Contact and photocontact allergy to ketoprofen: clinical and experimental study

In the last 3 years, we have studied 10 patients with allergic reactions to topical ketoprofen. We have investigated the sensitization and irritant potential of the drug and the possibility of cross-reactivity with other aryl-propionic non-steroidal anti-inflammatory drugs (ibuproxam, ibuprofen, naproxen, fenoprofen, flubiprofen and tiaprofenic acid). 2 of our patients had contact dermatitis, and the other 8 photocontact dermatitis. One of our patients showed cross-reactivity between ketoprofen and ibuproxam on patch testing. In the photopatch tests, we observed cross-reactivity between ketoprofen and tiaprofenic acid in 2 patients, and cross-reaction between ketoprofen and ibuproxam and flurbiprofen in another case. Experimental studies, including human maximization and photomaximization tests, performed in 20 healthy volunteers, showed a complete absence of sensitization, 3 volunteers showed a marked irritant reaction to ketoprofen (20% pet.) during either maximization (2 cases) or photomaximization (1 case) tests. Although ketoprofen appears not to be a sensitizing agent in human volunteers, the fact that photosensitization to this drug seems to be quite common after topical use suggests that there are some local or individual factors, at present unknown, facilitating the development of allergy.