Clinical Pharmacokinetics of Daprodustat: Results of an Absorption, Distribution, and Excretion Study With Intravenous Microtracer and Concomitant Oral Doses for Bioavailability Determination

Mechanistic Determinants of Daprodustat Drug-Drug Interactions and Pharmacokinetics in Hepatic Dysfunction and Chronic Kidney Disease: Significance of OATP1B-CYP2C8 Interplay

Daprodustat is the first oral hypoxia-inducible factor prolyl hydroxylase inhibitor approved recently for the treatment of anemia caused by chronic kidney disease (CKD) in adults receiving dialysis. We evaluated the role of organic anion transporting polypeptide (OATP)1B-mediated hepatic uptake transport in the pharmacokinetics (PKs) of daprodustat using in vitro and in vivo studies, and physiologically-based PK (PBPK) modeling of its drug-drug interactions (DDIs) with inhibitor drugs. In vitro, daprodustat showed specific transport by OATP1B1/1B3 in the transfected cell systems and primary human and monkey hepatocytes. A single-dose oral rifampin (OATP1B inhibitor) reduced daprodustat intravenous clearance by a notable 9.9 ± 1.2-fold (P < 0.05) in cynomolgus monkeys. Correspondingly, volume of distribution at steady-state was also reduced by 5.0 ± 1.1-fold, whereas the half-life change was minimal (1.5-fold), corroborating daprodustat hepatic uptake inhibition by rifampin. A PBPK model accounting for OATP1B-CYP2C8 interplay was developed, which well described daprodustat PK and DDIs with gemfibrozil (CYP2C8 and OATP1B inhibitor) and trimethoprim (weak CYP2C8 inhibitor) within 25% error of the observed data in healthy subjects. About 18-fold increase in daprodustat area under the curve (AUC) following gemfibrozil treatment was found to be associated with strong CYP2C8 inhibition and moderate OATP1B inhibition. Moreover, PK modulation in hepatic dysfunction and subjects with CKD, in comparison to healthy control, was well-captured by the model. CYP2C8 and/or OATP1B inhibitor drugs (e.g., gemfibrozil, clopidogrel, rifampin, and cyclosporine) were predicted to perpetrate moderate-to-strong DDIs in healthy subjects, as well as, in target CKD population. Daprodustat can be used as a sensitive CYP2C8 index substrate in the absence of OATP1B modulation.

Daprodustat

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Investigation of the human metabolism and disposition of the prolyl hydrolase inhibitor daprodustat using IV microtracer with Entero-Test bile string

Daprodustat is an oral small molecule hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor (PHI) approved in Japan and the United States for the treatment of anemia associated with chronic kidney disease. This phase 1, nonrandomized, 2-period, crossover study in 6 healthy men characterized and quantified the metabolites generated after a microtracer IV infusion of 50 μg (125 nCi) [14 C]-daprodustat administered concomitantly with a nonradiolabeled therapeutic dose of a 6-mg daprodustat tablet, followed by a single oral solution dose of 25 mg (62.5 μCi) [14 C]-daprodustat. High-performance liquid chromatography (HPLC) coupled with radioactivity detection (TopCount or AMS) and HPLC-tandem mass spectrometry (HPLC-MSn ) were used for quantitative measurement and structural identification of radioactive metabolites in plasma, urine, feces, and bile. Following oral administration of [14 C]-daprodustat, unchanged daprodustat was the principal circulating drug-related component, accounting for 40% of plasma radioactivity. Predominant oxidative metabolites M2, M3, M4, and M13 individually represented 6-8% of the plasma radioactivity and together accounted for the majority of radioactivity in urine and feces (53% in both matrices; 12% and 41% of dose, respectively). Unchanged daprodustat was not detected in urine and was only 0.7% of total radioactivity in feces (<0.5% of dose), with the remainder of the dose accounted for by oxidative metabolites. The radio-metabolic profile of duodenal bile following IV infusion of [14 C]-daprodustat was similar to that observed in feces after oral administration. The data suggested that oral daprodustat was extensively absorbed, cleared exclusively by oxidative metabolism, and eliminated via hepatobiliary (primary) and urinary (secondary) excretion.

