Activity and physicochemical properties of Photofrin

Upon certain conditions of storage, Photofrin samples changed their photodynamic therapy activity in mice. These samples showed similar absorption and high performance liquid chromatography (HPLC) profiles. The Photofrin samples that were active, however, had higher relative fluorescence yields than those which failed. Active and inactive samples also had different characteristics when analyzed by gel filtration chromatography using Sephacryl S-300; the failed samples had 60% or more high-molecular-weight fraction. The change of the amount of this high-molecular-weight fraction with the time of storage at room temperature could be clearly demonstrated. Results from fluorescence, HPLC and mass spectrometry studies suggest that the high-molecular-weight fraction may form by dehydration from or condensation between various components of Photofrin.