Development of a simple kit-based method for preparation of pharmaceutical-grade ⁶⁸Ga-DOTATOC

The use of germanium-68 (⁶⁸Ge)/gallium-68 (⁶⁸Ga) generators is still limited when compared with the ⁹⁹Mo/⁹⁹mTc counterpart, mainly because of the absence of commercial kits and a kit-based method for preparing Ga-labelled radiopharmaceuticals in a reliable way. The present study aimed to develop and optimize a reliable direct labelling of DOTATOC with ⁶⁸Ga through a kit-based approach.

A fraction of the eluate of two different ⁶⁸Ge/⁶⁸Ga generators was directly injected into a vial prefilled with precursor, buffer and scavenger (the prototype of a potential lyophilized kit). The vial was directly warmed to 100°C and then buffered with a 1.5 mol/l sodium ascorbate solution. The parameters influencing the reaction were studied and optimized. The efficacy of the method in terms of incorporation yield and quality of the final radiotracer was compared with preparations performed with two commercial automatic synthesizers by applying the tests prescribed in the European Pharmacopeia monograph for ⁶⁸Ga-DOTATOC.

Under optimal conditions, the overall radiochemical yields of the kit-based process were 73±4 and 69±3% not decay-corrected for the IGG100 and itG generator, respectively. The radiochemical purity was 95±3% and the preparations were compliant with all specifications given in the pharmacopoeia monograph.

The feasibility of a kit-based approach for the preparation of ⁶⁸Ga-DOTATOC was proved and a first home-made version of a putative lyophilized kit was proposed.