達胏素
達胏素鈉（Dalteparin sodium）是一種**低分子量胏素 (LMWH)**，主要用於預防和治療血栓栓塞性疾病。 * **機轉優勢**：與未分畋胏素 (UFH) 相比，LMWH（如達胏素）具有更可預測的藥物動力學特性，且優先針對凝血因子 Xa 而非凝血酶，從而降低自發性出血的風險。 * **獸醫臨床挑戰**：雖然在人類中每日一次或兩次給藥非常有效，但狗和貓（尤其是貓）排除達胏素的速度非常快。這需要頻繁的皮下注射（貓最多每 4-6 小時一次），使得長期門診管理變得不切實際且昂貴。 * **臨床應用**：常用於重症監護環境中，針對血栓高風險患者（例如：免疫介導性溶血性貧血、蛋白流失性腎病、貓主動脈血栓栓塞或馬絞痛）。
作用機制: Dalteparin exerts its anticoagulant effect by binding to and accelerating **antithrombin III (ATIII)**. * **Conformational Change**: Binding induces a conformational change in ATIII, significantly accelerating its ability to inactivate coagulation factors. * **Factor Xa Selectivity**: Because dalteparin consists of shorter polysaccharide chains (average molecular weight ~5000 daltons) compared to unfractionated heparin, it lacks the chain length required to simultaneously bridge ATIII and thrombin (Factor IIa). Therefore, it preferentially inhibits **Factor Xa**. * **Pathway**: Dalteparin + ATIII → **Potent inhibition of Factor Xa** → Decreased conversion of prothrombin to thrombin → Prevention of fibrin clot formation. *Clinical Pearl*: Because it minimally impacts thrombin, routine clotting times like TT or aPTT are usually unaffected and are poor monitoring tools for this drug.
各物種劑量
- Thromboembolic disease prophylaxis/treatment · 150 Units/kg · SC · q4h · Required to maintain a therapeutic target of anti-XA activity of 0.5-1 IU/mL.
- Thromboembolic disease prophylaxis/treatment · 180 Units/kg · SC · q4-6h · Current clinical dose recommendation.
- Prophylaxis of coagulation disorders in colic patients · 50 Units/kg · SC · q24h · Once daily dosing.
- Thromboembolic disease prophylaxis/treatment · 150 Units/kg · SC · q8h · Initial dose 150 Units/kg SC q8h.
- Thromboembolic disease prophylaxis/treatment · 150 Units/kg · SC · TID or BID · 150 Units/kg SC three times daily; twice daily dosing may be effective. Studies are ongoing.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
給藥途徑
禁忌症
- Hypersensitivity to dalteparin, heparin, or pork products
- Active major bleeding
- Heparin-induced thrombocytopenia
- Thrombocytopenia associated with positive in vitro tests for anti-platelet antibodies in the presence of dalteparin
- Intramuscular (IM) or Intravenous (IV) administration
不良反應
- Hemorrhage (unlikely but possible)
- Injection site hematomas or pain
- Allergic reactions
- Neurologic sequelae secondary to epidural or spinal hematomas
藥物相互作用
- Warfarin · Increased risk for hemorrhage
- Aspirin · Increased risk for hemorrhage
- Clopidogrel · Increased risk for hemorrhage
- Thrombolytic agents · Increased risk for hemorrhage
監測
- Baseline and ongoing CBC (with platelet count)
- Urinalysis
- Stool occult blood test
- Factor Xa activity (Note: To measure peak anti-Xa activity in cats, sample at 2 hours post-dose)
過量
Overdosage may lead to hemorrhagic complications. If treatment is necessary, **protamine sulfate** via slow IV may be administered. * **Dose ratio**: 1 mg of protamine sulfate can inhibit the effects of 100 units of administered anti-Xa dalteparin. * **Caution**: Avoid overdoses of protamine, as it has its own anticoagulant properties and can cause severe hypotension or anaphylactoid reactions.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。