Phototoxic lesions induced by quinolone antibacterial agents in auricular skin and retina of albino mice.

The phototoxic effects of quinolone antimicrobial agents on mouse auricular skin and retina were examined histologically. Sparfloxacin at 50 or 100 mg/kg, which alone causes no histologic change, was orally administered to albino Balb/c mice, which were irradiated with ultraviolet A for 4 hr immediately after administration. In the auricle, degeneration of basal epidermal cells was sporadically observed at 2 hr (during the irradiation). Foci of slight edema with degenerated fibroblasts were seen in the dermis at 4 hr. Edema and neutrophil infiltration in the dermis became severe up to 96 hr. Initial changes in the retina were observed at 2 hr. Vacuolation of the photoreceptor segments (particularly the inner segment) was occasionally associated with swelling of retinal pigment epithelial cells. The segments became disorganized with time, and the outer nuclear layer showed reduced cellularity. The segments and layer were partially thinned and lost 96 hr later. Enoxacin at 400 and 800 mg/kg induced similar lesions to those of sparfloxacin. Levofloxacin caused similar lesions in the auricle but no change in the retina. The combination of oral administration of quinolone and ultraviolet A irradiation, which never caused apparent morphological changes alone, was shown to be able to induce phototoxic lesions in albino mice. Therefore, this method is thought to be useful to examine morphological changes caused by quinolone phototoxicity.