Sensitivity to thimerosal and photosensitivity to piroxicam |
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Authors: | J. L. Cirne, de Castro ,J. P. Freitas,,F. Mewezes,Brandã o R. Themido |
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Affiliation: | Department of Dermatology, Hospital de Santa Maria, Lisbon, Portugal. |
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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. |
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Keywords: | piroxicam thimerosal thiosalicylic acid L-cystcine photoproducts photosensitivity cross-sensitivity medicaments allergic contact dermatitis |
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