Clinical Evaluation of the Cutaneous Phototoxicity of 5,10,15,20-Tetra (m-hydroxyphenyl)chlorin

ABSTRACT The cutaneous phototoxic reaction induced by intravenous injection of 5,‐10,‐15,‐20‐tetra(m‐hydroxyphenyl)chlorin (mTHPC) has been clinically evaluated in patients undergoing photodynamic therapy. These tests were performed on the backs of 23 patients with a solar simulator at various times after drug administration ranging from 5 h to 57 days. The mTHPC doses ranged from 0.1 to 0.3 mg/kg, and the illuminations lasted from 30 s up to 8 min. These tests have shown that the duration of the skin photosensitization induced after a typical therapeutic dose of mTHPC (0.15 mg/kg) is less important than with Photofrin®(2 mg/kg). The level of mTHPC in the skin was also assessed in vivo and at times corresponding to the irradiations using an optical fiber‐based spectrofiuorometer. This study indicates that the light‐induced fluorescence spectroscopy of mTHPC enables prediction of the degree of photosensitivity of the skin.