ツラスロマイシン
**ツラスロマイシン**は、トリアミライド亜属の半合成・長作用型マクロライド系抗生物質です。主に大動物（牛および豚）の呼吸器疾患、牛の趾間腐爛、および伝染性牛角結膜炎（ピンクアイ）の治療に使用されます。 * **独自の構造**: 3つのアミン基（三塩基性）を持ち、古いマクロライド系よりもグラム陰性病原体への浸透性に優れています。 * **標的送達**: 宿主の食細胞（マクロファージや好中球）に広範に蓄積し、感染した肺組織に直接高濃度の薬物を送達します。 * **利便性**: 組織半減期が非常に長いため（牛の肺で最大8.75日）、単回投与用に製剤化されています。 > **臨床のポイント**: 主に家畜用に承認されていますが、子馬のロドコッカス・エクイ（*Rhodococcus equi*）感染症や、小型反芻動物の感受性呼吸器病原体に対して適応外使用されることがあります。
作用機序: Tulathromycin binds to the **50S ribosomal subunit** of susceptible bacteria → blocks transpeptidation and translocation processes → inhibits RNA-dependent protein synthesis. * Generally considered **bacteriostatic**, but exhibits **bactericidal** activity against key respiratory pathogens like *Mannheimia haemolytica* and *Pasteurella multocida*. * Its low affinity for bacterial efflux pumps allows it to remain and accumulate within the bacteria. * Concentrates in host phagocytic cells (macrophages) → migrates to sites of inflammation → releases active drug directly at the infection site, providing targeted therapy.
動物種別の用量
- Bovine respiratory disease (BRD), bovine foot rot, infectious bovine keratoconjunctivitis (IBK) · 2.5 mg/kg (1.1 mL/100 lb) BW · SC · single dose · Inject subcutaneously in the neck. Do not inject more than 10 mL per injection site.
- Rhodococcus equi infections in foals · 2.5 mg/kg · IM · every 5-7 days · Anecdotally used successfully in milder clinical cases.
- Swine respiratory disease (SRD) · 2.5 mg/kg (0.25 mL/22 lb) BW · IM · single dose · Inject intramuscularly in the neck. Do not inject more than 2.5 mL per injection site.
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 to tulathromycin or other macrolides
- Female dairy cattle 20 months of age or older
- Calves to be processed for veal
- Pre-ruminating calves (withdrawal period not established)
有害事象
- Transient hypersalivation
- Transient dyspnea (rare)
- Injection site reactions (swelling, pain, discoloration, trim loss at slaughter)
- Anorexia
- Restlessness and excessive vocalization (swine)
モニタリング
- Clinical efficacy (resolution of respiratory signs, lameness, or ocular lesions)
- Injection site for severe reactions
過量投与
### Cattle Single subcutaneous doses of up to 25 mg/kg caused transient indications of pain at the injection site, including head shaking and pawing at the ground. Injection site swelling, discoloration of subcutaneous tissues, and corresponding histopathologic changes were observed. ### Swine Single IM doses of up to 25 mg/kg caused transient indications of pain at the injection site, restlessness, and excessive vocalization. Brief tremors occurred in one animal receiving 7.5 mg/kg. ### Treatment No systemic treatment for single overdoses should be necessary. Localized treatment at the injection site (e.g., ice pack) to reduce swelling and pain, as well as FDA-approved analgesic medications, can be considered.
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。