Bleomycin Sulfate — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	IV	10-20 mg/m²	q24h for 3-5 days, then weekly	Duration: Variable; typically 4-6 cycles Notes: Monitor for pulmonary toxicity; cumulative dose should not exceed 200 mg/m².
Cat	IV	10-20 mg/m²	q24h for 3-5 days, then weekly	Duration: Variable; typically 4-6 cycles Notes: Cats may be more sensitive to pulmonary toxicity; use lower end of dose range.
Horse	Intralesional	1-5 mg per lesion	q2-4 weeks	Duration: Until resolution Notes: For sarcoids and squamous cell carcinoma; may be combined with surgical debulking.
Horse	IV	10-20 mg/m²	q24h for 3-5 days, then weekly	Duration: Variable Notes: Use with caution; monitor for pulmonary toxicity.
Rabbit	SC or IV	10-15 mg/m²	q24h for 3-5 days, then weekly	Duration: Variable Notes: Limited data; use with caution.
Exotic (Reptiles)	IM or SC	0.5-1 mg/kg	q24h for 3-5 days, then weekly	Duration: Variable Notes: Limited data; adjust based on species and response.

Clinical Indications & Species Uses

General Indications

Antineoplastic agent for various tumors, especially squamous cell carcinoma and lymphoma

Dog (Canine)

Squamous cell carcinoma
Lymphoma (as part of combination protocols)
Mast cell tumors (rescue therapy)
Testicular tumors
Malignant effusions (intracavitary administration)

Cat (Feline)

Squamous cell carcinoma (especially oral)
Lymphoma (as part of combination protocols)
Mammary carcinoma (palliative)
Injection-site sarcoma (adjunctive therapy)

Horse (Equine)

Squamous cell carcinoma (ocular, cutaneous)
Sarcoids (intralesional therapy)

Rabbit & Small Mammals

Squamous cell carcinoma (cutaneous, oral)
Uterine adenocarcinoma (palliative)

Exotic & Other Species

Reptiles: squamous cell carcinoma (reported)
Ferret: lymphoma (limited reports)

Pharmacology & Mechanism of Action

Drug Class: Antineoplastic antibiotic | Pharmacological Group: Glycopeptide antitumor antibiotic

Mechanism of Action: Bleomycin sulfate is a glycopeptide antibiotic that exerts its cytotoxic effects by causing single- and double-strand breaks in DNA. It requires a metal ion (e.g., Fe2+) and oxygen to form a complex that generates reactive oxygen species, leading to DNA fragmentation. The drug is cell cycle-specific, primarily acting in the G2 phase and M phase, and it also inhibits DNA synthesis. It has minimal myelosuppressive activity compared to other chemotherapeutic agents.

Pharmacodynamics: Bleomycin is cytotoxic to both dividing and non-dividing cells, but its effects are most pronounced in rapidly proliferating tissues. It is particularly effective against squamous cell carcinomas and lymphomas. The drug's activity is cell cycle-specific, with cells in G2 phase being most sensitive. It also induces apoptosis in susceptible cells. The lack of significant bone marrow suppression makes it useful in combination regimens where myelosuppression is a concern.

⚡ Pharmacokinetics Summary

Absorption: Bleomycin is not absorbed orally and must be administered parenterally (IV, IM, SC, or intracavitary). After parenteral administration, absorption is rapid and complete.

Distribution: Bleomycin distributes widely in the body, with highest concentrations in skin, lungs, kidneys, peritoneum, and lymph nodes. It does not cross the blood-brain barrier significantly. Protein binding is low (approximately 1%).

Metabolism: Bleomycin is metabolized by the enzyme bleomycin hydrolase, which is found in most tissues except the skin and lungs. This explains the drug's toxicity to these organs, as they have low enzyme activity.

Excretion: The drug is primarily excreted unchanged in the urine via glomerular filtration. In patients with normal renal function, approximately 60-70% of the dose is excreted within 24 hours. Renal impairment can lead to increased toxicity.

Half-Life: The elimination half-life is approximately 2-4 hours in dogs and cats with normal renal function, but may be prolonged in patients with renal insufficiency.

Bioavailability: Not orally bioavailable; parenteral administration required.

