关于神经受体显像药物“比活度”的讨论

A DISCUSSION ABOUT THE“SPECIFIC ACTIVITY” OF RADIONUCLIDE-LABELED NEURO-RECEPTOR IMAGING AGENTS

一个好的神经受体显像药物应满足以下条件:(1)有合适的核素;(2)在靶器官中有足够高的浓聚及较长时间的滞留;(3)药物对受体有高的亲和力和特异性;(4)高的比活度。

The specific activity is an i mportant index of radioiodine-labeled neuro-receptor imaging agents. If no stable nuclide is introduced in the course of preparation, the specific activity of the product is dependent on the specific activity of radioisotope source. However the unlabeled precursor in the final product may reduce the effective specific activity of the products unless it has been removed,, Thus we suggest to use 'apparent specific activity' instead of 'specific activity' . Using 'A_(SA)' , we could approximately evaluate the effect of unreacted precursor on the specific activity of products. In the preparation of neuro--receptor imaging agents it may be very useful.