フィルグラスチム
**フィルグラスチム**は、獣医療において骨髄を刺激して好中球を産生させるために使用される遺伝子組換えヒト顆粒球コロニー刺激因子（G-CSF）です。 重要な臨床的ポイント： * **主な適応：** 重度で生命を脅かす好中球減少症（例：パルボウイルス感染症、化学療法による骨髄抑制、猫白血病ウイルス関連の周期性好中球減少症など）に使用されます。 * **免疫原性のリスク：** ヒトDNA由来であるため、犬や猫に対して**高い免疫原性**を示す可能性があります。患者は外因性の薬剤だけでなく、自己のG-CSFに対する中和抗体を産生する可能性があり、その結果、重度で長期にわたる致命的な好中球減少症を引き起こす恐れがあります。 * **臨床戦略：** 抗体産生を最小限に抑えるため、通常は好中球減少の最も危険な時期にのみ、短期間の**「パルス」療法**（3〜5日間）として投与されます。 * **コスト：** 治療費が非常に高額であるため、一般的な獣医療での使用は制限されることが多いです。
作用機序: Filgrastim acts as a hematopoietic growth factor. * It binds specifically to **G-CSF receptors** located on the surface of myeloid progenitor cells in the bone marrow. * Receptor activation triggers intracellular signaling pathways (such as the **JAK/STAT pathway**) → stimulates the proliferation, differentiation, and activation of progenitor cells exclusively within the **neutrophil-granulocyte lineage**. * **Clinical Pearl:** In addition to increasing the absolute number of circulating mature neutrophils, filgrastim also enhances the functional capacity of these cells, including their phagocytic and bactericidal activities, thereby improving the patient's ability to fight off bacterial infections during periods of severe immunosuppression.
動物種別の用量
- Adjunctive therapy of neutropenia (secondary to drug induced aplastic pancytopenia) · 5 micrograms/kg SC daily · SC · daily · Pulse therapy of no more than 5 days · To avoid autoantibody formation, pulse therapy is recommended.
- Neutropenia · 1-5 micrograms/kg SC daily · SC · daily · Pulse therapy of no more than 5 days · To avoid autoantibody formation, pulse therapy is recommended.
- Neutropenia · 100,000-500,000 IU (1-5 micrograms)/kg · SC · q24h · 3-5 days · Neutrophil counts typically rise within 24 hours.
- Neutropenia secondary to drug toxicity, infectious diseases, FeLV associated cyclic neutropenia or idiopathic causes · 5 micrograms/kg SC twice daily · SC · twice daily · Pulse therapy of no more than 5 days · Cost and/or development of antibodies usually limit usefulness to a few weeks, but often it is effective for acute or lifethreatening neutropenia.
- Neutropenia · 1-5 micrograms/kg SC daily · SC · daily · Pulse therapy of no more than 5 days · To avoid autoantibody formation, pulse therapy is recommended.
- Adjunctive therapy of neutropenia · 5 micrograms/kg SC daily until neutrophil count exceeds 3,000/mcl for 2 days · SC · daily · Until neutrophil count exceeds 3,000/mcl for 2 days (ideally ≤ 5 days) · To avoid autoantibody formation, pulse therapy is recommended.
- Neutropenia · 100,000-500,000 IU (1-5 micrograms)/kg · SC · q24h · 3-5 days · Neutrophil counts typically rise within 24 hours.
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
- Hypersensitivity to filgrastim
- Patients that have previously developed antibodies to filgrastim with resultant neutropenia
有害事象
- Severe neutropenia (due to autoantibody formation against G-CSF)
- Myelofibrosis (theoretical/reported concern)
- Medullary histiocytosis (theoretical/reported concern)
- Injection site irritation
- Bone pain
- Splenomegaly
- Hypotension
薬物相互作用
- Antineoplastics · Avoid using filgrastim within 24 hours of administering antineoplastic agents that target rapidly proliferating cells, as it may exacerbate toxicity to the newly stimulated myeloid cells.
- Corticosteroids · May potentiate the release of neutrophils during G-CSF therapy. · moderate
- Lithium · May potentiate the release of neutrophils during G-CSF therapy. · moderate
- Cytotoxic Chemotherapy · Concurrent administration may increase the incidence of adverse effects. The stimulatory effects of G-CSF on haemopoietic precursors render them more susceptible to the effects of chemotherapy. · major
モニタリング
- CBC with platelets, routinely (to monitor neutrophil response and detect potential antibody-induced neutropenia)
過量投与
Limited information is available regarding acute toxicity. Because of the high expense of the drug and its apparent limited acute toxic potential, clinically significant overdoses are considered unlikely. If an overdose occurs, monitor CBC closely and provide supportive care.
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。