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 (≤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 ≤100 mW/cm2 at a light dose of 100 J/cm2; 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. Lasers Surg. Med. 32:101–110, 2003. © 2003 Wiley‐Liss, Inc.