マムシ亜科多価抗毒素
マムシ亜科多価抗毒素は、北米、中米、南米のマムシ亜科（ガラガラヘビ、アメリカマムシ、ヌママムシ、テルシオペロなど）の咬傷治療に適応される、救命のための重要な**解毒剤**です。 * **剤形**: **ウマ由来**製品（完全なIgG抗体）および**ヒツジ由来**製品（Fabフラグメント、例：CroFab®）があります。 * **リスク**: 動物用ウマ由来製品の最大50%にはウマアルブミンやその他のタンパク質が含まれており、過敏症（アナフィラキシー）の重大なリスクを伴います。 * **臨床のポイント**: ヒツジ由来Fab製品（CroFab）は人体用ですが、獣医療でも適応外使用されることがよくあります。Fabフラグメントは完全なIgGウマ由来製品に比べてアナフィラキシーのリスクが一般的に低いですが、半減期が短いため、毒性の再発を防ぐために反復投与が必要になる場合があります。 * 治療には積極的な支持療法が必要であり、非常に高額になることがあります。
作用機序: Antivenins provide **passive immunity** to the patient. * They contain concentrated serum globulins (or Fab fragments) obtained from animals (horses or sheep) hyperimmunized with pit viper venom. * **Mechanism**: The immunoglobulins directly bind to and neutralize the complex toxic proteins and enzymes present in the venom. * **Effect** → Rapidly reverses venom-related systemic signs and coagulation abnormalities. * *Note*: Venom-induced thrombocytopenia, particularly from Timber Rattlesnakes, may be resistant to antivenin treatment.
動物種別の用量
- Pit viper envenomation · 1-2 vials of antivenin. Initially, give one vial, by diluting to 100-250 mL of crystalloid fluids and initially administer by slow IV · IV · prn · Adjust infusion volume in smaller patients to prevent fluid overload.
- Systemic effects of envenomation · 1-2 vials slowly IV diluted in 250-500 mL saline or lactated Ringer's · IV · prn · Use only if necessary to treat systemic effects. Administer antihistamines; corticosteroids are contraindicated.
- Pit viper envenomation · 1-2 vials of antivenin. Initially, give one vial, by diluting to 100-250 mL of crystalloid fluids and initially administer by slow IV · IV · prn · Adjust infusion volume in smaller patients to prevent fluid overload. Intravascular bites or bites to torso/tongue require prompt, aggressive administration.
- Pit viper envenomation · 1-5 rehydrated vials (10-50 mL) IV depending on severity of symptoms, duration of time after the bite, snake size, patient size. Additional doses may be given every 2 hours as required. If unable to give IV, may administer IM as close to bite as practical. · IV/IM · q2h as required · The smaller the victim, the larger the dose (venom amount/kg is higher).
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
- Known severe hypersensitivity to equine or ovine proteins (relative contraindication in life-threatening envenomation)
有害事象
- Anaphylaxis (Type I hypersensitivity)
- Anaphylactoid reactions
- Serum sickness (Type III hypersensitivity, delayed)
- Nausea
- Pruritus
- Hyperemia of the inner pinna
薬物相互作用
- Analgesics/Sedatives · May mask the clinical signs associated with the venom; use with caution initially.
- Antihistamines · Theoretical risk of potentiating venom, though diphenhydramine is routinely and safely used by clinicians for pre-treatment.
- Beta-blockers · May mask the early signs associated with anaphylaxis.
- Corticosteroids · Generally out of favor for treating snakebite envenomation, but may be useful to treat secondary anaphylaxis. Contraindicated in horses per some references.
- Heparin · Reportedly not effective in treating the thrombin-like enzymes found in rattlesnake venom.
モニタリング
- Signs associated with an allergic response (anaphylaxis, anaphylactoid-reactions, serum sickness)
- CBC with platelets
- Coagulation parameters
- Biochemical profile
- Hydration status
- ECG
過量投与
Specific overdose information is not provided, but fluid overload is a significant risk in smaller patients receiving large volumes of crystalloid fluids used to dilute the antivenin.
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。