said Alice He, MD, at the Center for Dermatology Research, Wake Forest University, Winston-Salem, N.C., and her associates.
Results of double-blind, randomized trials have found that oral antihistamines do not effectively treat itch associated with atopic dermatitis (AD), and American Academy of Dermatology guidelines state that intermittent short-term use of sedating antihistamines may help insomnia secondary to itch, but should not be substituted for topical treatments in atopic dermatitis management (J Am Acad Dermatol. 2014;71[2]:327-49), the investigators said. Nonetheless, physicians continue to prescribe antihistamines to AD patients.
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Sedating antihistamines accounted for the majority of antihistamines prescribed by pediatricians (58%) and dermatologists (70%) for AD. Nonsedating antihistamines accounted for the majority of the antihistamines prescribed by family physicians (84%), internists (100%), and other specialists (55%), the investigators said.
(The sedating antihistamines prescribed included hydroxyzine, diphenhydramine, chlorpheniramine, brompheniramine, and cyproheptadine; nonsedating antihistamines include cetirizine, desloratadine, levocetirizine, loratadine, and fexofenadine.)
Although the AAD guidelines allow intermittent, short-term use of sedating antihistamines to treat AD-associated itch, these medications may be harmful to sleep in terms of reduced sleep quality and decreased REM sleep. Also, studies have shown that their effects can persist into the daytime and have the potential to impair cognitive function, including learning and memory.
“Physicians should consider the potential risks when prescribing sedating antihistamines as adjunctive treatment for atopic dermatitis,” Dr. He and her associates warned in the article in the Journal of the American Academy of Dermatology.
The researchers took a look at the top ten comorbidities reported among visits for AD, because nonsedating antihistamines might have been prescribed for a different diagnosis. There were three conditions for which antihistamines may be indicated: allergic rhinitis (13%), dermatitis attributable to food (8.5%), and conjunctivitis (3%). This “validates antihistamine prescriptions for a maximum of only 24.5% of patients who received antihistamines, indicating that a large proportion of antihistamine prescriptions were prescribed specifically for AD,” they said.
The authors said that, “while histamine does not play a role in AD via H1R [histamine-1 receptor], it may still be relevant in AD pathogenesis through actions on its most recently described receptor, histamine-4 receptor (H4R).”
“The advent of new targeted systemic therapies, such as T-helper 2 cytokine antagonists and H4R antagonists,” may one day help fill “the unmet need for effective treatments for atopic dermatitis,” Dr. He and her associates concluded.
The Center for Dermatology Research is supported by an unrestricted educational grant from Galderma Laboratories. Dr. He listed no other relevant financial disclosures. Her coauthors disclosed research, speaking, and/or consulting support from a variety of pharmaceutical companies; one author is an employee of Abbvie.
SOURCE: He A et al. J Amer Acad of Dermatol. 2008. doi: 10.1016/j.jaad.2017.12.077.