Laser photodynamic therapy for papilloma viral lesions.

Photodynamic therapy was tested for its therapeutic efficacy in eradicating rabbit papilloma warts. The wild-type viral warts suspension was used to induce treatable papilloma warts in the cutaneous tissue of Dutch Belted rabbits. The photosensitizing agents used intravenously were Photofrin II at 10 mg/kg of body weight and Chlorin e6 monoethylene diamine monohydrochloric acid (Chlorin e6 med HCl) at 1 mg/kg of body weight. The lasers used were an argon-dye laser at 628 and 655 nm and a gold vapor laser at 628 nm. The irradiances of 25 to 180 mW/cm2 were applied topically with an end-on lens optical fiber with total radiant doses of 7.5 to 54 J/cm2. Photofrin II and the argon-dye laser at the highest light dosage (54 J/cm2) and Chlorin e6 monoethylene diamine monohydrochloride administered 2 hours before argon-dye laser irradiation at 655 nm at the highest light dosage (54 J/cm2) produced wart regression. Total wart regression without recurrence was achieved with Photofrin II and the gold vapor laser at all light dosages. The difference observed between the argon-dye laser and the gold vapor laser might be explained by the pulsed nature of the gold vapor laser, with its high-peak powers, some 5000 x the average measured light dose. In this model, the smaller, less cornified lesions were more effectively treated with photodynamic therapy.