Name
- Doxorubicin.
Class of drug
- Cytotoxic anthracycline antibiotic.
Uses
Action
- DNA intercalation and inhibition of nucleic acid synthesis.
- Free radical formation.
- Topoisomerase inhibition.
Indications
- Lymphosarcoma .
- Hemangiosarcoma.
- Lymphoma, soft tissue sarcomas (including vaccine associated sarcomas) and mammary carcinomas in the cat.
- It may be used alone or in combination with other antineoplastic therapies.
Adverse reactions
Effects of overdosage
Extravasation
- Stop injection, aspirate through needle used for injection. Reported treatment strategies include: application of warm compresses, application of topical DMSO, Dexrazoxane, local injection of corticosteroids and surgical debridement. None of these strategies have proven to be consistently effective.
Other reported reactions
- Severe vesicant if given perivascularity, therefore should be given through well-placed IV catheter. Damage may be severe enough to require amputation.
- Anorexia, vomiting, severe leukopenia, thrombocytopenia, hemorrhagic gastroenteritis and nephrotoxicity (in cats if cumulative dosages exceed 100 mg/m2).
- Allergic reactions have been reported.
- Dose-dependent cumulative cardiotoxicity in dogs (dilated cardiomyopathy and congestive heart failure ). This rarely develops in dogs given a total dose of less than 180-240 mg/m2.
- Tachycardia and arrhythmias on administration but rarely of clinical significance.
Investigation of adverse reaction
- Dogs with pre-existing cardiac disease should not be given doxorubicin or given it very cautiously with risks/benefits considered.
- A complete CBC and platelet count should be monitored whenever therapy is given. If the neutrophil count drops below 3x10³/dl or if the platelet count drops below 150x10³/dl, treatment should be suspended. Once the counts have stabilized doxorubicin can then be restarted at the same dose.
- Monitor renal function in cats during treatment.
- If hematological toxicity occurs again, or if gastrointestinal toxicity is recurrent the dose should be reduced to 1 mg/kg in the cat (20-25 mg/m2 in the dog).
Treatment
Acute anaphylactic reaction- Epinephrine , steroids and fluids.
