Dog - Masitinib

Masitinib is an anti-cancer drug used to treat dogs with a certain type of mast cell tumour.  Surgical resection (removal of the tumour) should be used in the first instance for tumours that are operable.  Masitinib is used for severe grade 2 or 3 tumours that cannot be removed by surgery.  Masitinib can only be used for in-operable mast cell tumours in which the tumour cells express the mutated c-kit tyrosine kinase receptor protein.  This must be confirmed before starting treatment.

How does this medicine work?

Masitinib blocks tyrosine kinase enzymes that are found in some receptors on the surface of cells, including c-kit receptor.  Some types of mast cell tumours are linked to a mutation that causes excessive action of c-kit and stimulates the mast cells to divide uncontrollably.  By blocking these receptors, masitinib helps to control cell division, preventing further development of the tumours with this particular mutation.

How do I give this medication?

• Give this medication to your pet as directed by your veterinary surgeon.  READ THE LABEL CAREFULLY.
• Give this medication whole and DO NOT divide, break or crush the tablets.  
• Try to give this medication at about the same time(s) each day and try not to miss giving any doses.
• Wear protective gloves when handling the tablets and also the faeces, urine, or vomit of treated animals.  Wash hands after administering the treatment.  Your veterinary surgeon will advise you on disposal of waste.  In case of accidental ingestion, seek medical advice immediately and show the package, leaflet or label to the physician.
• DO NOT give your pet more medicine than directed and DO NOT give more often than directed.
• DO NOT discontinue the medication without first checking with your veterinary surgeon.  Contact your veterinary surgeon in advance if your pet needs a repeat prescription.

What if I miss giving a dose?

Give the dose as soon as possible.  If it is almost time for the next dose, skip the missed dose, and continue with the regular schedule.  Do not give your pet two doses at once.

How do I store this medicine?

Keep this medicine out of reach of children.  Store this medicine in a cool, dry place at room temperature.  Store away from heat and direct sunlight.  Do not store this medicine in the bathroom, near the kitchen sink or in damp places.  The medicine may break down if exposed to heat or moisture.

Potential side effects

• Although a drug has potential side effects, it does not mean that there is necessarily a high risk of any of these occurring.  Your veterinary surgeon will need to monitor your pet regularly and check certain blood parameters.  Tell your veterinary surgeon if your pet is less than 6 months of age or weighs less than 4 kg.  Tell your veterinary surgeon if you think your pet may be pregnant or is nursing young.
• Masitinib should not be used in dogs with liver or kidney problems, that are anaemic or have a low white blood cell count.
• The following side effects have been reported: vomiting and diarrhoea, and hair loss.  If these symptoms persist and appear troublesome, contact your veterinary surgeon.
• Other side effects may occur.  If you notice anything unusual, contact your veterinary surgeon.

Possible drug interactions

• Make sure to tell your veterinary surgeon what other medication you are giving to your pet.
• Quite often your veterinary surgeon may prescribe two different medications, and a drug interaction may be anticipated.  In this case, your veterinary surgeon may vary the dose and/or monitor your pet more closely.
• Although drug interactions may occur, it does not mean that there is necessarily a high risk of any of these occurring.
• Contact your veterinary surgeon if your pet experiences any unusual reactions when different medications are given together.