A study of aminolevulinic acid-induced protoporphyrin IX fluorescence kinetics in the canine oral cavity

Background and Objective: 5-Aminolevulinic acid-induced protoporphyrin IX i s a promising photosensitizer that could enhance the spectroscopic contrast between normal and diseased oral tissues. Knowledge of the pharmacokinetic s and effects on tissue type are important for diagnostic and therapeutic p rocedures. Study Design/Materials and Methods: Dogs randomly were administered five do ses of 5-aminolevulinic acid: 5, 25, 50, 75, and 100 mg/kg. The fluorescenc e was recorded from buccal mucosa, gums, tongue, and facial skin using a fi beroptic probe connected to an optical multichannel analyzer. Blood samples were collected for hematologic and serum biochemical analysis, Pharmacokin etic parameters of interest were estimated using a compartmental model. Results: Protoporphyrin fluorescence at all sites reached a peak in 2-6 hou rs, and returned to baseline in 24-31 hours, depending on the dose. Plasma protoporphyrin peaked earlier than oral tissues. Conclusion: The rate of synthesis of protoporphyrin, and its conversion to heme products are dose dependent. Different tissues have different pharmaco kinetic response. Lasers Surg. Med. 26:405-414, 2000. (C) 2000 Wiley-Liss, Inc.