68Ga 'vacuum elution approach' for direct radiolabelling of DOTA-conjugated and NODAGA-conjugated peptides.
OBJECTIVE
The Ge/Ga generator is of increasing interest for clinical PET. The arrival on the market of the pharmaceutical-grade generator, which provides an eluate with chemical and radiochemical purities in conformity with the European Pharmacopeia specifications, makes the direct labelling of vectors possible. The kit formulation strategies using single vial productions can improve the access of hospitals and imaging centres that are not equipped with costly automated synthesis modules to the Ga-radiopharmaceutical production. The manual radiosynthesis of Ga requires handling of a relatively high amount of radioactivity, resulting in a high radiation dose to the hand. Moreover, the elution of the Ga/Ge generator with 5 ml of HCl as recommended by the manufacturer leads to a low Ga concentration, which can decrease the efficiency of the labelling procedure. The aim of our approach is to circumvent these disadvantages and to offer an alternative to the hand elution and labelling for a routine production of Ga-radiopharmaceuticals.


METHODS
A mixture of buffer and peptide was first transferred to an evacuated collection vial. Fixed volume of HCl was adapted to the inlet line of the generator. The elution was then performed by the action of vacuum and the labeling occurs at RT or 95°C.


CONCLUSIONS
The 'vacuum elution approach' developed in this work enables the elution of 95% of the available generator activity with 2.5 ml of eluent, the direct labelling of DOTA-conjugated and NODAGA-conjugated peptides with high radiochemical (>97% for all cases) and radionuclidic (100%) purities without exposure of the hand to radiation during the preparation steps.
aNuclear Medicine Department and DHU FIRE, Bichat Claude Bernard University Hospital bPharmacy Department, Bichat Claude Bernard University Hospital, APHP cUMR 1148 Inserm dFederation de Recherche en Imagerie Multimodale, Paris 7 University, Paris eInserm, U930, François Rabelais University, CHRU, Tours, France.
Rana
R
Ben Azzouna
Sébastien
S
Leygnac
Faisal
F
Al-Shoukr
François
F
Rouzet
Denis
D
Guilloteau
Dominique
D
Le Guludec
D000085:Acetates / Q000737:chemistry; D005710:Gallium Radioisotopes / Q000737:chemistry / Q000302:isolation & purification* / Q000592:standards; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry; D006801:Humans; D007553:Isotope Labeling / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D016273:Occupational Exposure / Q000517:prevention & control; D009842:Oligopeptides / Q000737:chemistry; D049268:Positron-Emission Tomography; D011786:Quality Control; D000069079:Radiation Exposure / Q000517:prevention & control; D011874:Radiometry; D019275:Radiopharmaceuticals / Q000737:chemistry / Q000302:isolation & purification* / Q000592:standards; D014618:Vacuum
C572723:1-(1,3-carboxypropyl)-4,7-carboxymethyl-1,4,7-triazacyclononane; D000085:Acetates; D005710:Gallium Radioisotopes; D006573:Heterocyclic Compounds, 1-Ring; D009842:Oligopeptides; D019275:Radiopharmaceuticals; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid