An Evaluation of the Phototoxicity of Tacrolimus (FK506) Ointment in Hairless Mice

The acute phototoxic potential of tacrolimus (FK506) ointment was investigated in Crl:SKH1-hr hairless mice. Response toa series of ultravioletradiation (UVR) site exposures in males (five group) following a single topical administration of tacrolimus ointment (0%[vehicle], 0.03%, 0.1%, 0.3%, 1%, or 3%) indicated that tacrolimus ointment was neither photoprotective or phototoxic. However, a slight but dose-related decrease in body weight relative to the vehicle control was found at the end of the 4-day observation period in the tacrolimus ointment-treated groups. The same concentrations of tacrolimus ointment were applied to the back and sides of mice (five sex group; ∼40% of total body surface area) 5 days week in a 13-week range-finding study to assess the tolerance to the ointment and UVR exposure. Untreated animals served as a control group. Mice were exposed to 72 minutes of UVR from a 6.5-kW xenon lamp. Mortality occurred in the 0.3%, 1%, and 3% ointment groups. Application of 3% tacrolimus ointment...