曲吡那敏
曲吡那敏（Tripelennamine）是一種**第一代乙二胺類抗組織胺藥物**，主要應用於大型動物獸醫學中。它被用來減輕由組織胺介導的過敏反應和過敏性休克。 有趣的是，它也常被標示外使用於「倒地牛症候群（Downer cow syndrome）」作為**中樞神經系統（CNS）刺激劑**（緩慢靜脈注射）。由於它是第一代抗組織胺，能輕易穿透血腦屏障，可能會引起從鎮靜到矛盾性興奮（特別是在馬匹）等顯著的中樞神經作用。 *臨床要點*：雖然對於急性過敏反應非常有效，但由於有更新、較不易引起嗜睡的抗組織胺藥物問世，加上許多口服曲吡那敏製劑已停產，其在小動物醫學中的使用已大幅減少。
作用機制: Tripelennamine acts as a **competitive antagonist at the H1-receptor**. * **Histamine Release** → Histamine binds to H1 receptors on smooth muscle, endothelium, and the CNS. * **Tripelennamine** → Competes for these receptor sites → Prevents histamine-induced bronchoconstriction, vasodilation, and increased capillary permeability. *Note*: Antihistamines do *not* inactivate histamine or prevent its degranulation/release from mast cells; they only block its downstream effects. Compared to other antihistamines, tripelennamine has **moderate sedative activity** and **minimal anticholinergic activity**.
各物種劑量
- General antihistamine · 1 mg/kg PO q12h · PO · q12h · Oral dosage forms may no longer be obtainable
- General antihistamine · 1 mg/kg IM · IM
- General antihistamine · 1.1 mg/kg (2.5 mL per 100 lbs body weight) IV (for more immediate effect) or IM q6-12h as needed · IV/IM · q6-12h · as needed
- Downer Cow Syndrome (Adjunctive treatment) · 0.5 mg/kg slow IV in conjunction with parenteral mineral treatment · IV · Used as a CNS stimulant
- General antihistamine · 1 mg/kg IV or IM · IV/IM
- General antihistamine · 1.1 mg/kg (2.5 mL per 100 lbs body weight) IM q6-12h as needed · IM · q6-12h · as needed · Do NOT give IV. ARCI UCGFS Class 3 Drug.
- General antihistamine · 1 mg/kg IM · IM · Do NOT give IV. ARCI UCGFS Class 3 Drug.
- General antihistamine · 1 mg/kg IV or IM · IV/IM
- General antihistamine · 1 mg/kg PO q12h · PO · q12h · Oral dosage forms may no longer be obtainable
給藥途徑
禁忌症
- Intravenous (IV) administration in horses is strictly contraindicated due to severe CNS stimulation
不良反應
- CNS stimulation (hyperexcitability, nervousness, muscle tremors) - especially in horses given IV
- CNS depression / Sedation
- Ataxia / Incoordination
- Gastrointestinal disturbances
藥物相互作用
- CNS Depressants (e.g., barbiturates, opioids) · Increased sedation and CNS depression
- Heparin · May partially counteract the anticoagulation effects
- Warfarin · May partially counteract the anticoagulation effects
監測
- Clinical efficacy (resolution of allergic signs)
- Adverse effects (CNS stimulation, sedation, ataxia)
過量
Overdosage of tripelennamine can cause **CNS excitation, seizures, and ataxia**. * **Treatment**: Treat symptomatically and supportively if clinical signs are severe. * **Seizure Management**: Phenytoin (IV) is recommended in the treatment of seizures caused by antihistamine overdose in humans. **Barbiturates and diazepam are generally avoided** as they may exacerbate post-excitatory CNS depression.
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