[The effect of applied cytotoxic drugs on biological behaviour of 99mTc-radiopharmaceuticals].

Introduction. This study was aimed at investigating the influence of certain cytotoxic drugs on the organ uptake of the following 99mTc-radiopharma­ceuticals: 99mTc-2,3-dicarboxypropane-1,1-diphosphonic acid, 99mTc-meso-2,3-dimercaptosuccinic acid, 99mTc-tin colloid and 99mTc-mac­raggregated albumin. Methotrexate sodium and cyclophosphamide were used as models to evaluate these effects. Material and methods. Two groups of healthy male Wistar rats were treated separately by oral application of the drugs for 7 days. On the eighth day, each of the 99mTc-radiopharmaceuticals was applied in a separate group of treated animals. They were sacrificed at different time intervals and the radioactivity in the organs of interest was measured. The organ uptake of the 99mTc-radiopharmaceuticals in an additional control group of animals was also studied. Results. The results obtained showed an alteration in the organ uptake of 99mTc-radiopharmaceuticals in animals treated with cytotoxic drugs. In the rats treated with methotrexate sodium, there was a higher up­take of 99mTc-meso-2,3-dimercaptosuccinic acid in the bones, stomach and intestine, a higher uptake of 99mTc-2,3-dicarboxypropane-1­,1-diphosphronic acid in the bones, intestine, blood and muscle, a lower uptake of 99mTc-tin colloid in the liver and a lower accumulation of 99mTc-macroaggregated albumin in the lungs. Cyclophospha­mide-treated animals showed enhanced uptake of 99mTc-meso-2,3-dimercaptosuccinic acid in the kidneys, a twofold enhanced uptake of 99mTc-2,3-dicarboxypropane-1,1-diphosphronic acid in all organs except the stomach, a decreased uptake of 99mTc-tin colloid in the lungs, spleen and kidneys and a significantly decreased uptake of 99mTc-macroaggregated albumin in the lungs. Conclusion. These results confirm that both methotrexate sodium and cyclophosphamide may alter the organ uptake of 99mTc-radiopharmaceuticals in experimental animals.