Pharmacokinetics of a Fluorescent Drug Using Laser-induced Fluorescence

Laser-induced fluorescence has been used to measure tissue levels of chloroaluminum sulfonated phthalocyanine in vivo in an implanted hamster cheek pouch carcinoma tumor model. The drug was excited at 610 nm via a pulsed nitrogen laser-pumped dye laser, and fluorescence intensity was monitored at 684 nm for up to 30 days after drug administration. Data were acquired noninvasively with high temporal and spatial resolution using the laser-induced fluorescence apparatus and were analyzed with a multicompartment pharmacokinetic model. In addition, our published data on a C6-BAG glioma rat brain tumor model were analyzed to illustrate the effect of different tumor models on the rates. The rates extracted from the pharmacokinetic model elucidate the mechanisms of drug uptake and retention in the cheek pouch and brain tumor models. The laser-induced fluorescence approach should lead to better drug dosimetry for photochemotherapy and allow quick characterization of the pharmacokinetics of new photosensitizers in tissue.