Pharmacokinetics of Edoxaban 15 mg in Very Elderly Patients with Nonvalvular Atrial Fibrillation: A Subanalysis of the ELDERCARE-AF Study.

BACKGROUND: We evaluated the pharmacokinetics (PK) of low-dose (15 mg) edoxaban in very elderly patients (≥80 years) with nonvalvular atrial fibrillation (NVAF) and high bleeding risk. METHODS: This subanalysis of the phase 3, randomized, double-blind, placebo-controlled, multicenter ELDERCARE-AF study evaluated edoxaban plasma concentrations and compared them with the Japanese population of the ENGAGE AF-TIMI 48 and Japanese severe renal impairment (SRI) studies. RESULTS: The PK analysis population included 451 patients, 53.8% of whom concomitantly used antiplatelet drugs, 41.0% had SRI, and 38.0% had low body weight. Edoxaban plasma concentrations at trough and 1 to 3 hours post-dose in ELDERCARE-AF were 17.3 ± 13.9 (n = 427) and 93.3 ± 57.8 ng/mL (n = 447), respectively. These values were slightly higher than the 15 mg group in ENGAGE AF-TIMI 48 (n = 79; 12.4 ± 12.1 and n = 115; 78.7 ± 45.0 ng/mL, respectively), lower than the ENGAGE AF-TIMI 48 high-dose reduced to 30 mg group (n = 83; 25.1 ± 36.6 and n = 111; 150 ± 91.6 ng/mL, respectively), but similar to the Japanese SRI study (n = 39; 18.4 ± 11.2 and n = 40; 96.8 ± 48.3 ng/mL, respectively). ELDERCARE-AF patients with SRI and low body weight (≤45 kg) had higher concentrations than those without, and those taking antiplatelet drugs had lower concentrations than those who were not. CONCLUSION: PK data support edoxaban 15 mg once daily for very elderly NVAF patients with high bleeding risk, with caution for patients with SRI and/or low body weight.

Bioequivalence of Esaxerenone Conventional Tablet and Orally Disintegrating Tablet: Two Single-Dose Crossover Studies in Healthy Japanese Men.

We assessed the bioequivalence of a single dose of 5-mg of esaxerenone administered as an orally disintegrating tablet (ODT) with the conventional oral tablet in healthy Japanese men. This single-center, open-label, randomized, two-drug, two-stage crossover, single-dose study was conducted in two parts. In study 1, both formulations were taken with water. In study 2, only the ODT formulation was taken without water. The primary outcome was the evaluation of bioequivalence of the ODT and conventional tablet using the pharmacokinetic (PK) parameters maximum plasma concentration (Cmax ) and area under the plasma concentration-time curve to the last quantifiable time (AUClast ). Plasma concentrations were measured using a validated liquid chromatography/mass spectrometry method and PK parameters were calculated by noncompartmental analysis. The ratios of the geometric least-squares mean (2-sided 90% confidence intervals [90%CIs]) for ODT with (study 1) and without (study 2) water to the conventional tablet were 1.03 (1.00-1.07) and 1.01 (0.96-1.06) for Cmax and 1.03 (1.00-1.07) and 0.96 (0.94-0.98) for AUClast , respectively. The 90%CIs fell within the predefined bioequivalence range of 0.80-1.25. Treatment-emergent adverse events were similar between both formulations. In conclusion, esaxerenone 5-mg ODT taken with or without water was bioequivalent to a single 5-mg conventional oral tablet.

Physiologically based pharmacokinetic modelling to predict the clinical effect of CYP3A inhibitors/inducers on esaxerenone pharmacokinetics in healthy subjects and subjects with hepatic impairment.

PURPOSE: Esaxerenone is a novel, oral, nonsteroidal treatment for hypertension. Physiologically based pharmacokinetic (PBPK) modelling was performed to predict the drug-drug interaction (DDI) effect of cytochrome P450 (CYP)3A modulators on esaxerenone pharmacokinetics in healthy subjects and subjects with hepatic impairment. METHODS: In our PBPK model, the fraction of esaxerenone metabolised by CYP3A was estimated from mass-balance data and verified and optimised by clinical DDI study results with strong CYP3A modulators. The model was also verified by the observed pharmacokinetics after multiple oral dosing and by the effect of hepatic impairment on esaxerenone pharmacokinetics. The model was applied to predict the DDI effects on esaxerenone pharmacokinetics with untested CYP3A modulators in healthy subjects and with strong CYP3A modulators in subjects with hepatic impairment. RESULTS: The PBPK model well described esaxerenone pharmacokinetics after multiple oral dosing. The predicted fold changes in esaxerenone plasma exposure after coadministration with strong CYP3A modulators were comparable with the observed data (1.53-fold with itraconazole and 0.31-fold with rifampicin). Predicted DDIs with untested moderate CYP3A modulators were less than the observed DDI with strong CYP3A modulators. The PBPK model also described the effect of hepatic impairment on esaxerenone plasma exposure. The predicted DDI results with strong CYP3A modulators in subjects with hepatic impairment indicate that, for concomitant use of CYP3A modulators, caution is advised for subjects with hepatic impairment, as is for healthy subjects. CONCLUSION: The PBPK model developed predicted esaxerenone pharmacokinetics and DDIs and informed concurrent use of esaxerenone with CYP3A modulators.

