Stabilization of radiopharmaceutical compositions using hydrophilic thioethers

A composition comprising:

• (1) a radiopharmaceutical precursor comprising a chelator not covalently linked to a targeting moiety or domain;
• and (2) a stabilizing amount of a hydrophilic thioether of the formula
• R—S—CH2C(R1R2R3)
• wherein:
• R is C1 to C4 alkyl or a C1 to C4 alkyl containing at least one hydrophilic group selected from —COOH, —NH2, —NHR4, —NR42, —OH, —SO2R4, —SOR4, —SO3H, —CONH2, —CONHR4, —CONR42, —COOR4, —OR4, —SR4, —NO2, —SO2NH2, —SO2NHR4 and —SO2NR42;
• with the proviso that, when R is methyl, the hydrophilic group is not —NH2, —NHR4, NR42 or —OH;
• R1, R2, and R3 are each independently selected from the group consisting of —H, —COOH, —NH2, —NHR4, —NR42, —OH, —SO2R4, —SO3R4, —SO3H, —CONH2, —CONHR4, —CONR42, —COOR4, —OR4, —SR4, —NO2, —SO2NH2, —SO2NHR4, —SO2NR42, C1 to C4 alkyl, and a C1 to C3 alkyl containing at least one hydrophilic group selected from —COOH, —NH2, —NHR4, —NR42, —OH, —SO2R4, —SO3R4, —SO3H, —CONH2, —CONHR4, —CONR42, —COOR4, —OR4, —SR4, —NO2, —SO2NH2, —SO2NHR4 and —SO2NR42;
• with the proviso that only one of R1, R2, and R3 is —NH2, —NHR4, —NR42 or —OH;
• and
• R4 is selected from the group consisting of C1 to C3 alkyl;
• and with the further proviso that the hydrophilic thioether comprise at least one of said hydrophilic groups.