Photosensitivity induced by quinidine sulfate: experimental reproduction of skin lesions

A case of quinidine sulfate-induced photodermatitis is reported. The photosensitive reaction to quinidine sulfate was reproducible in the photopatch test and after oral intake plus ultraviolet A (UVA) irradiation. Eczematous dermatitis was provoked after intradermal injection of in vitro UVA-irradiated quinidine sulfate only in the presence of patient's serum. The clinical picture and histology suggest an allergic reaction. The photobinding of quinidine sulfate to a potential carrier protein in skin or serum seems to be of crucial importance for this type of photodermatitis. Quinidine sulfate is frequently used as an antiarrhythmic drug. Its potential as a photosensitizer should always be considered.