Identification of Human UDP-Glucuronosyltransferase and Sulfotransferase as Responsible for the Metabolism of Dotinurad, a Novel Selective Urate Reabsorption Inhibitor.

Dotinurad, a novel selective urate reabsorption inhibitor, is used to treat hyperuricemia. In humans, orally administered dotinurad is excreted mainly as glucuronide and sulfate conjugates in urine. To identify the isoforms of UDP-glucuronosyltransferase (UGT) and sulfotransferase (SULT) involved in dotinurad glucuronidation and sulfation, microsome and cytosol fractions of liver, intestine, kidney, and lung tissues (cytosol only) were analyzed along with recombinant human UGT and SULT isoforms. Dotinurad was mainly metabolized to its glucuronide conjugate by human liver microsomes (HLMs), and the glucuronidation followed the two-enzyme Michaelis-Menten equation. Among the recombinant human UGT isoforms expressed in the liver, UGT1A1, UGT1A3, UGT1A9, and UGT2B7 catalyzed dotinurad glucuronidation. Based on inhibition analysis using HLMs, bilirubin, imipramine, and diflunisal decreased glucuronosyltransferase activities by 45.5%, 22.3%, and 22.2%, respectively. Diflunisal and 3'-azido-3'-deoxythymidine, in the presence of 1% bovine serum albumin, decreased glucuronosyltransferase activities by 21.1% and 13.4%, respectively. Dotinurad was metabolized to its sulfate conjugate by human liver cytosol (HLC) and human intestinal cytosol (HIC) samples, with the sulfation reaction in HLC samples following the two-enzyme Michaelis-Menten equation and that in HIC samples following the Michaelis-Menten equation. All eight recombinant human SULT isoforms used herein catalyzed dotinurad sulfation. Gavestinel decreased sulfotransferase activity by 15.3% in HLC samples, and salbutamol decreased sulfotransferase activity by 68.4% in HIC samples. These results suggest that dotinurad glucuronidation is catalyzed mainly by UGT1A1, UGT1A3, UGT1A9, and UGT2B7, whereas its sulfation is catalyzed by many SULT isoforms, including SULT1B1 and SULT1A3. SIGNIFICANCE STATEMENT: The identification of enzymes involved in drug metabolism is important to predicting drug-drug interactions (DDIs) and interindividual variability for safe drug use. The present study revealed that dotinurad glucuronidation is catalyzed mainly by UGT1A1, UGT1A3, UGT1A9, and UGT2B7 and that its sulfation is catalyzed by many SULT isoforms, including SULT1B1 and SULT1A3. Therefore, dotinurad, a selective urate reabsorption inhibitor, is considered safe for use with a small risk of DDIs and low interindividual variability.

Ideal pharmacokinetic profile of dotinurad as a selective urate reabsorption inhibitor.

Dotinurad, a novel selective urate reabsorption inhibitor (SURI), has potent inhibitory effects at low doses on the uptake of urate by urate transporter 1 (URAT1, solute carrier family 22 member 12 [SLC22A12]), localized at the apical membrane of renal proximal tubular cells. This study sought to clarify the pharmacokinetic (PK) profile of dotinurad. In rats, monkeys, and humans, the apparent distribution volume (0.257, 0.205, and 0.182 L/kg, respectively) and oral clearance (0.054, 0.037, and 0.013 L·h-1·kg-1, respectively) of dotinurad were very low, whereas plasma and luminal concentrations were adequately maintained at high levels. In addition, species differences were scarcely observed with plasma protein binding of 99.4%. The main metabolite was dotinurad glucuronide (no specific metabolites in humans), and percentage excretion of unchanged dotinurad was low in all the investigated species. The risk of drug interaction with dotinurad was expected to be low, because it weakly inhibits metabolic enzymes such as cytochrome P450 (CYP). In conclusion, low-dose dotinurad exhibited excellent pharmacological effects as well as ideal PK properties as a SURI.

Synthesis and σ receptor affinity of regioisomeric spirocyclic furopyridines.

