Evaluation of stannous oxidation in the preparation of ultrahigh-purity 99m Tc(V)-DMSA.
It has been shown previously that renal kit, trivalent technetium-99m dimercaptosuccinic acid [99mTc(III)-DMSA], can be transformed into tumour imaging agent, pentavalent technetium-99m DMSA [99mTc(V)-DMSA], by adding sodium bicarbonate (NaHCO3) and subsequently bubbling with oxygen. However, the purity of this pentavalent preparation was reported to be in the range 83-94% at best. In this study, the preparation of ultrahigh-purity 99mTc(V)-DMSA is described, and the role of stannous oxidation in the conversion of 99mTc(III)-DMSA to 99mTc(V)-DMSA is evaluated in order to understand the underlying mechanism. The results show that controlled oxygen bubbling increases the 99mTc(V)-DMSA levels, with a concomitant decrease in the 99mTc(III)-DMSA levels, in a time-dependent pattern. The purity of the pentavalent DMSA is shown to be consistently very high (>99%), as estimated by chromatography, and this correlates very well with the minimal or no renal uptake of this compound in patient studies.
Kumar
V
V
Department of Nuclear Medicine and Ultrasound, Westmead Hospital, Sydney, Australia. nvk@imag.wsahs.nsw.gov.au
D004355:Drug Stability; D006801:Humans; D007700:Kinetics; D009369:Neoplasms / Q000000981:diagnostic imaging; D010084:Oxidation-Reduction; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000737:chemistry / Q000493:pharmacokinetics; D011933:Reagent Kits, Diagnostic; D017693:Sodium Bicarbonate; D019783:Technetium Tc 99m Dimercaptosuccinic Acid / Q000737:chemistry* / Q000493:pharmacokinetics; D014018:Tissue Distribution
D019275:Radiopharmaceuticals; D011933:Reagent Kits, Diagnostic; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D017693:Sodium Bicarbonate