Effects of Repeated Oral Administration of Esaxerenone on the Pharmacokinetics of Midazolam in Healthy Japanese Males.

BACKGROUND AND OBJECTIVE: Esaxerenone showed the potential to inhibit and induce activity against cytochrome P450 (CYP) 3A in in vitro studies. We investigated whether repeated administration of 5 mg/day esaxerenone for 14 days influences the pharmacokinetics of midazolam, a sensitive CYP3A substrate, in healthy Japanese males. METHODS: This single-centre, open-label, single-sequence study had two administration periods: period 1: single oral dose of 2 mg midazolam (day 0); period 2: repeated oral doses of 5 mg/day esaxerenone for 14 days, with a single oral dose of 2 mg midazolam on day 14. Full pharmacokinetic profiles of midazolam and 1-hydroxymidazolam on days 0 and 14 and safety data were obtained. Primary pharmacokinetic endpoints for midazolam were area under the plasma concentration-time curve (AUC) from zero to time of the last measurable concentration (AUClast), AUC from zero to infinity (AUCinf), and peak plasma concentration (Cmax). RESULTS: The study included 28 male subjects. One subject was withdrawn because of a mild adverse event (increased hepatic enzyme levels) that resolved without intervention. Repeated administration of esaxerenone increased midazolam AUClast, AUCinf, and Cmax by about 1.2-fold (1.201, 1.201, and 1.224, respectively) compared with administration of midazolam alone. However, repeated administration of esaxerenone did not affect the elimination half-life of midazolam (2.86 versus 2.63 h with and without esaxerenone). There were no safety concerns associated with concomitant administration of esaxerenone and midazolam. CONCLUSIONS: Esaxerenone 5 mg/day had no clinically significant effect on midazolam pharmacokinetics and was not associated with any safety issues. Esaxerenone can be concomitantly administered with drugs of CYP3A substrates without dose adjustments. CLINICAL TRIAL REGISTRATION: JapiCTI-152832.

[Pharmacological profile, clinical efficacy, and safety of esaxerenone (Minnebro® tablets 1.25†mg, 2.5†mg, 5†mg)].

Esaxerenone is a novel non-steroidal mineralocorticoid receptor antagonisit (MR blocker), whose unique binding to the MR-ligand domain yields a stronger MR antagonistic effect and higher selectivity than existing MR antagonisits. Esaxerenone was approved for the treatment of hypertension in Japan in January 2019. Esaxerenone suppresses the reduction of urinary Na+/K+ ratio in adrenalectomized rats and blood pressure increase, proteinuria, and renal tissue lesions in salt-sensitive hypertensive rats-all in a dose-dependent manner. Esaxerenone is rapidly absorbed and reaches intracellular targets because of its high membrane permeability, exhibits high bioavailability with small interindividual exposure variation, and is metabolized via several pathways (e.g., oxidation, glucuronidation, and hydrolysis), which is associated with low drug-drug interaction risk. As esaxerenone is slightly excreted into urine, its exposure is similar between elderly and non-elderly patients, and between patients with normal and moderately deteriorated renal function. Given its 19-hour half-life, once-daily administration would have a sustainable antihypertensive effect. The ESAX-HTN phase 3 study demonstrated the non-inferiority of esaxerenone's antihypertensive effect versus that of eplerenone in essential hypertension. Another study showed a stable antihypertensive effect for 52 weeks as monotherapy or combination therapy. In hypertensive patients with moderate impairment or both type 2 diabetes and albuminuria treated with a renin-angiotensin system inhibitor, esaxerenone elicited a stable antihypertensive effect and manageable hyperkalemia incidence with titration from a low dose and monitoring including serum potassium. Thus, with careful monitoring of serum potassium, esaxerenone can be administered to patients with moderate renal impairment or both diabetes and albuminuria.

