99mTc-Labeling of a hydrazinonicotinamide-conjugated LTB(4) receptor antagonist useful for imaging infection and inflammation.

This report describes the (99m)Tc labeling of a hydrazinonicotinamide (HYNIC)-conjugated LTB(4) receptor antagonist (SG380). The ternary ligand technetium complex [(99m)Tc(SG38)(tricine)(TPPTS)] (RP517) was prepared using a non-SnCl(2)-containing formulation ((2001) J. Pharm. Sci. 90, 114-123). Unlike other HYNIC-conjugated small biomolecules, SG380 is lipophilic and has low solubility in the kit matrix. Using a combination of a solubilizing agent (Lysolecithin) and a cosolvent (ethanol), we have developed a new formulation for routine preparation of RP517. Using this formulation, RP517 can be prepared in high radiochemical purity (RCP > 90%) and remains stable in the kit matrix for at least 6 h. We also prepared the corresponding (99)Tc analogue, [(99)Tc]RP517. An HPLC concordance experiment using RP517 and [(99)Tc]RP517 showed that the same technetium complex was prepared at both the tracer and macroscopic levels. The LC-MS data are completely consistent with the 1:1:1:1 composition for Tc:SG380:tricine:TPPTS.