Pharmacokinetics and biodistribution of Photolon® (Fotolon®) in intact and tumor-bearing rats

SummaryBackgroundThis paper provides the results of the non-clinical evaluation of biodistribution of the PS Photolon® in inner organs and tissues of intact and tumor-bearing rats with xenograft tumors of different morphologic types.MethodsThe accumulation studies were performed in rats by means of intravital laser fluorimetry in situ and spectrophotometric determination ex vivo.ResultsThe biodistribution pattern of Photolon® does not depend on tumor carriage as well as on morphologic type of the xenograft tumor. We have also showed that Photolon® easily crosses an intact blood–brain barrier and accumulates in tissues of central nervous system. The relative bioavailability of brain tissues for Photolon® was estimated as 82%, Tmax—30 min, mean residual time (MRT)—1.6 h.ConclusionsIn general, results of the experimental study of biodistribution of Photolon® in inner organs and tissues of rats, performed as in real time (by means of intravital laser fluorimetry in situ) as ex vivo (spectrophotometric assay) can be utilized while optimizing existing regimens of PDT with the purpose to increase safety and efficacy of treatment as well as for the development of new PDT protocols with Photolon® applied for new indications. Parameters of pharmacokinetics and biodistribution of Photolon®/Fotolon® as well as its’ ability to cross an intact blood–brain barrier, are optimal for the majority of modern clinical applications of PDT.