The objective of this study was to develop a kit formulation for [99mTcN(mpo)(PNP5)]+ (MPO = 2-mercaptopyridine oxide), (99mTcN-MPO) to support its clinical evaluations as a SPECT radiotracer. Radiolabeling studies were performed using three different formulations (two-vial formulation and single-vial formulations with/without SnCl2) to explore the factors influencing radiochemical purity (RCP) of 99mTcN-MPO. We found that the most important factor affecting the RCP of 99mTcN-MPO was the purity of PNP5. 99mTcN-MPO was prepared >98% RCP (n = 20) using the two-vial formulation. For single-vial formulations with/without SnCl2, β-cyclodextrin (β-CD) is particularly useful as a stabilizer for PNP5. The RCP of 99mTcN-MPO was 95–98% using β-CD, but its RCP was only 90–93% with γ-cyclodextrin (γ-CD). It seems that PNP5 fits better into the inner cavity of β-CD, which forms more stable inclusion complex than γ-CD in the single-vial formulations. The results from biodistribution and imaging studies in Sprague–Dawley rats clearly demonstrated biological equivalence of three different formulations. Single photon-emission computed tomography data suggested that high quality images could be obtained at 0–30-min post-injection without significant interference from the liver radioactivity. Considering the ease for 99mTc-labeling and high RCP of 99mTcN-MPO, the non-SnCl2 single-vial formulation is an attractive choice for future clinical studies.
本研究旨在开发[99mTcN(mpo)(
PNP5)]+(MPO =
2-巯基吡啶氧化物)(99mTcN-MPO)的试剂盒配方,以支持其作为
SPECT 放射性示踪剂的临床评估。我们使用三种不同的制剂(含/不含
氯化锡的双面制剂和单面制剂)进行了放射性标记研究,以探索影响 99mTcN-MPO 放射性
化学纯度(RCP)的因素。我们发现,影响 99mTcN-MPO 放射性
化学纯度的最重要因素是
PNP5 的纯度。使用双层配方制备的 99mTcN-MPO 的 RCP >98% (n = 20)。对于含/不含
氯化锡的单口制剂,β-
环糊精(β-CD)作为
PNP5 的稳定剂特别有用。使用 β-CD 时,99mTcN-MPO 的 RCP 为 95-98%,而使用 γ-
环糊精(γ-CD)时,其 RCP 仅为 90-93%。由此看来,
PNP5 与 β-CD 的内腔更贴合,在单瓶制剂中形成的包涵复合物比 γ-CD 更稳定。在
SPrague-Dawley 大鼠体内进行的
生物分布和成像研究结果清楚地表明了三种不同制剂的
生物等效性。单光子发射计算机断层扫描数据表明,在注射后 0-30 分钟内可以获得高质量的图像,而不会受到肝脏放射性的明显干扰。考虑到 99mTc 标记的简易性和 99mTcN-MPO 的高 RCP,非 SnCl2 单瓶装制剂是未来临床研究的一个有吸引力的选择。