クロピドグレル
**クロピドグレル**は、獣医療において危険な血栓症の予防に広く使用される強力な経口血小板凝集阻害薬（チエノピリジン系）です。 - **猫の医療**：基礎疾患として心疾患（肥大型心筋症など）を持つ猫の**猫大動脈血栓塞栓症（FATE）**の予防に頻繁に使用されます。また、血管調節作用により、塞栓イベント後の後肢の血流を改善する可能性もあります。 - **犬の医療**：**免疫介在性溶血性貧血（IMHA）**、蛋白漏出性腸症/腎症（PLE/PLN）、副腎皮質機能亢進症などの疾患に関連する血液凝固能亢進状態の管理に使用されます。 **臨床のポイント**：クロピドグレルは非常に苦いことで知られています。猫が錠剤の味を感じると、大量のよだれを流すことがあります。確実な投薬のために、空のゼラチンカプセルに薬を入れて投与することを強くお勧めします。
作用機序: Clopidogrel is a **prodrug** that requires hepatic biotransformation (via **CYP450** enzymes) to its active, highly unstable thiol metabolite. - The active metabolite → binds selectively and **irreversibly** to the **P2Y12** subtype of **ADP-receptors** on the platelet surface. - This blocks **ADP** binding → prevents activation of the **glycoprotein IIb/IIIa** complex. - Without this complex, platelet-fibrinogen binding cannot occur, effectively halting both primary and secondary platelet aggregation. - It also inhibits the release of other pro-aggregation compounds (serotonin, calcium, thromobospondin). Because the binding is irreversible, the platelet is inhibited for its entire lifespan (approximately 7-10 days). Normal coagulation only returns as new platelets are synthesized.
動物種別の用量
- As an anti-platelet agent · 1-3 mg/kg PO once daily; if used with aspirin give lower doses (0.5-1 mg/kg PO once daily) · PO · once daily
- Thromboprophylaxis · 1.1-4 mg/kg · PO · q24h · A single loading dose of 4-10 mg/kg p.o. may help achieve therapeutic concentrations more rapidly.
- To prevent thrombus formation · 18.75 mg (practically, 1/4 of a 75 mg tablet) PO once daily · PO · once daily
- To prevent thrombus formation (combination therapy) · 7 mg (total dose) PO once daily in combination with aspirin 40-81 mg (total dose) every 3 days. · PO · once daily · Clinical trials are needed to determine appropriate dosage and indications.
- To prevent thrombus formation · 1-3 mg/kg PO once daily; if used with aspirin give lower doses (0.5-1 mg/kg PO once daily) · PO · once daily
- Thromboprophylaxis · 18.75 mg/cat · PO · q24h · A single loading dose of 4-10 mg/kg p.o. may help achieve therapeutic concentrations more rapidly. Administer in a gelatin capsule to improve compliance due to bitter taste.
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
- Active pathologic bleeding
- Known hypersensitivity to the drug
有害事象
- Vomiting
- Anorexia
- Bleeding/hemorrhage
- Diarrhea
- Rashes
- Thrombotic thrombocytopenic purpura (TTP) - rare in humans
薬物相互作用
- Aspirin · Increased risk for bleeding; however, many patients take both medications intentionally for dual antiplatelet therapy. · moderate
- Heparin / Low Molecular Weight Heparins (LMWH) · Clopidogrel appears safe to use concurrently with heparin.
- NSAIDs · Increased risk for bleeding; clopidogrel may interfere with NSAID metabolism.
- Phenytoin · Clopidogrel may interfere with phenytoin metabolism.
- Proton Pump Inhibitors (e.g., omeprazole) · May decrease the efficacy of clopidogrel by inhibiting CYP2C19, the enzyme needed to convert clopidogrel to its active metabolite.
- Torsemide · Clopidogrel may interfere with torsemide metabolism.
- Warfarin · Increased risk for bleeding; clopidogrel may interfere with warfarin metabolism.
- Anticoagulants · High risk of bleeding complications · major
モニタリング
- Clinical efficacy (prevention of thromboembolic events)
- Adverse effects (vomiting, anorexia)
- Signs of bleeding (petechiae, ecchymosis, melena, epistaxis)
過量投与
Limited information is available. Reported lethal oral doses for mice and rats were 1500 mg/kg and 2000 mg/kg, respectively. **Clinical Signs**: Acute toxic signs may include bleeding or vomiting. **Treatment**: Platelet transfusions have been suggested if rapid reversal is required.
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。