Bleomycin
Bleomycin is a glycopeptide antibiotic antineoplastic agent derived from *Streptomyces verticillus*. **Key Clinical Uses:** * Adjunctive treatment for lymphomas, squamous cell carcinomas (SCC), teratomas, and nonfunctional thyroid tumors in dogs and cats. * **Electrochemotherapy (ECT):** Bleomycin is highly effective when combined with intralesional electropermeabilization, significantly increasing intracellular drug concentrations for localized tumors (e.g., feline nasal planum SCC, canine mast cell tumors). **Toxicity Profile:** Unlike many traditional chemotherapeutics, bleomycin is generally **sparing to the bone marrow**. However, it carries significant risks of **pulmonary fibrosis** and dermatologic toxicity. This unique toxicity profile occurs because the lungs and skin lack the enzyme *bleomycin hydrolase*, which normally inactivates the drug in other tissues.
Mecanismo: Bleomycin acts primarily by inducing **single- and double-strand DNA breaks**. * **Mechanism:** The drug possesses a DNA-binding domain and an iron-binding domain. It binds to DNA and chelates intracellular **Fe²⁺** (ferrous iron). * **Oxidative Cleavage:** The Bleomycin-Fe²⁺ complex reacts with oxygen to generate highly reactive oxygen species (ROS), such as superoxide and hydroxyl radicals → oxidative cleavage of the DNA phosphodiester backbone. * **Cell Cycle:** It is considered cell-cycle phase-specific, primarily arresting cells in the **G2 and M phases**. * **Resistance:** Mediated by decreased cellular uptake, increased DNA repair mechanisms, or increased cellular expression of **bleomycin hydrolase** (the enzyme responsible for its degradation).
Dosificación por especie
- Antineoplastic therapy (General guide) · 10 Units mg/m2 (NOT mg/kg) or 0.3-0.5 mg/kg · Parenteral · Varies (e.g., once daily for a few days then once weekly, or once weekly at the start) · Do not exceed total maximum dosage of 125-200 mg/m2 · 1 Unit = 1 mg. Consultation with a veterinary oncologist is strongly recommended.
- Antineoplastic therapy (General guide) · 10 Units mg/m2 (NOT mg/kg) or 0.3-0.5 mg/kg · Parenteral · Varies (e.g., once daily for a few days then once weekly, or once weekly at the start) · Do not exceed total maximum dosage of 125-200 mg/m2 · 1 Unit = 1 mg. Consultation with a veterinary oncologist is strongly recommended.
Las dosis son una referencia clínica para médicos veterinarios. Confirme siempre con la información vigente del producto y el paciente individual.
Vías de administración
Contraindicaciones
- Prior hypersensitivity reactions to the drug
- Preexisting pulmonary disease
- Adverse pulmonary effects from prior therapy
- Pregnancy (unless owners accept the associated teratogenic risks)
Efectos adversos
- Fever
- Anorexia
- Vomiting
- Allergic reactions (including anaphylaxis)
- Alopecia
- Skin rashes
- Stomatitis
- Pneumonitis
- Pulmonary fibrosis (potentially fatal)
- Thrombocytopenia (mild)
- Leukopenia (mild)
- Decreased hemoglobin
- Renal toxicity
- Hepatotoxicity
Interacciones farmacológicas
- General Anesthetics · Bleomycin sensitizes lung tissue to oxygen. Use of general anesthetics can cause rapid deterioration of pulmonary function and post-operative pulmonary fibrosis, even at safe inspired oxygen concentrations.
- Other Chemotherapy Agents or Radiation Therapy · Prior or concomitant use can lead to increased hematologic, mucosal, and pulmonary toxicities.
Monitoreo
- Efficacy (tumor response)
- Pulmonary Toxicity: Chest radiographs (baseline and regularly, e.g., q1-2 weeks), lung auscultation (monitor for dyspnea and fine rales)
- Blood chemistry (renal and hepatic function markers)
- Hematologic profiles (CBC)
- Total cumulative dose accumulation (do not exceed 125-200 mg/m2)
Sobredosis
No specific information was located in the monograph. Because of the high toxicity and low therapeutic index of the drug, it is critical to determine dosages carefully. Overdosage would likely manifest as severe exacerbations of acute toxicities (anaphylaxis, fever, vomiting) and accelerated onset of delayed toxicities (pulmonary fibrosis, stomatitis).
La referencia de fármacos de VetSheet está destinada a médicos veterinarios como apoyo a la decisión clínica; no sustituye el juicio profesional ni la información vigente del fabricante.