The Accupatch: A New Patch Testing Device

Abstract

The purpose of this investigation was to determine if a new patch testing device, the Accupatch (Dermx, Inc, Bethlehem, PA), could detect delayed-type hypersensitivity to paraphenylenediamine (PPD), the allergen in permanent hair dye. The PPD-Accupatch is a ready-touse device that has PPD incorporated into the adhesive matrix of the patch. An optimum amount of antigen, length of application, and time of interpretation were examined in five adult subjects with previous positive patch tests to paraphenylenediamine. Accupatches with 0.1%, 0.3%, and 1.0% PPD, control Accupatches without PPD, and Finn Chambers (Epitest Ltd Oy, Hyrulä, Finland) containing 1% PPD in petrolatum were applied to the upper back for 1, 8, 24, and 48 hours. Two drops of mixed permanent hair dye were applied once to the forearm as an open test. The patch and open tests were interpreted at 1, 8, 24, 48, and 96 hours. The Accupatch compared favorably with the Finn Chamber. The 1% PPD-Accupatch applied for 8 hours and read at 24 hours was a satisfactory dose, application time, and interpretation time for detecting PPD sensitivity in the four subjects who had a relevant history of PPD sensitivity. The open test was negative in four subjects. This preliminary study demonstrated that the PPD-Accupatch was a sensitive, easy-to-use device to detect PPD sensitivity in previously sensitized subjects.