Oclacitinib Maleate(PF-03394197)

APOQUEL (oclacitinib maleate) was the first selective Janus kinase (JAK) inhibitor to be developed for dogs. It was recently approved for the control of pruritus associated with allergic dermatitis and control of atopic dermatitis in dogs at least 12 months of age. In recent years, there has been a significant evolution in understanding regarding the pathophysiology of allergic and atopic diseases. The molecular mechanisms involved in stimulating the itch response have been elaborated (Marsella et al., 2012), and it is now understood that cytokines play a key role in initiating the neuronal itch stimulation which triggers pruritic behavior (scratching, rubbing, chewing, etc.) in dogs. This leads to the establishment of a vicious cycle of itch that exacerbates skin lesions and amplifies defects in the skin barrier function in clinically affected dogs. This progress provided the opportunity to develop new treatments (Marsella et al., 2012). Specifically, Janus kinases play a central role in cytokine signaling and are involved in signal transduction of many pro-inflammatory, pro-allergic, and pruritogenic cytokines including IL-2, IL-4, IL-6, IL-13, and IL-31 that are implicated in allergic conditions (Ong & Leung, 2006; Carmi-Levy et al., 2011).

Oclacitinib is labeled to treat atopic dermatitis and itchiness (pruritus) caused by allergies in dogs, though it has also been used to reduce the itchiness and dermatitis caused by flea infestations. It is considered to be highly effective in dogs, and has been established as safe for at least short-term use. Its efficacy equals that of prednisolone at first, though oclacitinib has been found to be more effective in the short term in terms of itchiness and dermatitis, long term safety is unknown. It has been found to have a faster onset and cause less gastrointestinal issues than cyclosporine. While safe in the short term, oclacitinib's long-term safety is unknown. While some say it is best only for acute flares of itchiness, others claim that it is also useful in chronic atopic dermatitis.