Human urinary excretion of NC100692, an RGD-peptide for imaging angiogenesis

The 99mTc complex of NC100692 is being evaluated as a diagnostic agent for the detection of angiogenesis. In the present study, human urine samples from a clinical Phase I study were analysed using reversed-phase liquid chromatography coupled with an ion-trap mass spectrometer (LC–MS) in order to estimate the amount of intact NC100692 and any metabolites excreted in urine following intravenous injection of 150 μg 99mTc-NC100692. Only intact NC100692 was observed in these urine samples, no metabolites were detected, in contrast to data earlier reported for rat urine where two metabolites and no NC100692 were observed. Within 4–8 h after injection, 30 ± 6% of the injected NC100692 was excreted in the urine, with the majority (23 ± 5%) recovered within the first hour post-injection. There was good agreement between the calculated urinary recoveries of NC100692 and total radioactivity in urine samples voided approximately 1 h post-injection. NC100692 constituting 98 ± 24% of the total urinary 99mTc recovery indicating that the 99mTc excreted during this period was most likely excreted as 99mTc-NC100692. The ratio of NC100692 to 99mTc decreased in the urine samples as a function of time following injection for all subjects; this change is most likely due to reduced accuracy in the results at low levels of NC100692.