FDA Approves Zenrelia for Itch Control in Dogs with Allergies

The U.S. Food and Drug Administration (FDA) has approved Zenrelia (ilunocitinib tablets), a new medication designed to control pruritus (itching) linked to allergic dermatitis, as well as to manage atopic dermatitis caused by environmental allergens in dogs aged one year and older. This treatment offers dog owners a new option for addressing skin-related allergy issues.

Mechanism of Action and Administration

Zenrelia is an immunosuppressant that works as a non-selective Janus kinase (JAK) inhibitor. It is administered orally, once daily, either with or without food. According to the FDA, Zenrelia is the second JAK inhibitor approved for this particular indication in dogs.

Safety Warnings and Risks

While Zenrelia has been deemed safe and effective when used as directed, it carries a critical boxed warning. Dogs should not be vaccinated within 28 days before or after receiving Zenrelia due to the risk of vaccine-induced diseases and reduced immune responses to vaccines. This concern stems from findings in a vaccine response study where treated dogs experienced serious complications.

In the study, some dogs suffered from fatal vaccine-induced adenoviral hepatitis (liver inflammation), pancreatitis, and infectious enteritis (intestinal inflammation). Furthermore, Zenrelia's immunosuppressive action prevented adequate immune responses to critical vaccines like rabies and canine distemper in several treated dogs. Specifically, four out of six treated dogs failed to respond properly to the rabies vaccine, and one dog failed to respond to the distemper vaccine.

Guidelines for Vaccination and Zenrelia Use

Given the public health risks, particularly concerning the rabies vaccine, the FDA recommends withholding Zenrelia for 28 days to three months before vaccinating a dog, and also for at least 28 days afterward. Additionally, ensuring that dogs are up-to-date on their vaccinations before starting Zenrelia treatment is essential for avoiding potential health complications.

Prescription and Availability

Zenrelia is available exclusively through licensed veterinarians, who can assess whether this treatment is appropriate and monitor for potential side effects such as infections. The drug is offered in four strengths: 4.8 mg, 6.4 mg, 8.5 mg, and 15 mg tablets, with packaging options including blister packs of 10 and 30 tablets, as well as 90-count bottles.

The product is sponsored by Elanco, a company based in Greenfield, Indiana.

Highlights:

• FDA Approval: Zenrelia has been approved to control itching and treat allergic dermatitis in dogs one year and older.
• Mechanism: The active ingredient, ilunocitinib, is a non-selective JAK inhibitor that suppresses the immune system to alleviate symptoms.
• Safety Warning: Dogs should not be vaccinated within 28 days before or after treatment due to risks of vaccine-induced diseases and inadequate immune responses.
• Vaccine Concerns: In studies, treated dogs experienced fatal liver inflammation, pancreatitis, and poor responses to rabies and distemper vaccines.
• Prescription Only: Zenrelia is available through licensed veterinarians and comes in four tablet strengths.