オクラシチニブ
**オクラシチニブ**は、主に犬のアレルギー性皮膚炎に関連するそう痒（かゆみ）の管理やアトピー性皮膚炎のコントロールに使用される、分子標的免疫調節薬および止痒薬です。 > **臨床上の警告：** オクラシチニブは免疫系を調節するため、感染症（毛包虫症、膿皮症など）への感受性を高めたり、既存の腫瘍性疾患を悪化させる可能性があります。重篤な感染症のリスクが高まるため、12ヶ月齢未満の犬への使用は禁忌です。 **臨床のポイント：** オクラシチニブはかゆみを迅速に緩和し、多くの場合コルチコステロイドと同等の速さ（4〜24時間以内）で効果を発揮しますが、糖質コルチコイドに特有の多飲多尿や長期的な代謝性副作用を伴いません。
作用機序: Oclacitinib is a targeted enzyme inhibitor that specifically **inhibits Janus-kinases (JAK)**, with a pronounced selectivity for **JAK1** and, to a lesser extent, JAK3. By blocking these enzymes, oclacitinib prevents the signal transduction of a variety of cytokines dependent on JAK1/JAK3 pathways. Most notably, it inhibits **Interleukin-31 (IL-31)**, a key pruritogenic (itch-inducing) cytokine in dogs. Pathway: Cytokine binds to receptor → **JAK1/JAK3** activation is blocked → STAT proteins are not phosphorylated → Pro-inflammatory and pruritogenic gene transcription is halted.
投与経路
禁忌
- Dogs less than 12 months of age
- Dogs weighing less than 3 kg
- Dogs with severe systemic infections
- Breeding, pregnant, or lactating dogs
- Dogs with evidence of immune suppression (e.g., hyperadrenocorticism)
- Dogs with a history of progressive malignant neoplasia
有害事象
- Gastrointestinal upset (vomiting, diarrhea, anorexia)
- Lethargy
- Increased susceptibility to infections (e.g., pyoderma, otitis, demodicosis, pneumonia)
- Transient decreases in leukocytes and serum globulins
- Potential exacerbation of neoplastic conditions
- Histiocytomas or papillomas (benign skin masses)
薬物相互作用
- Corticosteroids · Increased risk of immunosuppression and secondary infections. · major
- Cyclosporine · Increased risk of profound immunosuppression. · major
- Modified live vaccines · Potential for decreased vaccine efficacy or vaccine-induced illness due to immunomodulation. · moderate
モニタリング
- Baseline CBC, serum biochemistry, and urinalysis
- Periodic bloodwork (e.g., every 6-12 months) for dogs on long-term therapy
- Monitor for new or worsening skin, ear, or systemic infections
- Monitor for the development of cutaneous or systemic neoplastic lesions
過量投与
Overdoses up to 3-5 times the therapeutic dose are generally well tolerated but may increase the frequency and severity of expected side effects, particularly **gastrointestinal distress** (vomiting, diarrhea), **lethargy**, and localized **alopecia** or skin thickening. Chronic massive overdose increases the risk of severe immunosuppression and secondary infections. Treatment is supportive and symptomatic, as there is no specific antidote.
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。