Oclacitinib
**Oclacitinib** is a targeted immunomodulatory and antipruritic medication used primarily in veterinary medicine to manage pruritus (itching) associated with allergic dermatitis and to control atopic dermatitis in dogs. > **Clinical Warning:** Oclacitinib modulates the immune system and may increase susceptibility to infections (e.g., demodicosis, pyoderma) or exacerbate pre-existing neoplastic conditions. It is contraindicated in dogs under 12 months of age due to an increased risk of severe infections. **Clinical Pearl:** Oclacitinib provides rapid relief from itching, often working as quickly as corticosteroids (within 4-24 hours), but without the polyuria/polydipsia and long-term metabolic side effects typically associated with glucocorticoids. While the provided monograph does not specify dosing, standard veterinary practice typically initiates therapy at 0.4-0.6 mg/kg twice daily for up to 14 days, followed by once-daily maintenance.
Mecanismo: 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.
Vías de administración
Contraindicaciones
- 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
Efectos adversos
- 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)
Interacciones farmacológicas
- 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
Monitoreo
- 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
Sobredosis
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.
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