title: Euxyl K 400: incidence of sensitization, patch test concentration and vehicle.
abstract: The aim of this study was to verify the most suitable vehicle and concentration for testing Euxyl K 400 and its individual ingredients, and to evaluate the prevalence of sensitization to this preservative over the years in Italy. From January 1991 to October 1994, Euxyl K 2.5% pet. was positive in 99 patients (35 male, 64 female) out of 3455 (2.8%). Of these, 22 out of 855 patients had a positive reaction during 1991 (2.6%), 29 out of 1037 in 1992 (2.8%), 28 out of 858 in 1993 (3.3%), and 20 out of 705 in 1994 (2.8%). 51 of the 99 patients with a reaction to Euxyl K 400 2.5% pet. showed a positive reaction to dibromodicyanobutane 0.5% pet. and 2 to phenoxyethanol 5% pet. The results of patch testing with serial dilutions of Euxyl K 400 in different vehicles indicate that water is a good vehicle for testing the preservative. However, since Euxyl K 400 is only hydrosoluble to a limited extent, the maximum concentration that can be tested using water is 0.5%, and so with this concentration about 40% of sensitized patients are missed. The results of patch testing with serial dilutions of Euxyl K 400 in petrolatum demonstrate that concentrations lower than 2.5% are not suitable for detection of all sensitized patients. Euxyl K 400 in ethanol frequently causes irritant reactions without offering significant advantages in detecting sensitized patients.
authors.affiliation: Department of Dermatology, University of Bologna, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Tosti
authors.forename: C
authors.initials: C
authors.lastname: Vincenzi
authors.forename: P
authors.initials: P
authors.lastname: Trevisi
authors.forename: L
authors.initials: L
authors.lastname: Guerra
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003358:Cosmetics / Q000009:adverse effects; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D009570:Nitriles / Q000009:adverse effects*; D010328:Patch Tests / Q000379:methods; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects*; D012680:Sensitivity and Specificity
chemical_list: D003358:Cosmetics; D009570:Nitriles; D011310:Preservatives, Pharmaceutical; C039411:1,2-dibromo-2,4-dicyanobutane