DISTRIBUTION OF TEMOPORFIN, A NEW PHOTOSENSITIZER FOR THE PHOTODYNAMIC THERAPY OF CANCER, IN A MURINE TUMOR-MODEL

The biodistribution of temoporfin (tetra[m-hydroxyphenyl]chlorin, m-TH PC), a recently developed photosensitizer, was investigated in BALB/c mice. The drug was administered intravenously (0.35-0.75 mu mol/kg) to tumor-free mice or to mice implanted with the Cole 26 colorectal carc inoma. Blood and tissue samples were collected for up to 96 h post-dos e. Drug concentrations were determined by HPLC coupled to photometric detection at 423 nm. Concentrations in blood and liver fell relatively rapidly such that blood concentrations at later time points were belo w the limit of detection. Tumor concentrations rose at first and then remained constant from 24 h. Temoporfin concentrations in some tissues , notably heart and skeletal muscle, declined only slowly when compare d to blood. The tumor: tissue ratios for those organs that showed a mo re rapid decline in temoporfin concentrations were higher at later tim es, whereas in tissues such as muscle the ratio remained relatively co nstant. The organs with the highest tumor:tissue ratios were small int estine (8.6), liver (6.9) and skeletal muscle (5.0).