Absorption, distribution, metabolism and excretion of 14C-Emvododstat following a single oral dose in rats and dogs

Emvododstat is a potent inhibitor of dihydroorotate dehydrogenase and is now in clinical development for the treatment of acute myeloid leukaemia and COVID-19.Following an oral dose administration in Long-Evans rats, ¹⁴C-emvododstat-derived radioactivity was widely distributed throughout the body, with the highest distribution in the endocrine, fatty, and secretory tissues and the lowest in central nervous system.Following a single oral dose of ¹⁴C-emvododstat in rats, 54.7% of the dose was recovered in faeces while less than 0.4% of dose was recovered in urine 7 days post-dose. Emvododstat was the dominant radioactive component in plasma and faeces.Following a single oral dose of ¹⁴C-emvododstat in dogs, 75.2% of the dose was recovered in faeces while 0.5% of dose was recovered in urine 8 days post-dose. Emvododstat was the dominant radioactive component in faeces, while emvododstat and its two metabolites (O-desmethyl emvododstat and emvododstat amide bond hydrolysis product) were the major circulating radioactivity in dog plasma.

In Vitro Metabolism, Pharmacokinetics and Drug Interaction Potentials of Emvododstat, a DHODH Inhibitor

Emvododstat was identified as a potent inhibitor of dihydroorotate dehydrogenase and is now in clinical development for the treatment of acute myeloid leukaemia and COVID-19. The objective of this paper is to evaluate the metabolism, pharmacokinetics, and drug interaction potentials of emvododstat.Emvododstat showed high binding to plasma protein with minimal distribution into blood cells in mouse, rat, dog, monkey, and human whole blood.O-Demethylation followed by glucuronidation appeared to be the major metabolic pathway in rat, dog, monkey, and human hepatocytes. CYP2C8, 2C19, 2D6, and 3A4 were involved in O-desmethyl emvododstat metabolite formation. Both emvododstat and O-desmethyl emvododstat inhibited CYP2D6 activity and induced CYP expression to different extents in vitro.Emvododstat and O-desmethyl emvododstat inhibited BCRP transporter activity but did not inhibit bile salt transporters and other efflux or uptake transporters. Neither emvododstat nor O-desmethyl emvododstat was a substrate for common efflux or uptake transporters investigated.Emvododstat is bioavailable in mice, rats, dogs, and monkeys following a single oral dose. The absorption was generally slow with the mean plasma T_max ranging from 2 to 5 h; plasma exposure of O-desmethyl emvododstat was lower in rodents, but relatively higher in dogs and monkeys.

Ataluren metabolism: Ataluren-O-1β-acyl glucuronide is a stable circulating metabolite in mouse, rat, dog and human

Ataluren is an aromatic acid derivative with a 1,2,4-oxodiazole moiety. Ataluren-O-1β-acyl glucuronide is a prominent circulatory metabolite in mice, rats, dogs, and humans following oral administration of ataluren. The objective of this paper was to evaluate the stability in vitro and in vivo of ataluren-O-1β-acyl glucuronide metabolite. Ultrahigh performance liquid chromatography-mass spectrometry methods were developed to separate and monitor ataluren-O-1β-acyl glucuronide and its possible migration isomers. In vitro stability was assessed in phosphate buffered saline as well as in control rat and human plasma. The disappearance of ataluren-O-1β-acyl glucuronide and the formation of migration isomers were monitored by the ultrahigh performance liquid chromatography-mass spectrometry methods. In vitro, ataluren-O-1β-acyl glucuronide underwent isomerization with an estimated half-life of approximately 1 h. However, ataluren-O-1β-acyl glucuronide was stable and was the only detectable acyl glucuronide following oral administration of ataluren in mice, rats, dogs, and humans using the same analytical methods. Ataluren acyl glucuronide in mouse, rat, dog, and human plasma could be hydrolyzed by β-glucuronidase, further confirming the structure of O-1β-acyl glucuronide. These results demonstrated that ataluren-O-1β-acyl glucuronide did not undergo migration in vivo. No clinical safety concern related to ataluren-O-1β-acyl glucuronide migration has been detected.

Phase 1 Study of Safety, Tolerability, and Pharmacokinetics of PTC299, an Inhibitor of Stress-Regulated Protein Translation

PTC299 is a novel small molecule that specifically blocks the production of protein from selected mRNAs that under certain conditions use noncanonical ribosomal translational pathways. Hypoxia, oncogenic transformation, and viral infections limit normal translation and turn on these noncanonical translation pathways that are sensitive to PTC299. Vascular endothelial cell growth factor (VEGF) is an example of a transcript that is posttranscriptionally regulated. Single doses of PTC299 (0.03 to 3 mg/kg) were administered orally to healthy volunteers in a phase 1 single ascending‐dose study. In a subsequent multiple ascending‐dose study in healthy volunteers, multiple‐dose regimens (0.3 to 1.2 mg/kg twice a day or 1.6 mg/kg 3 times a day for 7 days) were evaluated. PTC299 was well tolerated in these studies. As expected in healthy volunteers, mean plasma VEGF levels did not change. Increases in C_max and AUC of PTC299 were dose‐proportional. The target trough plasma concentration associated with preclinical efficacy was achieved within 7 days at doses of 0.6 mg/kg twice daily and above. These data demonstrate that PTC299 is orally bioavailable and well tolerated and support clinical evaluation of PTC299 in cancer, certain viral infections, or other diseases in which deregulation of translational control is a causal factor.