Formulation of ⁶⁸Ga BAPEN kit for myocardial positron emission tomography imaging and biodistribution study

Abstract 

Introduction

Tris(4,6-dimethoxysalicylaldimine)-N,N′-bis(3-aminopropyl)-N,N′-ethylenediamine (BAPEN), a tris(salicylaldimine) derivative, is a heart positron emission tomography (PET) agent when labeled with ⁶⁸Ga. However, its labeling requires complicated and time-consuming procedures. In this study, the authors formulated a new BAPEN kit for convenient ⁶⁸Ga labeling.

Methods

BAPEN (0.25 mg) kits were prepared by dispensing its solution in 1 M sodium acetate buffer (pH 5.5) into sterile vials and lyophilization. The prepared kits were labeled with generator-eluted ⁶⁸Ga in 0.1 N HCl. Stability in human serum was tested. Expiration date was determined by accelerated testing according to US Food and Drug Administration guidelines. A Biodistribution study was performed in normal mice after injection via tail vein.

Results

The prepared kits achieved radiolabeling efficiencies in excess of 95% and showed a shelf-life of 98 days at 25°C and 64.3 months at 4°C. ⁶⁸Ga-BAPEN was found to be stable in human serum at 37°C for at least 1 h. Furthermore, a biodistribution study revealed high heart uptake (10.8% ID/g, 1 h).

Conclusions

The authors developed a BAPEN kit for convenient labeling with ⁶⁸Ga. The ⁶⁸Ga-BAPEN showed high stability and excellent biodistribution results in normal mice, which is required for myocardial PET imaging.

Keywords: Kit formulation, (4,6-MeO₂sal)₂BAPEN, Heart imaging, Lipophilic cation, Gallium-68, Ga-68