丙美卡因 / 普羅帕卡因
丙美卡因（又稱普羅帕卡因）是一種快速起效的局部麻醉劑，主要用於眼球表面（角膜和結膜囊）、外耳道和鼻腔。它能迅速起效（1分鐘內），並根據物種不同提供25-55分鐘的麻醉效果。 > **臨床警告：** 所有局部麻醉劑對角膜上皮均有毒性。反覆使用會延遲潰瘍癒合，並可能導致嚴重的角膜溶解。**絕對不能作為居家止痛藥物開立給畜主。** **臨床提示：** 連續點藥可增加麻醉的持續時間和深度。由於局部麻醉劑會阻斷反射性淚液分泌，因此不應在進行淚液測試（Schirmer tear test）之前使用。
作用機制: Local anaesthetic action is dependent on the **reversible blockade of voltage-gated sodium channels** → prevents the influx of sodium ions → inhibits the propagation of an action potential along the nerve fibre. Sensory nerve fibres are blocked before motor nerve fibres, allowing a selective sensory blockade at low doses.
各物種劑量
- Ocular surface anaesthesia · 1-2 drops/eye · topical · PRN · Single application (or serial for depth) · Maximal effect at 15 min, duration 45-55 min.
- Aural/nasal anaesthesia · 5-10 drops/ear or nose · topical · q5-10min · Maximum 3 doses if used intranasally
- Ocular surface anaesthesia · 1-2 drops/eye · topical · PRN · Single application · Maximal effect at 15 min, duration 25 min.
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
- Therapeutic use (e.g., home pain management)
- Application prior to a Schirmer tear test
不良反應
- Conjunctival hyperaemia (common)
- Local irritation / chemosis (occasional)
- Corneal epithelial toxicity
- Delayed corneal ulcer healing
監測
- Corneal integrity (fluorescein staining if damage is suspected)
- Resolution of anaesthesia (protect the eye from trauma while numb)
過量
Overdosage via repeated topical application leads to **severe corneal toxicity**, epithelial sloughing, delayed healing of ulcers, and potentially corneal melting. Systemic toxicity is rare with standard ophthalmic use but could theoretically cause CNS excitation followed by depression and cardiovascular collapse if massive amounts are absorbed through mucous membranes.
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。