Chemistry of 99mTc tracers. II. In vitro conversion of tagged HEDP and pyrophosphate (bone-seekers) into gluconate (renal agent). Effects of Ca and Fe (ii) on in vivo distribution.

Sodium gluconate transforms the bone-seekers 99mTc-HEDP and 99mTc-pyrophosphate into the renal agent 99mTc-gluconate. In these in vitro processes, pyrophosphate is displaced faster than HEDP, while the HEDP reaction is accelerated by calcium ions. The in vivo distributions of these bone and kidney agents are altered by the prior local injection of calcium or iron(II). These transformation and translocation phenomena are explained in terms of the mechanistic behavior of Tc(IV) complexes.