Lomustine (CCNU)

Lomustine (CCNU) In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Interferes with the synthesis and function of DNA, RNA and proteins.
• Antitumour activity correlates best with formation of interstrand cross-linking of DNA.
• Lomustine is highly lipid-soluble, allowing rapid transport across the blood–brain barrier.

Uses of Lomustine (CCNU)

• Reported to have some efficacy in the treatment of brain tumours, mast cell tumours, refractory lymphoma, histiocytic sarcoma and epitheliotrophic lymphoma.
• Component of the modified CHOP protocol for treatment of T-cell lymphoma.

Dose of Lomustine (CCNU) in Dogs and Cats

Dogs:

• All uses: 60–80 mg/m2 p.o. q3–4wk.

Cats:

• All uses: A dose of 30–60 mg/m2 p.o. q4–6wk has been suggested but is not well established.
• If using this drug in the cat, specialist advice should be sought, as dosing intervals may need to be increased.

Side Effects of Lomustine (CCNU) in Dogs and Cats

• Myelosuppression is the dose-limiting toxicity, with neutropenia developing 7–14 days after administration (although the onset of myelosuppression can range from 1–6 weeks and can be particularly delayed in cats).
• Neutropenia may be severe and life-threatening at the higher end of the dose range in some dogs.
• Thrombocytopenia can also be seen, often with no other concurrent cytopenias.
• GI and cumulative dose-related and potentially irreversible hepatic toxicity have been reported in the dog.

Contraindications of Lomustine (CCNU) in Dogs and Cats

• Bone marrow suppression.
• Pre-existing liver disease.

Some Notes:

• Do not use it with other myelosuppressive agents.
• Lomustine requires hepatic microsomal enzyme hydroxylation for the production of antineoplastic metabolites.
• It should be used with caution in dogs being treated with agents that induce liver enzyme activity, e.g. phenobarbital.
• In humans, cimetidine enhances the toxicity of lomustine.