Fibroblast growth factor receptor modulators employing diamines with reduced phospholipidosis-inducing potential.

SUN13837 (1), a fibroblast growth factor receptor modulator, has been an attractive candidate for treating neurodegenerative diseases. However, one of its metabolites, N-benzyl-4-(methylamino)piperidine (BMP), turned out to possess phospholipidosis-inducing potential (PLIP) in vitro. To obtain SUN13837 analogs with reduced phospholipidosis risk, we replaced BMP with other diamines possessing low PLIP. Our effort led to the discovery of compound 6 with increased efficacy. Further structural modifications to reduce hydrogen bond donors afforded 17 with improved brain exposure. Oral administration of 17 at 1 mg/kg once daily for 10 days showed enhanced recovery of coordinated movement in a rat acute stroke model, suggesting that it is a promising follow-up compound for 1 with reduced risk of phospholipidosis.

Identification and Characterization of a New Carboxylesterase 2 Isozyme, mfCES2C, in the Small Intestine of Cynomolgus Monkeys.

In contrast to a single human carboxylesterase 2 (CES2) isozyme (hCE2), three CES2 genes have been identified in cynomolgus monkeys: mfCES2A, mfCES2B, and mfCES2C . Although mfCES2A protein is expressed in several organs, mfCES2B is a pseudogene and the phenotype of the mfCES2C gene has not yet been clarified in tissues. In previous studies, we detected an unidentified esterase in the region of CES2 mobility upon nondenaturing PAGE analysis of monkey intestinal microsomes, which showed immunoreactivity for anti-mfCES2A antibody. The aim of the present study was to identify this unidentified esterase from monkey small intestine. The esterase was separated on nondenaturing PAGE gel and digested in-gel with trypsin. The amino acid sequences of fragmented peptides were analyzed by tandem mass spectrometry. The unidentified esterase was shown to be identical to mfCES2C (XP_015298642.1, predicted from the genome sequence data). mfCES2C consists of 559 amino acid residues and shows approximately 90% homology with mfCES2A (561 amino acid residues). In contrast to the ubiquitous expression of mfCES2A, mfCES2C is only expressed in the small intestine, kidney, and skin. The hydrolytic properties of recombinant mfCES2C, expressed in HEK293 cells, with respect to p-nitrophenyl derivatives, 4-methylumbelliferyl acetate, and irinotecan were similar to those of recombinant mfCES2A. However, mfCES2C showed a hydrolase activity for O-n-valeryl propranolol higher than mfCES2A. It is concluded that the previously unidentified monkey intestinal CES2 is mfCES2C, which shows different hydrolytic properties to mfCES2A, depending on the substrate. SIGNIFICANCE STATEMENT: In the present research, we determined that mfCES2C, a novel monkey CES2 isozyme, is expressed in the small intestine and kidney of the cynomolgus monkey. Interestingly, mfCES2C showed a relatively wide substrate specificity for ester-containing compounds. These findings may, in early stages of drug development, support the use of in vitro-to-in vivo extrapolation for the intestinal hydrolysis of ester drugs in the cynomolgus monkey.

Discovery of 1,2,3-triazole-based fibroblast growth factor receptor modulators.

To avoid production of a phospholipidosis-inducing metabolite, we replaced the amide structure of SUN13837 (1) with a 1,2,3-triazole. The resulting 1,2,3-triazole analog of 1 (compound 2) displayed greater neuroprotective activity than 1. Structural modification of 2 yielded compound 10, which showed improved neuroprotective activity and negligible mechanism-based inactivation against CYP3A4. In addition, installation of a methyl group at the 5-position of 1,2,3-triazole of 10 significantly boosted the neuroprotective activity. These 1,2,3-triazole derivatives displayed reduced phospholipidosis risk, sufficient systemic exposure, and high central nervous system penetration, and therefore may be potentially useful agents for the treatment of neurodegenerative diseases.

Analysis of carboxylesterase 2 transcript variants in cynomolgus macaque liver.

