A. Garcia Perez

Is benzoyl peroxide an irritant or sensitizer

Several reports have emphasized the dispanty between the allergic potential of benzoyl peroxide and the low frequency of position patch test reactions. A 23-year-old woman with cystic acne was treated with a 5% topical solution (Peroxiben 5% geJ<Il>). After 7 days, she noted mtolerance, with redness and scaling and severe 1tchmg. When the medication was discontinued, the reaction cleared m 24-48 h, but relapses appeared when a therapy was restarted. She was patch tested with a standard senes, benzoyl peroxide I% pet. and the veh1cle, and was positive to wood tars only. Further patch tests With senal dilutiOns of her Peroxiben were performed, and all showed a strong positive response. Another recent preparation of I% benzoyl peroxide m neutral gel (Gel Neutro O.T.C.<Il>) was also pos1t1ve; the neutral base was negative. Benzoyl peroxide IS one of the most common topIcal compounds prescribed for acne and its capacity to sensitize IS well-known (I, 3, 7-9). However, contact allergy to it m patients with acne IS uncommon (8, 9, 12). There have been many attempts to explam th1s phenomenon. The pilosebaceous umt may generate an mtermediate metabolite (6, 11), the allergen bemg a metabolite seldom formed m facial skm, or perhaps degrade the drug more rapidly (II). Attempts to find metabolites of benzoyl peroxide have not succeeded. Sweatmg could dilute the compound and wash away the product (9). Treatment without occlusive techmques would mm1m1ze the likehood of sensitization (3). The presence of inflammation m acne could mterfere with the mduction of an allergic response (6). On the other hand, several reports (4, 8, 9, 12) have suggested that m many cases, the symptoms of sensitization are mild and they may be regarded merely as 1rntants; thus a patch test 1s not performed. In our case, the prevwusly negative test and the positive response w1th a recent compound, could be explamed by degradation of benzoyl peroxide (2, 5, 10), wh1ch could alter the true sensitizmg rate m the people with acne.

Comparative Spanish multicenter study: TRUE TestTM versus allergens in petrolatum

Epiquick (EPI) is a new ready-to-use patch test system with a set of 5 Finn Chambers on Scanpor tape (FCS), filled with a standardized volume of the test material in pet. (18 ,ul/chamber). The EECDRG performed a multicenter trial comparing this system with the conventional one (Finn Chambers filled with the test materials shortly before use). 19 substances of the European standard series were evaluated in a total of 963 unselected patients at 10 centers. 378 patients (39.2%) had neither irritant nor allergic reactions in both test systems. Irritant reactions were recorded 81 times with EPI and 92 times with FCS. 578 patients (60%) showed at least 1 allergic reaction resulting in a total of 1130 paired skin reactions. Analyzing clearly positive allergic reactions at different reading times, the overall correspondence was good: Epi + /CFS + or Epi/FCS83% (48 h), 73% (72 h) and 82% (96 h). Different patterns of test-reactions (Epi/FCS + or Epi + / FCS-) were seen in 7% to 13%, depending on type of allergen and reading time. There was a tendency for a slightly higher positivity rate with EPI than with FCS. For major allergens, the concordance was excellent (nickel: EPI 87.4%, FCS 83.6%; fragrancemix: EPI 70.4%, FCS 70.4% 96 h readings). In conclusion, EPI is a suitable system for patch testing and yields comparable results to self-filled FCS. Major advantages are standardization of the filling volume and saving of time in the application procedure.