碘-123-ADAM於大鼠體內之分佈與輻射劑量之計算

Background: The serotonin transporters (SERT) plays an important role in regulating serotonin levels in the synaptic cleft and is one of the major action sites for antidepressant drugs. An (superscript 123)I-labeled tracer, ADAM is a promising agent for imaging SERT with single photon emission computed tomography (SPECT). (superscript 123)I-ADAM imaging can be exploited to investigate the density of SERT in living brain, which may be a valuable tool for diagnosing and monitoring depressed patients. In the present study, radiation dosimetry of this radiopharmaceutical was investigated. Methods: (superscript 123)I-ADAM was prepared through an oxidative iododestannylation reaction. Following the administration of (superscript 123)I-ADAM to 24 SD rats via femoral vein, the animals were sacrificed at different time intervals. Radioactivities of fifteen organs or tissues were measured to calculate the distribution which was expressed in percent injected dose per organ and per gram, respectively. The residence time of (superscript 123)I-ADAM in each organ was applied to estimate the radiation dose in human by using the MIRD 3 program. Results: There was 0.46% of injected dose found in brain at 5 min after injection. The highest absorbed organ dose was found 0.23 mGy/MBq to the upper large intestine. The effect dose and effective dose equivalent were evaluated to be 0.014 mSv/MBq and 0.021 mSv/MBq, respectively. Conclusion: The results suggested that (superscript 123)I-ADAM is a high brain uptake tracer with acceptable radiation dose to the human body.