Carboxylesterase (CES) is important for the detoxification of a wide range of drugs and xenobiotics. In this study, the hepatic level of CES2 mRNA was examined in cynomolgus macaques used widely in preclinical studies for drug metabolism. Three CES2 mRNAs were present in cynomolgus macaque liver. The mRNA level was highest for cynomolgus CES2A (formerly CES2v3), much lower for cynomolgus CES2B (formerly CES2v1) and extremely low for cynomolgus CES2C (formerly CES2v2). Most various transcript variants produced from cynomolgus CES2B gene did not contain a complete coding region. Thus, CES2A is the major CES2 enzyme in cynomolgus liver. A new transcript variant of CES2A, CES2Av2, was identified. CES2Av2 contained exon 3 region different from wild-type (CES2Av1). In cynomolgus macaques expressing only CES2Av2 transcript, CES2A contained the sequence of CES2B in exon 3 and vicinity, probably due to gene conversion. On genotyping, this CES2Av2 allele was prevalent in Indochinese cynomolgus macaques, but not in Indonesian cynomolgus or rhesus macaques. CES2Av2 recombinant protein showed similar activity to CES2Av1 protein for several substrates. It is concluded that CES2A is the major cynomolgus hepatic CES2, and new transcript variant, CES2Av2, has similar functions to CES2Av1.

Differences in Intestinal Hydrolytic Activities between Cynomolgus Monkeys and Humans: Evaluation of Substrate Specificities Using Recombinant Carboxylesterase 2 Isozymes.

Cynomolgus monkeys, used as an animal model to predict human pharmacokinetics, occasionally show different oral absorption patterns to humans due to differences in their intestinal metabolism. In this study, we investigated the differences between intestinal hydrolytic activities in cynomolgus monkeys and humans, in particular the catalyzing activities of their carboxylesterase 2 (CES2) isozymes. For this purpose we used both human and monkey microsomes and recombinant enzymes derived from a cell culture system. Monkey intestinal microsomes showed lower hydrolytic activity than human microsomes for several substrates. Interestingly, in contrast to human intestinal hydrolysis, which is not enantioselective, monkey intestine showed preferential R-form hydrolysis of propranolol derivatives. Recombinant CES2 isozymes from both species, mfCES2v3 from monkeys and human hCE2, showed similar metabolic properties to their intestinal microsomes when expressed in HEK293 cells. Recombinant hCE2 and mfCES2v3 showed similar Km values for both enantiomers of all propranolol derivatives tested. However, recombinant mfCES2v3 showed extreme R-enantioselective hydrolysis, and both hCE2 and mfCES2v3 showed lower activity for O-3-methyl-n-butyryl propranolol than for O-n-valeryl and O-2-methyl-n-butyryl propranolol. This lower hydrolytic activity was characterized by lower Vmax values. Docking simulations of the protein-ligand complex demonstrated that the enantioselectivity of mfCES2v3 for propranolol derivatives was possibly caused by the orientation of its active site being deformed by an amino acid change of Leu107 to Gln107 and the insertion of Met309, compared with hCE2. In addition, molecular dynamics simulation indicated the possibility that the interatomic distance between the catalytic triad and the substrate was elongated by a 3-positioned methyl in the propranolol derivatives. Overall, these findings will help us to understand the differences in intestinal hydrolytic activities between cynomolgus monkeys and humans.

Orally active ghrelin receptor inverse agonists and their actions on a rat obesity model.

A series of 2-alkylamino nicotinamide analogs was prepared as orally active ghrelin receptor (ghrelinR) inverse agonists. Starting from compound 1, oral bioavailability was improved by modifying metabolically unstable sites and reducing molecular weight. Brain-permeable compound 33 and compound 24 with low brain permeability were tested in rat models of obesity; 30 mg/kg of compound 33 suppressed weight gain. PK/PD analysis revealed that the anti-obesity effect of ghrelinR inverse agonists depends on their brain concentrations.

SUN11602-induced hyperexpression of calbindin D-28k is pivotal for the survival of hippocampal neurons under neurotoxic conditions.

