ブレオマイシン
ブレオマイシンは、*Streptomyces verticillus*に由来する糖ペプチド系の抗腫瘍性抗生物質です。 **主な臨床用途:** * 犬および猫のリンパ腫、扁平上皮癌（SCC）、奇形腫、非機能性甲状腺腫瘍の補助治療。 * **電気化学療法（ECT）:** 病変内電気穿孔法と組み合わせることで非常に効果的であり、局所腫瘍（猫の鼻鏡扁平上皮癌、犬の肥満細胞腫など）の細胞内薬物濃度を著しく高めます。 **毒性の特徴:** 多くの従来の化学療法薬とは異なり、ブレオマイシンは通常**骨髄抑制をほとんど起こしません**。しかし、**肺線維症**や皮膚毒性の重大なリスクを伴います。この特有の毒性プロファイルは、肺や皮膚には薬物を不活性化する酵素である*ブレオマイシン水解酵素*が不足しているために起こります。
作用機序: 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).
動物種別の用量
- 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.
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Prior hypersensitivity reactions to the drug
- Preexisting pulmonary disease
- Adverse pulmonary effects from prior therapy
- Pregnancy (unless owners accept the associated teratogenic risks)
有害事象
- 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
薬物相互作用
- 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.
モニタリング
- 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)
過量投与
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).
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。