ALLERGIC CONTACT-DERMATITIS FROM DOXEPIN CREAM - ONE-YEAR PATCH TEST CLINIC EXPERIENCE

Background and Design: Several topical antihistamines are known to cau se contact allergy. Premarket predictive patch testing with doxepin cr eam showed it to have ''low risk of irritation and sensitization'' on normal human skin. In our patch test clinic, we routinely test topical preparations, and over a recent 1-year period, we patch-tested doxepi n cream, the standard screening tray, and other topical preparations o n 97 patients with various pruritic dermatoses. When possible, patient s with positive reactions to doxepin cream were patch-tested with its ingredients, and repeated open-application use tests were also perform ed with the product. Results: Seventeen patients had relevant positive patch test reactions to doxepin cream and 80 had negative reactions. In 13 of the 17 patients with positive reactions, the diagnosis of all ergic contact dermatitis to doxepin cream was confirmed by positive pa tch test reactions to both the active ingredient and the whole formula tion of doxepin cream, by an observed positive use test reaction to do xepin cream, or by both. Of 14 patients who completed testing with dox epin cream ingredients, all had positive reactions to the whole formul ation, and 12 had positive reactions to doxepin hydrochloride. Repeate d open-application use tests with doxepin cream on normal skin resulte d in positive eczematous responses in eight of 10 patients. Eight of t he 17 patients had concurrent, relevant positive reactions to other pa tch tests, especially to fabric-finish resins and to ingredients of ot her topical preparations. Many had long-standing dermatitis, and each had used doxepin cream for several days to 1 year. Two patients appear ed to have had systemic contact dermatitis. Conclusions: Diagnostic pa tch test clinic experience illustrates that doxepin cream is a contact sensitizer on inflamed skin. Oral doxepin should be avoided in patien ts with doxepin contact allergy.