4 cases of photocontact dermatitis due to ketoprofen

We report 4 cases of photocontact dermatitis due to ketoprofen, a non-stero idal anti-inflammatory drug derived from propionic acid. We carried out a s kin biopsy to examine the amount of ketoprofen in the eruptive skin. We inv estigated the cross-reactions between tiaprofenic acid, suprofen and ketopr ofen by patch and photopatch testing. In case no, 1, 17 days after the disc ontinuance of Mohrus poultice (containing ketoprofen as an active ingredien t), we detected ketoprofen 312.5 ng/g in the area of skin where the poultic e was applied. All 4 cases reacted positively to the causative medicaments containing ketoprofen and ketoprofen 1% pet. 3 out of 4 cases reacted posit ively to tiaprofenic acid 1% pet. Only 1 case out of the ketoprofen and tia profenic acid positive cases reacted positively to suprofen 1% pet. Vehicle s of patients' medicaments were negative in all 4 cases. We suspected that the key structure of the cross-reaction between ketoprofen and tiaprofenic acid and suprofen was the benzoyl radical.