倍他米松
**倍他米松**是一種強效、長效的糖皮質激素，在獸醫學中主要用於其顯著的抗炎和免疫抑制作用。在眼科應用中，它曾作為獸醫批准的抗菌-類固醇複方製劑（Gentocin Durafilm®）提供。雖然目前已停產，但調劑藥劑師仍可根據特定臨床需求提供慶大黴素和倍他米松的複方製劑。
作用機制: Betamethasone diffuses across cell membranes and binds to specific cytosolic **glucocorticoid receptors**. The receptor-ligand complex translocates to the nucleus, where it alters gene expression (transactivation and transrepression). → **Inhibits phospholipase A2** (via lipocortin induction), blocking the release of arachidonic acid. → **Decreases production of inflammatory mediators** (prostaglandins, leukotrienes, cytokines). → **Suppresses immune system response** by reducing leukocyte migration and capillary permeability.
給藥途徑
禁忌症
- Suspected corneal abrasion
- Corneal ulceration
- Feline herpes keratitis (FHV-1)
不良反應
- Delayed corneal healing
- Increased intraocular pressure (IOP)
- Potentiation of ocular infections
- Systemic absorption leading to adrenal suppression (rare with topical use but possible in small patients)
藥物相互作用
- NSAIDs · Increased risk of GI ulceration · major
- Insulin · Glucocorticoids antagonize the effect of insulin · major
- Phenobarbital · May accelerate the metabolism of corticosteroids · moderate
- Itraconazole · May decrease the metabolism of corticosteroids · moderate
- Acetazolamide · Increased risk of hypokalaemia · moderate
- Amphotericin · Increased risk of hypokalaemia · moderate
- Furosemide · Increased risk of hypokalaemia · moderate
- Thiazide diuretics · Increased risk of hypokalaemia · moderate
監測
- Fluorescein staining (to ensure intact cornea prior to and during use)
- Intraocular pressure (IOP)
- Resolution of clinical signs of inflammation
過量
Overdose via topical ophthalmic administration is unlikely to cause acute life-threatening signs, but chronic overuse can lead to iatrogenic hyperadrenocorticism (Cushing's syndrome) and local ocular complications (glaucoma, corneal degeneration).
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。