[Photosensitizing properties of nonsteroidal antirheumatic drugs in the photopatch test]

The non-steroidal anti-inflammatory drugs, aspirin, carprofen, diclofenac, ketoprofen, piroxicam, and tiaprofenic acid, were tested in a standard photopatch test series. The routine irradiation dose was 15 J/cm2 UV-A; in most patients additional test series were exposed to non-erythematogenic doses of UV-B and a combination of UV-B and UV-A. In the photopatch test, there were reactions to tiaprofenic acid in 43 of 175 (24.6%), to carprofen in 21 of 86 (24.4%), to aspirin in 7 of 76 (9.2%), to piroxicam in 7 of 84 (8.3%), to diclofenac in 5 of 75 (6.7%), and to ketoprofen in 2 of 53 (3.8%). In 16 patients positive photopatch test results did not start to develop until after the 3rd test day (between day 7 and day 34). In some cases there were positive reactions within the non-irradiated control series. Most of the positive photopatch test reactions could be elicited by UV-A alone; in some cases, however, combined irradiation with UV-B plus UV-A was necessary to yield positive results; only rarely did positive reactions occur exclusively with UV-B. The high incidence of positive photopatch test reactions to non-steroidal anti-inflammatory drugs is a possible indication of a phototoxic action. However, in some cases a photoallergic pathomechanism seems probable with regard to the development of reactions after the 3rd test day, a high UV-sensitivity in the photopatch threshold test, and the results of the histological evaluation of test reactions in some patients.(ABSTRACT TRUNCATED AT 250 WORDS)