Influence of Storage Temperature on Radiochemical Purity of ^99mTc-Radiopharmaceuticals

The influence of effective room temperature on the radiochemical purity of ^99mTc-radiopharmaceuticals was reported. This study was born from the observation that in the isolators used for the preparation of the ^99mTc-radiopharmaceuticals the temperatures can be higher than those reported in the commercial illustrative leaflets of the kits. This is due, in particular, to the small size of the work area, the presence of instruments for heating, the continuous activation of air filtration, in addition to the fact that the environment of the isolator used for the ^99mTc-radiopharmaceuticals preparation and storage is completely isolated and not conditioned. A total of 244 ^99mTc-radiopharmaceutical preparations (seven different types) have been tested and the radiochemical purity was checked at the end of preparation and until the expiry time. Moreover, we found that the mean temperature into the isolator was significantly higher than 25 °C, the temperature, in general, required for the preparation and storage of ^99mTc-radiopharmaceuticals. Results confirmed the radiochemical stability of radiopharmaceutical products. However, as required in the field of quality assurance, the impact that different conditions than those required by the manufacturer on the radiopharmaceuticals quality have to be verified before human administration.