Abstract
A case of photosensitive drug eruption induced by mequitazine is reported. A 46-year-old woman manifested pruritic, scaly erythematous maculopapules on her face, anterior site of neck, upper breast and dorsal site of both hands after the administration of 9mg/day of mequitazine for three days. A patch test performed with 5% mequitazine was positive after 48 hours and a photopatch test with ultraviolet radiation showed increased reactivity. A drug lymphocyte stimulation test was negative. A patch test with 5% mequitazine using 21 control patients showed a positive reactivity in 62%, which means that mequitazine itself is a contact antigen. According to the discrepancy of wave length between absorption and phototoxicity, it is presumed that mequitazine-sulfoxide, which is the main metabolite of mequitazine, contributes to the photosensitivity of mequitazine. Thus both phototoxic and photoallergic mechanisms seem to be related.
