アシトレチン
**アシトレチン (Acitretin)** は第2世代の全身性レチノイドであり、エトレチナートの活性代謝物です。 * 主に獣医皮膚科において、重度の角化異常症、皮脂腺異常、および特定の皮膚腫瘍の管理に使用されます。 * 半減期が著しく短く、組織への蓄積期間とそれに伴う長期毒性が軽減されるため、ヒト市場ではエトレチナートに取って代わりました。 * **臨床のポイント**: 犬の葉状魚鱗癬、脂腺炎、日光誘発性前癌病変などの状態に非常に有効ですが、獣医療での使用は、高コスト、催奇形性のリスク、および小型動物への正確な投与のための調剤の必要性により制限されることがよくあります。
作用機序: 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).
動物種別の用量
- 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
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
- Pregnancy (absolute contraindication)
- Cardiovascular disease
- Hypertriglyceridemia
- Known sensitivity to acitretin or other retinoids
有害事象
- 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)
薬物相互作用
- 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).
モニタリング
- 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)
過量投与
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 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。