EXPERIMENTAL GROUNDS FOR USING CHLORIN E(6) IN THE PHOTODYNAMIC THERAPY OF MALIGNANT-TUMORS

The toxicity, pharmacokinetics and antitumour effect of chlorin e(6) after light irradiation were studied. The LD50 value of chlorin e(6) in C3H mice is 189 +/- 9 mg kg(-1) and in Wistar white rats is 113 +/- 18 mg kg(-1) 14 days after intraperitoneal injection. The concentration of chlorin e(6) in blood, liver, kidney, spleen and tumors (sarcoma M-1 and sarcoma 45) of the rats was determined by a fluorescence method, 3, 6, 12, 18, 24, 48 and 72 h after administration at a dose of 10 mg kg(-1). For this purpose, chlorin e(6) was extracted from tissues by the detergent Triton X-100. The depth of necrosis in sarcoma 45, the regression rate of sarcoma M-1 and the animal cure rate were evaluated after chlorin e(6) administration at doses of 1-10 mg kg(-1) and subsequent irradiation with krypton laser light. Depending on the dose and the time interval between chlorin e(6) injection and irradiation, the depth of necrosis in sarcoma 45 varied from 5.0 to 15.0 mm. The cure rate of the animals with sarcoma M-1 varied from 10% to 60%. The antitumor effect was directly proportional to the chlorin e(6) dose and light energy exposure and inversely proportional to the time interval between photosensitizer injection and irradiation.