Basic fibroblast growth factor (FGF-2/bFGF) possesses neuroprotective activity and promotes cell proliferation. In this study, the novel synthetic compound 4-({4-[[(4-amino-2,3,5,6-tetramethylanilino)acetyl](methyl)amino]-1-piperidinyl}methyl)benzamide (SUN11602) exhibited neuroprotective activities similar to those of FGF-2 without promoting cell proliferation. In primary cultures of hippocampal neurons, stimulation with SUN11602 or FGF-2 increased calbindin D-28k (CalB) gene expression and prevented glutamate-induced neuronal death. These effects were abolished by pretreatment with PD166866 (FGF receptor 1 [FGFR1] tyrosine kinase-specific inhibitor). This indicated that FGFR1 activation and increased CalB expression were involved in SUN11602-mediated neuroprotection. However, receptor-binding assays revealed that unlike FGF-2, SUN11602 did not alter the binding of (125)I-labeled FGF-2 to FGFR1. To investigate the possible proliferative activity of SUN11602, we utilized BHK21 and SKN cells expressing endogenous FGFR1. FGF-2 promoted cell proliferation whereas SUN11602 did not. In in vivo studies, wild-type (WT) and CalB-deficient (CalB(-/-)) mice were injected with aggregated Aß1-40 and ibotenate (NMDA receptor agonist) to severely damage the hippocampal tissue. Treatment with SUN11602 (orally) or FGF-2 (intraparenchymally) at the midpoint of Aß1-40 and ibotenate injections prevented the hippocampal damage in WT mice, however this effect was abolished in CalB(-/-) mice. Thus, SUN11602 exerted protective effects on hippocampal neurons through activation of FGFR1 and increased CalB expression. Moreover, the neuroprotective effects of SUN11602 depended upon the various biological activities of FGF-2.

In vitro and in vivo metabolism of a novel chymase inhibitor, SUN13834, and the predictability of human metabolism using mice with humanized liver.

1. A novel oral chymase inhibitor, SUN13834, is under clinical development for the treatment of atopic dermatitis (AD). In this study, in vitro and in vivo metabolic profiles of SUN13834 were compared between severe combined immunodeficiency (SCID) mice, chimeric mice with humanized liver and humans. 2. In in vitro experiments using liver microsomes, predominant metabolites of SUN13834 were glucuronide (MG-1) in SCID mice and hydroxylated metabolite (M-3) in chimeric mice and humans. 3. After a single oral dose of [(14)C]SUN13834 to SCID and chimeric mice, glucuronidation was the major metabolic pathway in SCID mice, while the parent compound, ring opening form (M-5), O-demethylated form of M-5 (M-6) and glucuronidation of M-6 (M-6G) were detected at higher levels in chimeric mice compared to SCID mice. 4. When AD patients were orally treated using SUN13834 for 28 days, the parent compound had the highest concentration in plasma, and M-6, M-6G, M-5 and MG-1 were identified as major metabolites. 5. This is the first report of SUN13834 metabolic information in human. In addition, based on similarities in metabolic profiles between chimeric mice and humans, it was concluded that chimeric mice are useful for predicting SUN13834 metabolism in humans during early stages of drug development.

Evaluation of ovotoxicity induced by 7, 12-dimethylbenz[a]anthracene and its 3,4-diol metabolite utilizing a rat in vitro ovarian culture system.

The polycyclic aromatic hydrocarbon 7, 12-dimethylbenz[a]anthracene, (DMBA), targets and destroys all follicle types in rat and mouse ovaries. DMBA requires bioactivation to DMBA-3,4-diol-1,2-epoxide for ovotoxicity via formation of the intermediate, DMBA-3,4-diol (catalyzed by microsomal epoxide hydrolase; mEH). mEH was shown to be involved in DMBA bioactivation for ovotoxicity induction in B6C3F(1) mouse ovaries. The current study compared DMBA and DMBA-3,4-diol mediated ovotoxicity, and investigated mEH involvement in DMBA-3,4-diol bioactivation in Fischer 344 (F344) rat ovary. F344 postnatal day (PND) 4 rat ovaries were cultured in vehicle control or media containing 1) DMBA or DMBA-3,4-diol (12.5 nM - 1 muM; 15 days); 2) DMBA (1 muM; 6 h - 15 days); and 3) DMBA (1 muM) or DMBA-3,4-diol (75 nM)+/-the mEH activity inhibitor cyclohexene oxide (CHO; 2 mM; 4 days). Ovaries were histologically evaluated and mEH mRNA and protein were measured by reverse transcriptase PCR or Western blotting, respectively. Ovotoxicity following 15 days of culture occurred (P<0.05) at lower concentrations of DMBA-3,4-diol (12.5 nM - primordial; 75 nM - primary) than DMBA (75 nM - primordial; 375 nM - primary). The temporal pattern of mEH expression following DMBA exposure showed mRNA up-regulation (P<0.05) on day 2, with increased protein (P<0.05) on day 4, the earliest time of observed follicle loss (P<0.05). mEH inhibition prevented DMBA-induced, but not DMBA-3,4-diol-induced ovotoxicity. These results demonstrate a conserved response in mice and rats for ovarian mEH involvement in DMBA bioactivation to its ovotoxic, 3,4-diol-1,2-epoxide form.