Stabilization of Tc-99m radiopharmaceuticals by chemical additives

Abstract

The reliability and applicability of the preparation of the three, for nuclear medicine very important, 99mTc-radiopharmaceuticals from the inactive (technetium-cold) kit solutions were tested. Each examined commercial kit was dissolved in saline (0.9% NaCl). The conditions of the storage of the inactive kit solutions till labeling were examined. The main problem is the stablity of the reductant stannous ions which is very difficult to predict. To stabilize and ensure a good quality of the labeled radiopharmaceuticals, ascorbic or gentisic acid were added. It was found that the best results were obtained by keeping the samples frozen at -20ºC. Both stabilizers can be used but for an effective protection much lower concentrations of ascorbic acid are needed. Its concentrations of 12-60 μg/ml of the kit, stabilized dimercaptosuccinate (DMS) and pyrophosphate (PyP) for about 7-8 days. The solution of 2,3-dicarboxypropane- 1,1-diphosphonate (DPD) was found to be stable even without the stabilizer. This could be attributed probably to the chemical nature of this complex. However, in routine praxis the applied procedure demands great care and personel very experienced in radiopharmacy.

Keywords

• radiopharmaceuticals
• technetium-99m
• dimercaptosuccinate
• dicarboxypropane diphosphonate
• pyrophosphate