title: Sensitivity to thimerosal and photosensitivity to piroxicam.
abstract: 17 patients allergic to thimerosal, with no previous history of photosensitivity or piroxicam ingestion, 2 patients with piroxicam-induced photosensitivity, and 10 controls were patch or photopatch tested, with 1 or more of the following: thimerosal, thiosalicylic acid, irradiated and non-irradiated solutions of piroxicam alone, L-cysteine alone and piroxicam plus L-cysteine, and piroxicam in petrolatum., The results of the tests supported the hypothesis that there are cross-reactions between thiosalicylic acid and prioxicam, a photosensitizer. The mechanism of the cross-reactions may involve photoproducts of piroxicam and L-cysteine, as patients allergic to thiosalicylic acid, who have positive photopatch tests to piroxicam, also had positive patch tests to the irradiated solution of piroxicam plus L-cysteine.
authors.affiliation: Department of Dermatology, Hospital de Santa Maria, Lisbon, Portugal.
authors.forename: J L
authors.initials: JL
authors.lastname: de Castro
authors.forename: J P
authors.initials: JP
authors.lastname: Freitas
authors.forename: F M
authors.initials: FM
authors.lastname: Brandão
authors.forename: R
authors.initials: R
authors.lastname: Themido
mesh_terms: D000328:Adult; D001565:Benzoates / Q000009:adverse effects / Q000737:chemistry; D003429:Cross Reactions; D003877:Dermatitis, Contact / Q000209:etiology; D004342:Drug Hypersensitivity / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D010328:Patch Tests; D010787:Photosensitivity Disorders / Q000139:chemically induced*; D010894:Piroxicam / Q000009:adverse effects* / Q000737:chemistry; D013438:Sulfhydryl Compounds; D013849:Thimerosal / Q000009:adverse effects* / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D001565:Benzoates; D013438:Sulfhydryl Compounds; D010894:Piroxicam; C026196:2-thiosalicylic acid; D013849:Thimerosal