Are All Gallium Citrate Preparations the Same?

Abstract

Recent studies on brain imaging using 67Ga citrate from three different manufacturers revealed some clinical differences. Using chromatographic techniques, it was found that 67Ga citrate supplied by vendor A clearly differed from those of vendors B and C in mobility. When citrate was added to material of vendor B to bring the final concentration to 25 mg/ml, the chromatographic mobility increased dramatically. Addition of benzyl alcohol had no effect. The mechanisms involved in causing these chromatographic changes are not clear; however, the in vitro variations noted indicate a difference in chemistry which may ultimately affect the distribution and localization of the radiopharmaceutical.

The Relationship of 67Ga Uptake to Citrate Dose, Compared with 67Ga-Chloride and 67Ga-Transferrin in Rodent Tissues and Tumours

“…The normal use of carrier-free 67 Ga implies that citrate is always present in a vast excess. As Waxman et al (9) pointed out, the citrate: 67 Ga ratio is of the order of 10 5 or 10 6 when the injection solution contains 2.5 or 25 mg/ml citrate, depending on the supplier. These ratios are so large, as to be relatively unaffected by the presence of any 67 Zn, the product of the decay of 67 Ga, which would also form citrate complexes.…”

“…The chromatographic behaviour of 67 Ga from different suppliers has been studied and differences were reported (9). Recently, it has been suggested that there is an optimum citrate: chloride ratio for the best tumour uptake of 67 Ga (7).…”