Protein Binding: Low (approximately 1%)

Available Formulations & Strengths

Injectable Solution (powder for reconstitution) 15 units (15 mg) per vial (IV, IM, SC, Intralesional, Intracavitary)

Contraindications & Clinical Warnings

Contraindications:

Hypersensitivity to bleomycin
Severe pulmonary disease
Severe renal impairment (dose adjustment required)
Pregnancy (teratogenic)
Lactation (do not use in nursing animals)

Warnings & Clinical Precautions:

Pulmonary toxicity is dose-limiting; monitor for cough, dyspnea, and pulmonary infiltrates.
Renal function should be assessed before and during therapy; dose reduction in renal impairment.
Extravasation may cause tissue necrosis; administer IV carefully.
Immunosuppression may occur; monitor for infections.
Use with caution in animals with pre-existing lung disease.
Bleomycin is a vesicant; handle with protective equipment.
Fertility may be impaired; advise owners of breeding animals.

Adverse Effects & Reactions

Common:

Fever
Nausea/vomiting (less common in animals)
Alopecia (especially in dogs)
Hyperpigmentation of skin
Mucositis

Serious / Severe:

Pulmonary fibrosis (dose-limiting)
Interstitial pneumonitis
Anaphylaxis (rare but severe)
Renal toxicity (with high doses)
Myelosuppression (mild, but may occur)

Rare:

Hepatotoxicity
Cardiotoxicity
Erythema multiforme
Raynaud's phenomenon (in humans; rare in animals)

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Cisplatin	Increased risk of pulmonary toxicity; avoid concurrent use.	High
Oxygen	High inspired oxygen concentrations may increase pulmonary toxicity; avoid hyperoxia during and after therapy.	High
Nephrotoxic drugs (e.g., aminoglycosides, NSAIDs)	Additive renal toxicity; monitor renal function.	Moderate
Other chemotherapeutic agents	Additive immunosuppression and toxicity; adjust doses accordingly.	Moderate
Digoxin	Bleomycin may decrease digoxin absorption; monitor digoxin levels.	Mild

Overdose & Toxicity Management

Signs of Toxicity:

Severe pulmonary toxicity
Fever
Hypotension
Renal failure
Mucositis
Myelosuppression

Emergency Treatment Protocol: There is no specific antidote. Treatment is supportive and symptomatic. Monitor respiratory function closely; administer oxygen if needed but avoid hyperoxia. Consider corticosteroids for pulmonary inflammation (controversial). Provide IV fluids for hydration and renal support. In severe cases, mechanical ventilation may be required. Discontinue drug immediately.

Food Animal Withdrawal Times

🥩 Meat: 30 days🥛 Milk: 7 days

Not approved for food animals; withdrawal times are extrapolated and not established. Use in food animals is off-label and requires veterinary oversight; ensure adequate withdrawal periods to avoid residues.

Storage, Handling & Regulatory Information

Storage Temperature: Store powder at 2-8°C (refrigerate) and protect from light. Reconstituted solution is stable for 24 hours at room temperature or 48 hours under refrigeration.

Light Sensitivity: Light-sensitive — protect from direct exposure.

Handling & Special Conditions: Reconstituted solution should be used within 24 hours; discard unused portion. Protect from light.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; approved for human use. Veterinary use is extra-label.

Extra-Label (Off-Label) Use: Bleomycin is not approved for veterinary use in most countries; use is extra-label. In the US, extra-label use in food animals is prohibited unless under AMDUCA with a valid VCPR and withdrawal times are extended. In companion animals, use is accepted but requires informed owner consent.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Bleomycin is a valuable chemotherapeutic agent for treating squamous cell carcinomas and lymphomas in veterinary patients, particularly when myelosuppression is a concern. Its dose-limiting toxicity is pulmonary fibrosis, which can be fatal; therefore, cumulative doses should be kept below 200 mg/m² and patients should be monitored for respiratory signs. Renal function should be assessed before each dose, and dose adjustments are necessary in patients with renal impairment. Because bleomycin is a vesicant, careful IV administration is essential to prevent extravasation. In horses, intralesional administration is effective for sarcoids and ocular squamous cell carcinoma. In exotic pets, use is based on limited evidence and should be guided by a specialist. Always use appropriate personal protective equipment when handling the drug. Combination protocols may enhance efficacy but increase toxicity; consult a veterinary oncologist for optimal protocols.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)