“H4” Antihistamine

“H4” Antihistamine

The Journal of Allergy and Clinical Immunology recently published research on an experimental H4-antihistamine investigated at the University of Hanover.  The research is part of a global effort to find more effective therapies for atopic dermatitis (eczema).  The prevalence of atopic dermatitis has doubled in the past 30 years with occurrence in between 15% to 30% of children and 2% to 10% of adults.  It is characterized by chronic relapsing itching of the skin which develops bumps and scaling, and can weep fluid in its severe form.  The itch is very problematic often disrupting life activities and sleep. 

Current therapies include improving skin barrier function through moisturizers and wet wraps, dilute bleach baths to reduce skin bacteria overgrowth, topical and systemic steroids, topical calcineurin inhibitors, topical phosphodiesterase inhibitor, phototherapy, and for very severe cases injectable monoclonal antibodies.  To date, the available antihistamines have proven to be of very modest value.  The traditional antihistamines block either H1: Benadryl, Claritin, Allegra, Zyrtec, Xyzal or H2: Zantac, Pepcid, Tagamet, and Axid.  These are of modest benefit because the skin cells have only a small number of H1 and H2 receptors.  But as it turns out, there are many H4 receptors on skin cells, hence research to find an effective and safe H4 antihistamine. 

The drug ZPL-3893787 just might fit the bill.  Recently developed by German scientists it proved to be extremely effective in a large-scale clinical trial.  It led to a very remarkable lessening of itch but also to healing of the skin.  The H4 receptors in the skin mediate both pruritis and inflammation.  By blocking the H4 receptor “ZPL” seems to both stop the itch and heal the skin.  If further studies give similar results it will prove to be a “God-send” for atopic dermatitis patients.  


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