Medication: Methotrexate

Your cat has been prescribed methotrexate to kill certain cancer cells or suppress the immune system.

Key points: 
• Antimetabolite antineoplastic agent.
• Do not handle methotrexate if you are pregnant, breastfeeding, under 18, immunosuppressed or receiving chemotherapy or immunosuppressive drugs.
• Aways wear gloves to handle the tablets/capsules and wash your hands afterwards.
• Never crush or split tablets.
• Cats will excrete chemotherapy products for up to 7 days after administration so precautions must be followed to reduce exposure to other people and pets.
• Dosage: the frequency of dosing varies and should be clearly stated on the packaging provided by your veterinarian. 

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 available information for this medication. If you have other questions or need more information, contact your veterinarian or pharmacist. 

Always follow the dosing instructions provided by your veterinarian. 

Name

• Methotrexate.

Brand name

• There are no licensed veterinary products containing this drug therefore human licensed products may be used extra-label (eg Rheumatrex®, MTX, Amethopterin).

Class of drug

• Antimetabolite antineoplastic agent.

Storage

• Store at room temperature (20°-25° C (68°-77° F)) in a secure container, protected from light.
• Wear gloves when handling and wash hands thoroughly afterwards.
• Can cause birth defects.

Your veterinarian has prescribed methotrexate to treat lymphoma or immune-mediated disease.

Methotrexate is given orally as tablets or by injection by your veterinarian.

Handling methotrexate

• Do not handle methotrexate if you are pregnant, breastfeeding, under 18, immunosuppressed or receiving chemotherapy or immunosuppressive drugs.
• Aways wear gloves to handle the tablets and wash your hands afterwards.
• Never crush or split tablets as it can result in dust which could be dangerous to those around.
• Keep your cat’s drugs in the container supplied. This should be a child proof container.
• Store them in a safe place and always out of the reach of children and pets.
• Methotrexate capsules/tablets are large and cats will easily spit them out if given in food. Give the capsules/tablets directly – they can be washed down with some food or water by syringe afterwards to prevent them getting stuck.
• If you find a tablet or capsule on the floor after administering it to your cat. Wear gloves to pick it up, bag it and dispose of it. Do not give another dose until you have spoken to your veterinarian.
• If you are unable to give oral medication to your cat, please contact your veterinarian for advice.

The following adverse reactions have been noted:

• Gastrointestinal symptoms (common): not eating, nausea, vomiting, diarrhea.
• Changes in feces: dark or tarry feces or fresh blood or mucoid material in the feces (mucosal sloughing).
• Low white blood cell count (leukopenia or neutropenia) – regular blood tests will monitor the white blood cell counts.
• Low platelet counts (thrombocytopenia).
• Low red blood cell counts (anemia).
• Increased liver parameters (hepatotoxicity).
• Increased kidney parameters (nephrotoxicity).

Drug interactions

Many drugs may interact with methotrexate. If your cat is taking other medications or supplements, please check these with your veterinarian before starting treatment.

The following medications may interact with methotrexate:

• Immunosuppressive drugs (eg azathioprine, cyclophosphamide, corticosteroids)
• Ketoconazole
• Phenobarbital
• Loop diuretics
• Cyclosporine
• Other antineoplastics
• Neomycin
• NSAIDs
• Sulfonamides
• Vaccines.

This will depend on the regime provided by your veterinarian.

All unused methotrexate should be returned to your veterinary practice for disposal and must not be placed in household waste.

If you miss a dose, give the dose as soon as possible but do not give a double dose.

Contact your veterinarian immediately if you have given your cat an overdose of methotrexate. It can be highly toxic if an overdose is administered.

Do not administer methotrexate if your pet is unwell – contact your veterinarian for advice.

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

Care must be taken to handle this medication safely:

• Keep in a secure storage area out of reach of children.
• Keep children away from feces, urine, or vomit of treated cats.
• As methotrexate will be present in feces, urine and vomit of cats under treatment, protective gloves must be worn when cleaning up after the treated cat and any feces, urine or vomit and any disposable towels used in the clean up should be disposed in a sealed plastic bag.

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

Handling your cat

The risk of you absorbing any of the toxic products from your cat is small. However, as the risk cannot be quantified, there are some sensible precautions you should take to reduce your exposure during this time.

• Wear gloves when handling any urine, feces, vomit or saliva from your cat.
• Always wash your hands after handling your cat and before eating or drinking.
• The following people should minimize direct contact with your cat:
  • Pregnant or breastfeeding women
  • Young children who do not understand the need for hand washing after contact
  • Immunosuppressed or receiving chemotherapy or immunosuppressive drugs.
• Outdoor cats should be kept indoors for 72 hours after treatment, particularly if they have access into parks or areas where children play.
• Cat litter trays should be lined with plastic litter tray liners and filled with clumping cat litter. This is to prevent contaminated dust.
• Wear gloves when handling the litter tray contents.
• Empty the tray by lifting all the litter out with the liner as soon as possible after soiling to prevent your cat from scratching around in their dirty tray. It may be sensible to use a smaller amount of litter when you refill it during this time. Covered litter trays will restrict the amount of dust that can be spread into the air.
• If your cat has an accident in the house or has soiled itself, you should wear gloves to clean the area as quickly as possible using copious amounts of soapy water. Use disposable paper towels to dry the area and dispose of these in a plastic bag in an outside bin.
• Your cat’s bedding should be washed regularly as some toxic products may end up on your cat’s coat when they lick themselves.
• There is no risk to other pets in the home from sharing water bowls or toileting in the same litter tray.

Your pet will require blood tests to be checked regularly throughout treatment. The frequency will vary depending on the treatment protocol your pet is receiving. Your veterinarian will want to monitor your pet for side-effects and to make sure that treatment is working.

Further information

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

Europe & UK

• There are no licensed veterinary products containing this drug in the UK or Europe. 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 or pharmacist if you have any questions regarding your cat’s medication.