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Development of kit formulations for (99m) TcN-MPO: a cationic radiotracer for myocardial perfusion imaging.

Journal of labelled compounds & radiopharmaceuticals (2014-07-30)
Yumin Zheng, Shundong Ji, Elena Tomaselli, Shuang Liu
ABSTRACT

The objective of this study was to develop a kit formulation for [(99m) TcN(mpo)(PNP5)](+) (MPO = 2-mercaptopyridine oxide), ((99m) TcN-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 (99m) TcN-MPO. We found that the most important factor affecting the RCP of (99m) TcN-MPO was the purity of PNP5. (99m) TcN-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 (99m) TcN-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 (99m) Tc-labeling and high RCP of (99m) TcN-MPO, the non-SnCl2 single-vial formulation is an attractive choice for future clinical studies.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Tin(II) chloride dihydrate, ACS reagent, 98%
Sigma-Aldrich
Tin(II) chloride dihydrate, reagent grade, 98%
Sigma-Aldrich
Tin(II) chloride dihydrate, ≥99.995% trace metals basis
Sigma-Aldrich
Tin(II) chloride dihydrate, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥98%
Supelco
Tin(II) chloride dihydrate, suitable for AAS
Sigma-Aldrich
Tin(II) chloride dihydrate, ≥99.99% trace metals basis