[TC99M]TEBOROXIME AND [TC99M]CL(DMG)3B2MP - BINDING CHARACTERISTICS AND METABOLISM OF 2 [TC99M]BATOS IN BLOOD AND TISSUES

Studies were performed in vitro and in vivo to evaluate the binding pr operties and metabolism of [Tc-99m]Cl(CDO)3BMe (Teboroxime) and [Tc-99 m]Cl(DMG)3B2MP in blood and target tissues of rats. Both radiopharmace uticals displayed rapid binding (within 1-3 min) with high affinity to plasma proteins and blood cells. The amounts of radioactivity associa ted with blood components became progressively greater with time of ex posure to either compound. There was a higher proportion of the radiop harmaceuticals associated with blood components during in vivo conditi ons, likely due, at least in part, to clearance of the free fraction f rom the plasma pool. Exposure of both compounds to blood results in ax ial ligand exchange of the chloro atom to a hydroxyl. The results sugg est that it is the free species that is extracted primarily by tissues .