Absorption, metabolism and excretion of 14 C-emvododstat following repeat daily oral dose administration in human volunteers using a combination of microtracer radioactivity and high radioactivity doses .

Emvododstat is a potent inhibitor of dihydroorotate dehydrogenase and is now in clinical development for the treatment of COVID-19 and acute myeloid leukemia. Since the metabolism and pharmacokinetics of emvododstat in humans is time‑dependent, a repeat dose study design using a combination of microtracer radioactivity and high radioactivity doses was employed to evaluate the metabolism and excretion of emvododstat near steady state. Seven healthy male subjects each received 16 mg/0.3 µCi 14 C-emvododstat daily oral doses for 6 days followed by a 16 mg/100 µCi high radioactivity oral dose on Day 7. Following the last 16 mg/0.3 µCi 14 C‑emvododstat dose on Day 6, total radioactivity in plasma peaked at 6 h post-dose. Following a high radioactivity oral dose (16 mg/100 µCi) of 14 C-emvododstat on Day 7, both whole blood and plasma radioactivity peaked at 6 h, rapidly declined from 6 h to 36 h post-dose, and decreased slowly thereafter with measurable radioactivity at 240 h post-dose. The mean cumulative recovery of the administered dose was 6.0% in urine and 19.9% in feces by 240 h post-dose, and the mean extrapolated recovery to infinity was 37.3% in urine and 56.6% in feces. Similar metabolite profiles were observed after repeat daily microtracer radioactivity oral dosing on Day 6 and after a high radioactivity oral dose on Day 7. Emvododstat was the most abundant circulating component, M443 and O -desmethyl emvododstat glucuronide were the major circulating metabolites; M474 was the most abundant metabolite in urine, while O ‑desmethyl emvododstat was the most abundant metabolite in feces. Significance Statement This study provides a complete set of the absorption, metabolism and excretion data of emvododstat, a potent inhibitor of dihydroorotate dehydrogenase, at close to steady state in healthy human subjects. Resolution of challenges due to slow metabolism and elimination of a lipophilic compound highlighted in this study can be achieved by repeat daily microtracer radioactivity oral dosing followed by a high radioactivity oral dosing at therapeutically relevant doses.