[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 9mTc-radiopharmaceuticals: 99mTc-2,3-dicarboxypropane-1, 1-diphosphonic acid, 99mTc-meso-2,3-dimercaptosuccinic acid, 9mTc-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 99Tc-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.