The role of additives in moderating the influence of Fe(III) and Cu(II) on the radiochemical yield of [68Ga(DOTATATE)]. (January 2016)

• Record Type: Journal Article
• Authors: Oehlke, Elisabeth; Lengkeek, Nigel A.; So Le, Van; Pellegrini, Paul A.; Greguric, Ivan; Weiner, Ron
• Is Part Of: Applied radiation and isotopes. Volume 107(2016:Jan.)
• Page Start: 13
• Page End: 16
• Publication Date: 2016-01
• Subjects: 68Ga radiolabelling -- DOTATATE -- Metal ion contamination -- Ascorbic acid -- Phosphate -- Additives -- PET.; Radiology -- Periodicals; Radiation -- Industrial applications -- Periodicals; Nuclear chemistry -- Periodicals; Internet resource; Periodical; 660.298
• DOI: 10.1016/j.apradiso.2015.09.008
• Languages: English
• ISSNs: 0969-8043

Abstract

Abstract: [ 68 Ga(DOTATATE)] has demonstrated its clinical usefulness. Both Fe 3+ and Cu 2+, potential contaminants in Gallium-68 generator eluent, substantially reduce the radiochemical (RC) yield of [ 68 Ga(DOTATATE)] if the metal/ligand ratio of 1:1 is exceeded. A variety of compounds were examined for their potential ability to reduce this effect. Most had no effect on RC yield. However, addition of phosphate diminished the influence of Fe 3+ by likely forming an insoluble iron salt. Addition of ascorbic acid reduced Cu 2+ and Fe 3+ to Cu + and Fe 2+ respectively, both of which have limited impact on RC yields. At low ligand amounts (5 nmol DOTATATE), the addition of 30 nmol phosphate (0.19 mM) increased the tolerance of Fe 3+ from 4 nmol to 10 nmol (0.06 mM), while the addition of ascorbic acid allowed high RC yields (>95%) in the presence of 40 nmol Fe 3+ (0.25 mM) and 100 nmol Cu 2+ (0.63 mM). The effect of ascorbic acid was highly pH-dependant, and gave optimal results at pH 3. Highlights: Additives reduce the negative effect of metal ions on the RC yield of [ 68 GaDOTATATE]. Addition of phosphate results in excellent RC yields for a Fe 3+ /ligand ratio of 2:1. Ascorbic acid was more effective with high RC yields for both Fe 3+ and Cu 2+ . The effect of ascorbic acid is highly pH-dependant with optimal results at pH3.