

  • Tetracyclic antidepressant.

Storage

  • Protect from light and moisture.
  • The coated tablets and the orally disintegrating tablets should be stored at 25°C (77ºF) with excursions permitted to 15-30°C (59-86°F).
  • The stability of the orally disintegrating tablets once removed from the tablet blister is unknown and immediate use is recommended.
  • Store out of sight and reach of children.

Why has my dog been prescribed mirtazapine?

Your veterinarian may have prescribed mirtazapine as an appetite stimulant and/or as an anti-nausea drug. It may also be used to treat anxiety in some dogs.

How is the medication given?

Mirtazapine is usually given orally as tablets, available as 15, 30 and 45 mg tablets (oral disintegrating) and 7.5, 15 and 30 mg tablets (scored film-coated). It can be given with or without food.

Liquid and transdermal forms of mirtazapine may be available, but their use in dogs will depend upon local licensing rules.

Are there any side-effects or drug interactions?

Mirtazapine is generally well-tolerated, and side-effects are rare. Drowsiness is the most common side-effect. Effects on behavior may be seen, such as increased vocalizing.

The following drugs may interact with mirtazapine:

  • Clonidine.
  • Cyproheptadine.
  • Diazepam.
  • Fluvoxamine.
  • Linezolid.
  • Selegiline.
  • Amitraz.
  • Tramadol.
  • Amitriptyline.
  • Cimetidine.
  • Clomipramine.
  • Fluoxetine.

Let your veterinarian know if your dog is taking any other medications including vitamins, supplements and herbal remedies.

How long will my dog need to receive this medication?

Mirtazapine should improve your dog’s symptoms after a day or two and stop working after 24 hours. 

How should I dispose of this medication if I don’t use it all?

Dispose of any unused mirtazapine safely – do not flush down the toilet or sink. Ask your veterinary team if they take back medication for disposal. Do not save mirtazapine for future use or give it to other pets.

What if I miss a dose or give an extra dose?

If you miss a dose, give the dose as soon as possible but do not give a double dose. Make sure the dose given does not exceed the total recommended dose in any 24-hour period.

My dog is unwell, should I still give the drug?

If your pet is unwell, contact your veterinarian for advice.

What should I do if this medication is accidentally given to another pet or taken by a human?

Mirtazapine should only be given to the dog that it has been prescribed for. If accidentally given to other pets, contact your veterinarian for advice.

If accidentally consumed by a human, speak to your primary care physician or poison control center.

Will my dog need to be monitored while on mirtazapine?

Your veterinarian will monitor your dog for side-effects. Regular blood tests may be required.

Further information 

If you have any concerns, further information on mirtazapine can be found on the package insert.

Europe & UK

  • There is a licensed transdermal ointment for use in cats (Mirataz). Its use in dogs will be off-license. Alternatively, your veterinarian may prescribe a human medication containing this drug and will explain off-license use of medications to you.

US

  • There are no licensed veterinary products containing this drug in the US. Your veterinarian may prescribe a human medication containing this drug and will explain off-license use of medications to you.

Always follow the recommended dosage and contact your veterinary team if you have any questions regarding your dog’s medication. 

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