Two JAK inhibitors are currently approved for veterinary dermatology in dogs: oclacitinib (Apoquel; Zoetis) and ilunocitinib (Zenrelia; Elanco Animal Health). Both are approved for dogs one year of age or older, and both target the JAK–signal transducer and activator of transcription (JAK–STAT) pathway to suppress pruritogenic and pro-inflammatory cytokines including IL-2, IL-4, IL-6, IL-13, and IL-31.BMC Veterinary…+2
Oclacitinib is a selective JAK1 inhibitor approved in the United States in 2013 for control of pruritus associated with allergic dermatitis and control of atopic dermatitis (AD) in dogs ≥12 months of age.Journal of the…+1 In isolated enzyme assays, oclacitinib inhibited JAK1, JAK2, JAK3, and tyrosine kinase 2 (TYK2) by 50% at concentrations of 10, 18, 99, and 84 nM, respectively, demonstrating 1.8-fold selectivity for JAK1 over JAK2 and 9.9-fold selectivity for JAK1 over JAK3.Journal of the… In cell-based in vitro studies, oclacitinib did not have major effects on granulocyte-macrophage colony-stimulating factor, erythropoietin, IL-12, or IL-23 at tested concentrations, reflecting its preferential activity against JAK1- and JAK3-dependent cytokines over JAK2-dependent pathways important in hematopoiesis.Journal of the… The approved dosage is 0.4–0.6 mg/kg PO twice daily for up to 14 days, then once daily thereafter.Journal of the… Up to one-third of dogs do not achieve satisfactory control of clinical signs on oclacitinib.Veterinary Derm…+1
Ilunocitinib is a non-selective JAK inhibitor with high potency for JAK1, JAK2, and TYK2 inhibition, approved for allergic and atopic dermatitis in dogs ≥1 year of age.BMC Veterinary…+1 Unlike oclacitinib, ilunocitinib is dosed at 0.6–0.8 mg/kg PO once daily throughout the treatment course, without a frequency reduction at day 14.Veterinary Derm…+1 The fixed once-daily schedule avoids the pruritus rebound seen with oclacitinib when dosing is stepped down from twice to once daily at day 14.Veterinary Derm… At day 28, 83% of ilunocitinib-treated dogs achieved treatment success (defined as ≥50% reduction from baseline pruritus Visual Analog Scale or Canine Atopic Dermatitis Extent and Severity Index, 4th iteration score) compared to 31% of placebo-treated dogs.Veterinary Derm… Clinical remission of pruritus (pruritus Visual Analog Scale score <2) was achieved by two-thirds of dogs after 4 months of treatment.Veterinary Derm… In direct comparison with oclacitinib, mean pruritus and skin lesion scores were significantly lower for ilunocitinib from day 28 through day 112, with more ilunocitinib-treated dogs achieving clinical remission of pruritus during that period.Veterinary Derm…
Safety profiles are similar between the two drugs. Both demonstrated comparable safety throughout the 112-day comparative trial.Veterinary Derm… The 112-day ilunocitinib treatment course was well tolerated in the placebo-controlled trial.Veterinary Derm…
| Drug | Dose & Route | JAK Selectivity | Efficacy Highlight | Key Caveat |
|---|---|---|---|---|
| Oclacitinib | 0.4–0.6 mg/kg PO q12h ×14 days, then q24h | JAK1 > JAK2 (1.8×), JAK1 > JAK3 (9.9×) | Established 10+ year safety record | Up to one-third of dogs non-responsive; pruritus rebound at dose step-down |
| Ilunocitinib | 0.6–0.8 mg/kg PO q24h throughout | JAK1, JAK2, TYK2 (non-selective) | 83% treatment success at D28; two-thirds in clinical remission at 4 months | Approved dogs ≥1 year; newer agent with shorter post-market history |
Would you like a comparison of how these two drugs perform specifically in dogs that have previously failed oclacitinib?