Photocontact allergy due to suprofen

A 79-year-old Japanese woman developed edematous erythema on sun-exposed areas 3 months after applying Sulprotin ointment, which contains 1% suprofen (SP), a phenylacetic acid derivative. A patch test with Sulprotin ointment as it was negative, but a photopatch test with Sulprotein ointment as is was positive. A photopatch test with 10-3% SP was positive, as was that obtained with an SP analogue, 3% ketoprofen, but that with the ointment base of Sulprotin was negative. Photopatch tests with other SP analogues such as flurbiprofen, ibuprofen, and pranoprofen were negative. She developed abnormal erythema with monochromatic irradiation in the range from 320 to 380 nm on the uninvolved abdominal skin where 1% SP had been applied 24 hours (h) before irradiation. The action spectrum for this erythema agreed with the absorption spectrum of SP in the range of UVA. The MED after applying SP was below that after applying w. pet. in the range from 250 to 290 nm and from 300 to 320 nm. Positive intracutaneous test results were obtained with an irradiated mixture of human serum albumin (HSA) and SP at 48 and 72 h after injection and negative ones with a mixture of HSA and irradiated SP.