NC100668, A NEW TRACER FOR IMAGING OF VENOUS THROMBOEMBOLISM: DISPOSITION AND METABOLISM IN RATS

ABSTRACT: The NC100668 consists of a 13-amino acid peptide, N-terminally blocked with an acetyl group containing an iodinated tyrosine and coupled to a Tc-chelator (NC100194) via the C-terminal glycine. Using the common three-letter abbreviations for amino acids, the structure of NC100668 is Acetyl-Asn-Gln-Glu-Gln-Val-Ser-ProTyr(3-iodo)-Thr-Leu-Leu-Lys-Gly-NC100194, where NC100194 is represented by the chemical formula -NH-CH 2 -CH 2 -N(CH 2 -CH 2 -NH-C(CH 3 ) 2 -C(CH 3 )ϭN-OH) 2 . The detailed structure is shown in 99m Tc-NC100668 is being developed as a diagnostic radiopharmaceutical for imaging of venous thromboembolism, which is a major health problem with an estimated average annual incidence in the United States exceeding 1 per 1000 Diagnostic radiopharmaceuticals are radioactive substances that are administered to patients. Many of these agents are labeled with the ␥-emitter 99m Tc, which has a half-life of 6.02 h doi:10.1124/dmd.105.006239. ABBREVIATIONS: NC100668, Acetyl-Asn-Gln-Glu-Gln-Val-Ser-Pro-Tyr(3-iodo)-Thr-Leu-Leu-Lys-Gly-NC100194; NC100194, -NH-CH 2 -CH 2 -N(CH 2 -CH 2 -NH-C(CH 3 ) 2 -C(CH 3 )ϭN-OH) 2 ; Fmoc, 9-fluorenyloxycarbonyl; Boc, butyl oxy carbonyl; PyBOP, benzotriazole-1-yl-oxy-tris-pyrrolidinophosphonium hexafluorophosphate; DMF, dimethylformamide; TFA, trifluoroacetic acid; MS, mass spectrometry; HPLC, high-performance liquid chromatography; QWBA, quantitative whole-body autoradiography; SAC, self-absorption coefficient; % ID, percentage of injected dose; LC-MS, liquid chromatography-mass spectrometry; MS/MS, tandem mass spectrometry