Topical rose Bengal: Pre‐clinical evaluation of pharmacokinetics and safety

BACKGROUND AND OBJECTIVES: Rose bengal (RB) is a potent photosensitizer that has largely been overlooked as a potential photodynamic therapy (PDT) agent. In this study, the feasibility of topical delivery of RB to the epidermis has been evaluated. STUDY DESIGN/MATERIALS AND METHODS: Topical formulations of RB were assessed on murine and rabbit skin for pharmacokinetic properties, cutaneous toxicity, and photosensitization. RESULTS: Hydrophilic formulations (<or=1% RB) exhibited rapid, selective, uniform delivery to the epidermis, with no significant acute cutaneous toxicity in normal skin. Illumination (532 nm) elicited no acute phototoxicity for light intensities <or=100 mW/cm(2) at a light dose of 100 J/cm(2); use of higher intensities resulted in superficial thermal damage. Repeat treatment of rabbit skin (weekly for four weeks) elicited minor phototoxicity only at the highest concentration (1% RB). CONCLUSIONS: These results indicate that RB is safe for PDT treatment of skin disorders, exhibiting negligible effects in normal skin.