PHOTODYNAMIC DESTRUCTION OF ENDOMETRIAL TISSUE WITH TOPICAL 5-AMINOLEVULINIC ACID IN RATS AND RABBITS

OBJECTIVE: The goal of this study was to determine the optimal paramet ers for photodynamic endometrial destruction with topically applied 5- aminolevulinic acid, a precursor for the endogenous synthesis of the f luorescent photosensitizer protoporphyrin IX. STUDY DESIGN: 5-Aminolev ulinic acid pharmacokinetics were measured in rat and rabbit models by analyzing tissue frozen sections 3 to 12 hours after topical administ ration. Dose-response studies were conducted for 100 to 400 mg/ml 5-am inolevulinic acid. Photodynamic therapy was performed intraluminally, and tissue morphologic features were evaluated 3 and 7 days after trea tment. RESULTS: Peak fluorescence was observed 3 hours after topical a dministration. Glandular fluorescence significantly exceeded stromal a nd myometrial in all studies, particularly for 200 mg/ml 5-aminolevuli nic acid. Histologic studies revealed persistent epithelial destructio n with minimal regeneration. CONCLUSION: Topical 5-aminolevulinic acid photodynamic therapy can be used for highly effective, long-lasting d estruction of endometrial epithelium. However, optical dosimetry can v ary, particularly in the rabbit model, and this appears to have an imp act on long-term reepithelialization.