Standardization of the TRUE Test imidazolidinyl urea and diazolidinyl ureapatches

The preservatives imidazolidinyl urea (IMID, Germall 115) and diazolidinyl urea (DU, Germall II) are commonly used in cosmetic products and are well-k nown sensitizers. The aim of the present study was to establish the optimal patch test concentration in hydrophilic dried-in vehicle (TRUE Test) for I MID and DU. 181 patients were included in the study. Of these, 150 were pat ients referred for patch testing, 12 were patients with known allergy to IM ID and 19 were patients with known allergy to DU. 76 consecutive patients a nd the 12 IMID-allergic patients were patch tested with a dilution series I MID (0 to 600 mug/cm(2)), formaldehyde (180 rhog/cm(2)) and DU (200 mug/cm( 2)). 74 consecutive patients and the 19 DU-allergic patients were patch tes ted with a dilution series of DU (0 to 600 mug/cm(2)), formaldehyde (180 mu g/cm) and IMID (200 mug/cm(2)). A positive dose-response relationship was f ound. The number of doubtful reactions decreased with increasing test conce ntrations. No late reactions were observed. A patch test concentration in h ydrophilic dried-in vehicle (TRUE Test) of 600 mug/cm(2) was found to be ad equate and safe for both IMID and DU.