In order to investigate systematically the effect of the position of the pyridine N-atom on the σ1 receptor affinity four regioisomeric furopyridines 2a-d were synthesized and pharmacologically evaluated. The key steps of the synthesis comprise bromine/lithium exchange at regioisomeric bromopyridinecarbaldehyde acetals 7a-d, subsequent addition to 1-benzylpiperidin-4-one and cyclization. The regioisomeric acetals 7a-d were obtained either by o-metalation of bromopyridines 5b and 5c or by oxidation of bromopicolines 3a and 3d. In radioligand binding studies the regioisomeric furopyridines 2a-d showed 7- to 12-fold lower σ1 affinity than the benzofuran analog 1. The reduced σ1 affinity of the furopyridines 2a-d is explained with the reduced electron density of the pyridine ring. Since the four regioisomeric furopyridines show almost the same σ1 affinity (Ki = 4.9-10 nM), a directed interaction of the pyridine N-atom with the receptor protein can be excluded.

Pyridine analogues of spirocyclic σ1 receptor ligands.

Spirocyclic benzopyrans 2 interact with high affinity and selectivity with σ1 receptors. Bioisosteric replacement of the benzene ring of the benzopyran substructure with the electron rich thiophene ring (3) led to increased σ1 affinity. Herein the synthesis and pharmacological evaluation of electron deficient pyridine bioisosteres 4 are reported. Homologation of the aldehyde 6 to afford the pyridylacetaldehyde derivative 8 was performed by a Wittig reaction. Bromine lithium exchange of the bromopyridine 8, addition to 1-benzylpiperidin-4-one and cyclization led to the spirocyclic pyrranopyridine 10. Hydrogenolytic removal of the N-benzyl moiety of 10 provided the secondary amine 11, which allowed the introduction of various N-substituents (12a-d). Cyclization of the hydroxy acetal 9 with HCl led to various modifications of the substituent in 3'-position. Generally the σ1 affinity of the pyridine derivatives is reduced compared with those of the benzene and thiophene derivatives 2 and 3. However, the relationships between the structure and the σ1 affinity follow the same rules as for the benzene and thiophene derivatives. The most promising σ1 ligand within this class of compounds is the pyranopyridine 15 with a double bond in the pyran ring revealing a Ki-value of 4.6 nM and a very high selectivity (>217-fold) over the σ2 subtype.

Metabolic profile of FYX-051 (4-(5-pyridin-4-yl-1h-[1,2,4]triazol-3-yl)pyridine-2-carbonitrile) in the rat, dog, monkey, and human: identification of N-glucuronides and N-glucosides.

FYX-051, 4-(5-pyridin-4-yl-1H-[1,2,4]triazol-3-yl)pyridine-2-carbonitrile, is a novel xanthine oxidoreductase inhibitor that can be used for the treatment of gout and hyperuricemia. We examined the metabolism of FYX-051 in rats, dogs, monkeys, and human volunteers after the p.o. administration of this inhibitor. The main metabolites in urine were pyridine N-oxide in rats, triazole N-glucoside in dogs, and triazole N-glucuronide in monkeys and humans, respectively. Furthermore, N-glucuronidation and N-glucosidation were characterized by two types of conjugation: triazole N(1)- and N(2)-glucuronidation and N(1)- and N(2)-glucosidation, respectively. N(1)- and N(2)-glucuronidation was observed in each species, whereas N(1)- and N(2)-glucosidation was mainly observed in dogs. With regard to the position of conjugation, N(1)-conjugation was predominant; this resulted in a considerably higher amount of N(1)-conjugate in each species than N(2)-conjugate. The present results indicate that the conjugation reaction observed in FYX-051 metabolism is unique, i.e., N-glucuronidation and N-glucosidation occur at the same position of the triazole ring, resulting in the generation of four different conjugates in mammals. In addition, a urinary profile of FYX-051 metabolites in monkeys and humans was relatively similar; triazole N-glucuronides were mainly excreted in urine.