First evidence of the incorporation of daprodustat and other hypoxia-inducible factor stabilizers into equine hair by passive transfer based on segmental quantitative analysis

Daprodustat is a hypoxia-inducible factor prolyl hydroxylase domain (HIF-PHD) inhibitor and is used as an erythropoiesis stimulant for the treatment of anemia in humans. In general, administering daprodustat to horses will result in a lifetime ban from both equestrian sports and horseracing by the International Federation of Horseracing Authorities and the Fédération Équestre Internationale, respectively. To control the misuse/abuse of daprodustat, we conducted nasoesophageal administration of daprodustat (100 mg/day for 3 days) to three thoroughbred mares and the post-administration hair samples collected from the three horses over 6 months were analyzed to demonstrate the potential longer-term detection of daprodustat and its metabolites in hair compared with the detection times of daprodustat of 1 and 2 weeks in plasma and urine respectively. The results of the quantitative 2-cm segmental analysis showed that daprodustat was primarily localized in the proximal region (0-2 cm) at 0.375-0.463 pg/mg at 1 month post-administration. These drug bands were gradually spread out along the hair shaft at a rate consistent with the reported growth rate of horse mane hair (approximately 2.5 cm/month) over the following 6 months. In addition, to attain deeper insight into the mechanism of drug incorporation into hair, a total of 11 relevant parameters, including the actual PK parameters and simulated physicochemical and biopharmaceutical parameters for three HIF stabilizers (i.e., daprodustat, vadadustat, and IOX4), were investigated after normalization of the z-scores of all these parameters. Multiple regression analysis indicated that the major factors contributing to the incorporation of the three drugs into hair were their maximum plasma concentrations and lipophilicities, strongly suggesting that the three HIF stabilizers permeated from the bloodstream into the hair bulb via passive transfer with concentration gradients. This work is the first reported evidence showing the incorporation of HIF stabilizers into hair via passive transfer. In addition, cross-species comparison of drug incorporations into hair between daprodustat in horse and roxadustat in human was made in order to have a better understanding of the interactive interpretations about the analysis results obtained from different species. The above findings are not only useful and beneficial for the purpose of doping control but also provide a better understanding of the mechanism of drug incorporation into horse hair.

Comparison of Two Manufacturing Processes of Daprodustat for Bioequivalence and Dissolution in Healthy Volunteers: A Randomized Crossover Study

Daprodustat, an orally bioavailable hypoxia-inducible factor-prolyl hydroxylase enzyme inhibitor, has recently completed phase 3 clinical development for treating anemia of chronic kidney disease. Part A of this 2-part, randomized, double-blind, single-dose, cross-over study (NCT04640311) compared pharmacokinetic properties of a single oral dose of daprodustat 4 mg tablets manufactured via twin-screw wet granulation (process 1) to 2 sets of 4 mg tablets manufactured via high-shear wet granulation (process 2), to assess the impact of different dissolution profiles on pharmacokinetics. Part B assessed the bioequivalence of daprodustat tablets manufactured via process 1 with tablets manufactured via process 2 at 5 different dose strengths (1, 2, 4, 6, and 8 mg). In part A, mean plasma concentrations of daprodustat were comparable over a 24-hour period despite differences in manufacturing processes and dissolution profiles. In part B, the 90% confidence intervals of the ratios of the least squared means for area under the concentration-time curve and maximum observed plasma concentration fell within the 0.8-1.25 bioequivalence range for all doses, except for maximum observed plasma concentration at 8 mg. A prespecified sensitivity analysis jointly assessing all doses showed bioequivalence for all doses tested. No new safety concerns for daprodustat were identified.

Pharmacokinetics of Daprodustat and Metabolites in Individuals with Normal and Impaired Hepatic Function

Daprodustat is a hypoxia‐inducible factor‐prolyl hydroxylase inhibitor in development for treatment of anemia of chronic kidney disease. We evaluated the role of hepatic impairment on daprodustat pharmacokinetics, pharmacodynamics, and tolerability. Participants with mild (Child‐Pugh Class A, score 5‒6) and moderate (Child‐Pugh Class B, score 7‒9) hepatic impairment and matched healthy controls were administered single 6‐mg doses of daprodustat. Exposure parameters were determined for daprodustat and its six metabolites. Comparisons resulted in 1.5‐ and 2.0‐fold higher daprodustat C_max and area under the curve (AUC) exposures in participants with mild and moderate hepatic impairment, respectively, versus controls; C_max in mild hepatic impairment was comparable to controls. Similarly, aligned with parent drug, unbound daprodustat C_max and AUC exposures increased 1.6‐ to 2.3‐fold in hepatic‐impaired participants versus controls, and metabolite exposures were 1.2‐ to 2.0‐fold higher in participants with hepatic impairment. Erythropoeitin (EPO) baseline‐corrected AUC exposures were between 0.3‐fold lower and 2.2‐fold higher in matched controls versus hepatic‐impaired participants. No serious or study drug‐related adverse events were reported. Daprodustat exposure was increased in participants with moderate and mild hepatic impairment compared with matched controls; however, no meaningful differences in EPO were observed and no new safety concerns were identified (ClinicalTrials.gov: NCT03223337).