TY - JOUR T1 - NC100668, a New Tracer Tested for Imaging of Venous Thromboembolism: Pharmacokinetics and Metabolism in Humans JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 1979 LP - 1984 DO - 10.1124/dmd.106.014126 VL - 35 IS - 11 AU - Kim G. Toft AU - Judith A. Johnson AU - Inger Oulie AU - Tore Skotland Y1 - 2007/11/01 UR - http://dmd.aspetjournals.org/content/35/11/1979.abstract N2 - The 99mTc-complex of NC100668 [Acetyl-Asn-Gln-Glu-Gln-Val-Ser-Pro-Tyr(3-iodo)-Thr-Leu-Leu-Lys-Gly-NC100194] is a new tracer tested for nuclear medical imaging of venous thromboembolism. NC100668 is a 13-amino acid peptide with a Tc-binding chelator [NC100194; -NH-CH2-CH2-N(CH2-CH2-NH-C(CH3)2-C(CH3)=N-OH)2] linked to the C-terminal end. The present study was performed following injection of 99mTc-NC100668 in healthy human volunteers with five dose levels of NC100668 (20-2000 μg) and a constant radioactivity dose. The rate at which the radioactivity was cleared from blood was independent of gender and dose of NC100668; more than half of the 82% urinary clearance of radioactivity was obtained 2 h postinjection. The radioactivity in blood was reduced to 50% of initial values within 12 min; this was followed by a more gradual decrease with a half-life of 1.2 h and a terminal elimination half-life of 10.5 h. The plasma concentration of NC100668 decreased rapidly with an initial half-life of 5 to 10 min. The half-life after this initial phase could be estimated for only two of the subjects in the highest-dose group because the NC100668 concentration in the other samples at these time points was below the limit of detection of the liquid chromatography/mass spectrometry (LC/MS) method. LC/MS analyses of urine samples revealed the identity of two metabolites generated from the C-terminal end of the molecule; Gly-NC100194 was identified as the major metabolite and NC100194 as a minor metabolite. The estimated sum of these two metabolites is in the same magnitude as the recoveries of 99mTc in these samples, indicating that most of the 99mTc excreted in urine is bound to one of these metabolites. The American Society for Pharmacology and Experimental Therapeutics ER -