Labelling and optimization of PHOTOFRIN registered with 99mTc

PHOTOFRIN registered was labelled with 99mTc using SnCl2.2H2O as reducing agent. Instant thin layer chromatography (ITLC-SG) in 0.05 M NaOH was used for evaluation of radiochemical purity. Labelling efficiency was dependent on various factors that include the ligand/reductant ratio, pH and time of incubation. Therefore, optimum conditions of labelling were also determined. The stability of 99mTc-PHOTOFRIN registered in serum was checked by using fresh human serum. Tissue distribution of 99mTc-PHOTOFRIN registered was evaluated in Sprague Dawley rats. PHOTOFRIN registered was labelled with an efficiency of > 95% under optimum conditions, which were PHOTOFRIN registered: 200 μg, pH: 3-4, SnCl2.2H2O: 15 μg and 30 min incubation at room temperature. The 99mTc-labelled PHOTOFRIN registered remained stable in human serum for 24 h. Biodistribution study in rats revealed maximum concentration of the labelled compound in liver, lungs and spleen at 0.5 h, and significant activity was also seen in the bladder and urine, indicating the mode of urinary excretion of PHOTOFRIN registered. (orig.)