阿維A
**阿維A (Acitretin)** 是一種第二代全身性維生素A衍生物，也是依曲替酯 (etretinate) 的活性代謝物。 * 主要用於獸醫皮膚科，治療嚴重的角化異常、皮脂腺異常及某些皮膚腫瘤。 * 由於其半衰期明顯較短，減少了在組織中蓄積的時間及相關的長期毒性，因此在人類市場上取代了依曲替酯。 * **臨床要點**：雖然對犬層狀魚鱗癬、皮脂腺炎和日光性癌前病變等疾病非常有效，但其在獸醫學中的應用常受限於高昂的成本、致畸胎風險，以及小型病患需要重新配藥以達到準確劑量的問題。
作用機制: Acitretin works by interacting with intracellular receptors to modulate cellular differentiation and proliferation. * Binds to nuclear **Retinoic Acid Receptors (RARs)** and **Retinoid X Receptors (RXRs)**. * Receptor-ligand complexes bind to specific DNA sequences → **alters gene transcription**. * **Pharmacodynamic Effects**: Normalizes keratinocyte differentiation, reduces epidermal hyperproliferation, decreases sebum production, and exerts anti-inflammatory and antineoplastic effects (particularly against squamous cell carcinomas).
各物種劑量
- Actinic keratosis/solar-induced squamous cell carcinoma; or Bowen's Disease · 10 mg per cat · PO · once daily · Note: This dose is for etretinate, but as the smallest capsule is 10 mg, this dose may need to suffice as well for cats.
- Bowen's Disease · 3 mg/kg/day · PO · once daily
- Dermatologic conditions where retinoids may be useful · 0.5-1 mg/kg · PO · once daily
- Dermatologic conditions where retinoids may be useful · 0.5-2 mg/kg · PO · once daily
- Sebaceous adenitis · 0.5-1 mg/kg · PO · once daily
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
- Pregnancy (absolute contraindication)
- Cardiovascular disease
- Hypertriglyceridemia
- Known sensitivity to acitretin or other retinoids
不良反應
- Anorexia
- Vomiting
- Diarrhea
- Cracking of foot pads
- Pruritus
- Ventral abdominal erythema
- Polydipsia
- Lassitude
- Joint pain/stiffness
- Eyelid abnormalities
- Keratoconjunctivitis sicca (KCS)
- Swollen tongue
- Behavioral changes
- Weight loss (especially in cats)
藥物相互作用
- Alcohol · Acitretin can form etretinate in the presence of alcohol; etretinate is a teratogen with an extremely long terminal half-life that can persist in adipose tissue for years.
- Hepatotoxic drugs (e.g., methotrexate, ketoconazole, sulfonamides, fluconazole, macrolides) · May increase the potential for hepatotoxicity.
- Other retinoids (isotretinoin, tretinoin, vitamin A) · May cause additive toxic effects.
- Tetracyclines · May increase the potential for the occurrence of pseudotumor cerebri (cerebral edema and increased CSF pressure).
監測
- Clinical efficacy
- Liver function tests (baseline and if clinical signs appear)
- Schirmer tear tests (monthly, especially in older dogs)
- Serum triglycerides and cholesterol (recommended based on human data)
過量
Information on overdoses with this agent remains limited. One oral overdose (525 mg) in a human patient resulted only in vomiting. The oral LD50 in rats and mice is >4 grams/kg.
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。