[Photosensitization by Benoxaprofen (author's transl)].

The antirheumatic drug dl-2-(4-chlorophenyl) -alpha-methyl-5-benzoxazole-acetic acid (benoxaprofen, Coxigon) can induce mild phototoxic immediate reactions of the skin after some hours of sun exposure and sometimes partial onycholysis. In Central Europe the incidence of this side-effect is about 3 and 1%, respectively. In clinical trials and after experimental high-dose UVA-irradiation (45-64 J/cm2) alpha short-lasting skin burning, already beginning during irradiation, and an erythema of up to 2 h duration could be observed after the ingestion of the recommended daily dose of 600 mg. Photosensitization of the skin can safely be inhibited by a UVA -irradiation absorbing sunscreen agent (Contralum ointment) and onycholysis by using an opaque nail varnish. After epicutaneous and intracutaneous application of benoxaprofen, photosensitization did not occur. The pathogenesis of this unusual phototoxic immediate reaction is unknown.