Novel drug form of chlorin e 6

Abstract

Chlorin e 6 has been known to be attractive as photosensitizer (PS) for PDT for long. Its usefulness as a photosensitizing part of photoimmunotoxines for targeted PDT, as a synton for further chemical modification and as a promising PS has been widely recognized. There is a patented procedure at our disposal now allowing for preparation of a stable, well soluble and filtrating form of chlorin e 6 - Photodithazine. The elaborated production technology includes 4 steps. Photodithazine's 1-octanol/phosphate buffer, pH 7.4 partition coefficient (Kp) has been found to be 1.4, indicating that it must be able to localize in the plasma membrane. This may be a partial explanation of its higher photodynamic efficacy in vitro, comparing to Photosense (Al-sulfophthalocyanine) (K p 0.05) and its closeness to Photogem (HpD) (K p 1.5). Photodithazine possesses an intensive absorption band in the long-wave red field of the spectrum (λ max 663 nm, e=3.82x10 4 M -1 cm -1 , borate buffer, pH 9.2 with albumine addition), and a high photocytotoxic efficiency in vitro - 5 μM for EC 65 . Thus, it represents a promising second generation PS.