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Sensitivity to thimerosal and photosensitivity to piroxicam
J L de Castro1, J P Freitas, F M Brandão
1Department of Dermatology, Hospital de Santa Maria, Lisbon, Portugal.
Contact Dermatitis
|March 1, 1991
Summary
Thiosalicylic acid and piroxicam exhibit cross-reactivity, potentially involving photoproducts. This finding is significant for understanding allergic reactions to these substances.
Area of Science:
- Dermatology
- Photodermatology
- Allergy and Immunology
Background:
- Thimerosal allergy is common, and piroxicam can cause photosensitivity.
- The relationship between thiosalicylic acid, piroxicam, and photosensitivity is not fully understood.
Purpose of the Study:
- To investigate potential cross-reactions between thiosalicylic acid and piroxicam.
- To explore the role of photoproducts in piroxicam-induced photosensitivity.
Main Methods:
- Patch and photopatch testing were performed on patients allergic to thimerosal, those with piroxicam photosensitivity, and controls.
- Various substances including thimerosal, thiosalicylic acid, irradiated and non-irradiated piroxicam solutions, L-cysteine, and piroxicam in petrolatum were used.
Main Results:
- Results supported cross-reactions between thiosalicylic acid and piroxicam.
- Patients with thiosalicylic acid allergy and positive photopatch tests to piroxicam showed positive patch tests to irradiated piroxicam plus L-cysteine.
Conclusions:
- Cross-reactions between thiosalicylic acid and piroxicam are suggested.
- Photoproducts of piroxicam and L-cysteine may mediate these cross-reactions.