A single‐dose, microtracer study to determine the mass balance of orally administered, 14C‐labeled sweetener in healthy adult men (LB450)

Abstract

The objective of this study was to determine the mass balance recovery of a rare sugar, through measurement of absorption, metabolism, and elimination using 14C radio‐labeled tracer with quantification via liquid scintillation counting and accelerator mass spectrometry (AMS). AMS measures isotope ratios to achieve low detection limits, providing quantification of 14C labeled compounds to low attomole levels. Eight healthy male subjects were housed within a metabolic ward for 1 week. The orally administered 776 nCi [14C(U)]‐rare sugar (99% purity), in a beverage containing 15g of unlabeled sweetener was consumed following a light breakfast. Blood, urine, fecal and expired air samples were collected at baseline and at various time points through168 hr for detection of the radiotracer and potential metabolites. Plasma Cmax occurred ~1.5 hours after dosing. Urinary total radioactivity (TRA) was 48.02‐90.25 % of dose over 168hr of collection. There was one subject with a low urine recovery (48.02%) within the first 12hr, possibly due to a missed collection. Fecal TRA (0‐120hr) was 1.79‐5.65 % of dose. Expired air 14C detection over 6hrs was only 0‐0.05% of dose and considered negligible. Overall, TRA 14C recovery was approximately 90%. High performance liquid chromatographic fractions analyzed with AMS showed the majority of the radiotracer was intact (TRA 80.3% plasma; 83.6% urine; 16% fecal). The 14C‐rare sugar was the most abundant compound in the plasma and excreta, demonstrating that this novel sugar is absorbed, but not metabolized.Grant Funding Source: Research supported by Tate & Lyle, Health and Nutrition Sciences.