Mitoxantrone

Mitoxantrone In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Antitumour antibiotic which inhibits topoisomerase II.
• It is cell cycle non-specific, but most active during the S phase.

Uses of Mitoxantrone

• Treatment of canine and feline lymphoma, squamous cell carcinoma (SCC), and transitional cell carcinoma.

Its use has also been described in:

• Renal adenocarcinoma.
• Ribroid sarcoma.
• Anal gland adenocarcinoma.
• Thyroid carcinoma.
• Prostate carcinoma.
• Mammary gland adenocarcinoma.
• Feline injection site sarcoma.
• Haemangiopericytoma.
• Radiosensitizer in cats with oral SCC.

Dose of Mitoxantrone in Dogs and Cats

Dogs:

• All uses : 5–6 mg/m2 i.v. once every 3 weeks (It should be diluted with up to 50 ml of 0.9% NaCl).
• Intrapleural/intraperitoneal dose: 5 mg/m2 –5.5 mg/m2 diluted in 0.9% NaCl over a 5–10 min period. In one text this is diluted 1:1 in 0.9% NaCl then again in 1 ml per 4.5 kg body weight (it is advised to consult a veterinary oncology specialist before administering via this route).

Cats:

• All uses: 5.5–6.5 mg/m2 i.v. once every 3 weeks. (It should be diluted with up to 50 ml of 0.9% NaCl).

Side Effects of Mitoxantrone in Dogs and Cats

• GI signs (vomiting, anorexia, diarrhoea) and bone marrow depression are the most common signs of toxicity.
• White blood cell counts are generally lowest 10 days after administration.
• Seizure activity in cats has been reported.
• In very rare cases there may be discolouration of the urine and sclera (blue tinge).

Contraindications of Mitoxantrone in Dogs and Cats

• Avoid in patients with myelosuppression, concurrent infection, hepatic disease or impaired cardiac function (although it is likely to be much less cardiotoxic than doxorubicin).
• Cardiotoxicity is not yet reported in dogs and only very rarely reported in humans.

Some Notes:

• Renal excretion is minimal, so it is far safer to administer to cats with renal insufficiency than doxorubicin, although anecdotally acute
• Renal failure in cats can occur following administration.
• Use with extreme caution if administering other myelosuppressive or immunosuppressive agents.
• Chemically incompatible with heparin.