Radiopharmacokinetics, renal clearance and dosimetry of Tc-99m-MAG(3)

Background. Technetium-99m-mercaptoacetyltriglycine ((TC)-T-99m-MAG(3)) is a radiopharmaceutical for tubular function and can be prepared with 99m-tec hnetium and the ligand Bz-MAG(3) (Instituto Nacional de Investigaciones Nuc leares, Mexico City). No radiopharmacokinetic parameters have been found fo r the healthy adult Mexican population with Tc-99m-MAG(3), prepared with th e nationally produced or imported Bz-MAG(3) kit. Methods, The radiopharmacokinetic parameters and the clearance of Tc-99m-MA G(3) in seven healthy Mexican volunteers were determined by the single- and multi-sample methods, Computer programs were used for the calculations. Results. Using several plasma samples from 0-43 min and the BIEXP program, it was shown that (TC)-T-99m-MAG(3) follows a two-compartment model of dist ribution, with an apparent volume in the central compartment Vd(cc) 3.8 + 0 .7 l, a volume of distribution at steady state Vd(ss) 6.7 + 1.01, T-1/2 alp ha = 0.07 + 0.02 h(-1), T-1/2 beta = 0.49 + 0.15 h(-1), mean residence time MRT = 0.60 + 0.17 h and clearance = 208 + 57 (ml/min)/1.73 m(2). In compar ison, the clearance value with a single sample drawn 33 min post-injection and cal culated with Tauxe's formula was 193 +/- 59 (ml/min)/m(2) Conclusions. The 15 mi difference between the two methods is neither statis tically different (p = 0.11) nor important for routine clinical studies. Th e single-sample method is recommended because it is reliable and can be don e at the same time that the dynamic renal scan is acquired. Estimated absor bed radiation dose was calculated for several organs. (C) 1999 IMSS. Publis hed by Elsevier Science Inc.