Benzoporphyrin derivative: a potent photosensitizer for photodynamic destruction of rabbit endometrium.

OBJECTIVES: To determine the optimal pharmacokinetic characteristics for photodynamic endometrial destruction using topically applied benzoporphyrin derivative and to evaluate long-term morphologic effects in a rabbit model. METHODS: Benzoporphyrin derivative pharmacokinetics were measured by analyzing frozen tissue sections 1.5-12 hours following topical administration. Photodynamic therapy was induced intraluminally 1.5 hours after drug application, and tissue morphology was evaluated by light and scanning electron microscopy 1 and 4 weeks after treatment. RESULTS: The highest glandular and stromal fluorescence was observed 1.5 hours after topical administration. Relative fluorescence of the endometrial glands significantly exceeded that of stroma and myometrium mainly at 1.5 and 3 hours (P < .0001). Histology revealed persistent epithelial destruction with minimal regeneration. Stroma resembled scar tissue in the majority of sections. The bordering myometrium was loosened and invaded by connective tissue. CONCLUSION: Topically applied benzoporphyrin derivative can be used for highly effective, long-lasting photodynamic destruction of rabbit endometrium. However, optical dosimetry can vary, particularly in the rabbit model, and this appears to affect long-term reepithelialization.