Top 5 Things to Know About Janus Kinase Inhibitors
Sponsored by Elanco
Pruritus due to allergic dermatitis is a common presenting complaint of veterinary patients. Treatment strategies vary depending on the underlying cause, with atopic dermatitis, flea allergy dermatitis, and food allergies being the most common causes.
Antipruritic medication often plays a major role in keeping pets with allergic dermatitis comfortable, preserving quality of life, and preventing secondary infections.1 Used to treat allergic dermatitis in dogs, Janus kinase (JAK) inhibitors are an antipruritic drug class lauded for their high degree of efficacy and rapid onset.2
Explore 5 key things to know about using JAK inhibitors in clinical practice.
1. JAK Inhibitors Are Not Exclusive to Veterinary Medicine
JAK inhibitors have been used in human medicine since 2011 to treat a variety of inflammatory conditions, including rheumatoid arthritis, ulcerative colitis, and atopic dermatitis.3 In veterinary medicine, 2 JAK inhibitors are currently available for veterinary patients, with both targeting allergic and atopic dermatitis in dogs. The first commercially available JAK inhibitor, oclacitinib, was approved in 2013,4 with a second JAK inhibitor, Zenrelia™ (ilunocitinib tablets), approved in 2024.5
2. Veterinary JAK Inhibitors Work by Breaking the Itch–Scratch Cycle
JAK inhibitors are immunomodulating drugs that inhibit the JAK-STAT (signal transducer of activation) pathway, which plays a major role in Th2-mediated inflammatory responses.2 Veterinary JAK inhibitors inhibit a variety of pruritogenic, proinflammatory, and allergy-related cytokines.6,7
3. JAK Inhibitors Can Be Used for Short-Term Pruritus Control or Long-Term for Maintenance Therapy
Although some dogs with allergic dermatitis require long-term therapy with antipruritic medication, others may need treatment only during a flare or certain seasons. JAK inhibitors are rapidly absorbed and have a quick onset of action. Dogs receiving Zenrelia™ (ilunocitinib tablets) have been shown to quickly and visibly experience improvements in itch after starting the medication.9
Long-term use of JAK inhibitors in dogs has been shown to be safe and effective.8,9 One safety and efficacy study comparing oclacitinib and ilunocitinib showed a dramatic reduction in pruritus visual analog scale (PVAS) and canine atopic dermatitis extent and severity index 4 (CADESI-4) scores for patients receiving either drug.9
4. JAK Inhibitors Can Be Used Concomitantly with Allergen-Specific Immunotherapy & Other Common Medications
Many dogs with allergic disease may have a secondary infection, need to undergo allergy testing, or have a variety of other medical needs. JAK inhibitors do not interfere with the results of intradermal allergen testing, and they can be given alongside other common medications such as NSAIDs, antifungals, antibiotics, and parasiticides.2,10 Neither oclacitinib nor ilunocitinib has been evaluated with concurrent administration of cyclosporine, glucocorticoids, or other immunosuppressive agents.6,11 It should be noted that Zenrelia does have a boxed warning related to fatal vaccine-induced disease from modified live virus vaccines and inadequate immune response to any vaccine. Read the entire package insert, including the boxed warning, before using this drug.
5. Because JAK Inhibitors Are Immunomodulators, They Have the Potential to Be Immunosuppressive at Higher-Than-Label Doses or in Otherwise Immunocompromised Patients
Although JAK inhibitors are generally well tolerated, appropriate patient selection is important to mitigate the risk for immunosuppression and increased susceptibility to infections.4,6 These dose-dependent risks are highest in immunosuppressed dogs and those younger than the approved age of veterinary JAK inhibitors.6,9 Understanding of the full product label is important when prescribing JAK inhibitors.
Conclusion
JAK inhibitors such as Zenrelia™ (ilunocitinib tablets) are a quick-acting option for dogs experiencing pruritus due to allergic or atopic dermatitis and can be used for long-term control of canine atopy. Notably, Zenrelia™ (ilunocitinib tablets) is given once-daily from the start of treatment, which can help avoid potential rebound pruritus that can occur with medications requiring an initial loading dose followed by a dose reduction.6,12
It is important to consider that JAK inhibitors are immunomodulators and can be immunosuppressive at higher-than-label doses or in young or immunocompromised patients. Because dogs can have varying clinical responses to different JAK inhibitors, having multiple options available allows veterinarians to better address the needs of a broader range of canine patients suffering from allergic disease.8
INDICATIONS
Zenrelia is indicated for control of pruritus associated with allergic dermatitis and control of atopic dermatitis in dogs at least 12 months of age.
IMPORTANT SAFETY INFORMATION
Read the entire package insert before using this drug, including the Boxed Warning. For Full prescribing information, call 1 888 545 5973 or visit www.elancolabels.com/us/zenrelia.
WARNING: VACCINE-INDUCED DISEASE AND INADEQUATE IMMUNE RESPONSE TO VACCINES. Based on results of the vaccine response study, dogs receiving Zenrelia are at risk of fatal vaccine-induced disease from modified live virus vaccines and inadequate immune response to any vaccine. Discontinue Zenrelia for at least 28 days to 3 months prior to vaccination and withhold Zenrelia for at least 28 days after vaccination. Dogs should be up to date on vaccinations prior to starting Zenrelia. Do not use in dogs less than 12 months old or dogs with a serious infection. Monitor dogs for infections because Zenrelia may increase susceptibility to opportunistic infections. Neoplastic conditions (benign and malignant) were observed during clinical studies. Consider the risks and benefits of treatment in dogs with a history of recurrence of these conditions. The most common adverse reactions were vomiting, diarrhea and lethargy. Zenrelia has not been evaluated in breeding, pregnant, or lactating dogs and concurrent use with glucocorticoids, cyclosporine, or other systemic immunosuppressive agents has not been tested. For full prescribing information, see package insert.
Zenrelia, Elanco, and the diagonal bar logo are trademarks of Elanco or its affiliates. PM-US-24-2294.
