TUMOR MODEL STUDIES OF TETRACYCLINE-I-131 AND OTHER COMPOUNDS

  • 1 January 1976
    • journal article
    • research article
    • Vol. 17  (4) , 274-281
Abstract
131I-tetracycline (131I-TET) was prepared by allowing tetracycline hydrochloride to react with radioiodide in acidic methanol (labeling efficiency > 85%). This preparation was stable at -4.degree. C for at least 72 h. Some minimal in vivo breakdown occurred. 131I-TET, 67Ga and several 99mTc compounds were studied in a rat hepatoma model. The incorporation of the radiopharmaceuticals into the tumor occurred rapidly, with peak levels at 0.5 and 24 h after injection for 131I-TET and 67Ga, respectively. Clearance of the radiopharmaceutical from nonviable tumor was slower than for viable tumor, and by 72 h after injection the greatest concentration of radioactivity appeared in the nonviable fraction. All normal tissues showed faster clearance than tumor tissue, regardless of viability. Decreasing the quantity of 131I-TET injected increased the percent of uptake in nonviable tumor tissue but had no effect on viable tumor uptake. Of the 99mTc compounds studied, the phosphates developed the highest tumor-to-background ratios. Unfortunately these ratios were not as high as those achieved for 67Ga or 131I-TET.

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