Elucidation of clearance mechanism of TP0463518, a novel hypoxia-inducible factor prolyl hydroxylase inhibitor: does a species difference in excretion routes exist between humans and animals?

1. TP0463518, a novel hypoxia-inducible factor prolyl hydroxylase inhibitor, is reportedly excreted predominantly through urinary excretion in an unchanged form in humans, with partial biliary excretion also possible. However, the clearance mechanisms remain unclear. The aim of this study was to investigate the clearance mechanisms in humans and to assess species differences in the excretion routes.2. TP0463518 was not metabolised in rat, dog, or human hepatocytes. TP0463518 is a substrate for human BCRP, OATP1B1, OATP1B3, and OAT3, suggesting that renal uptake by OAT3 is probably the predominant clearance route, with hepatic uptake by OATP1B1 and OATP1B3 contributing partially to clearance in humans.3. A species difference in excretion routes was observed. The unchanged urinary excretion rates in humans, male rats, female rats, dogs, and monkeys were 80.7%, 0.1%, 40.9%, 15.2%, and 72.6%, respectively. Urinary excretion was predominant in humans and monkeys, while only biliary excretion was observed in male rats. Uptake studies using hepatocytes showed that the hepatic uptake clearance in rats was 13.6-fold higher than that in humans. Therefore, not only reabsorption via renal tubules, but also hepatic uptake seems to be involved in the species differences in excretion routes between rats and humans.

Drug-drug interaction potential and clinical pharmacokinetics of enerisant, a novel potent and selective histamine H3 receptor antagonist.

We evaluated the in vitro drug-drug interaction (DDI) potential of enerisant (TS-091), a histamine H3 receptor antagonist/inverse agonist, mediated by cytochrome P450 (CYP) and transporters, as well as the pharmacokinetics of enerisant in healthy male subjects.Enerisant did not inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, or CYP3A4 and did not induce CYP1A2, CYP2B6, or CYP3A4. Enerisant inhibited organic cation transporter 2, multidrug and toxin extrusion protein (MATE) 1, and MATE2-K, but not P-glycoprotein (P-gp), breast cancer resistance protein, organic anion transporting polypeptide (OATP) 1B1, OATP1B3, organic anion transporter (OAT) 1, or OAT3. Enerisant was a substrate for P-gp, but not for eight other transporters.In healthy male subjects, enerisant was rapidly absorbed after oral administration, and the plasma concentration increased dose-dependently. The urinary excretion of enerisant within 48 h after administration was 64.5% to 89.9% of the dose, indicating that most of the absorbed enerisant was excreted in the urine without being metabolized.Based on the plasma concentrations at the estimated clinical dose, enerisant is unlikely to cause CYP-mediated, clinically relevant DDI. Although the possibility of transporter-mediated, clinically relevant DDI cannot be ruled out, there is little or no risk of side effects.

In vitro evaluation of potential drug interactions mediated by cytochrome P450 and transporters for luseogliflozin, an SGLT2 inhibitor.

1. We evaluated potential in vitro drug interactions of luseogliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, mediated by CYP inhibition, CYP induction and drug transporters using human liver microsomes, primary hepatocytes and recombinant cells-expressing efflux or uptake transporters, respectively. 2. Human CYP inhibition studies indicated that luseogliflozin was a weak inhibitor for CYP2C19 with an IC50 value of 58.3 µM, whereas it was not an inhibitor of the other eight major isoforms that were tested. The exposure of primary hepatocytes to luseogliflozin for 72 hrs weakly induced CYP3A4 at a concentration of 10 µM, whereas it did not induce CYP1A2 or CYP2B6 at concentrations of 0.1-10 µM. 3. An in vitro transport study suggested that luseogliflozin is a substrate for human P-glycoprotein (P-gp), but not for breast cancer resistance protein (BCRP), organic anion transporting polypeptide (OATP) 1B1 and OATP1B3, organic anion transporter (OAT) 1 and OAT3, or organic cation transporter (OCT) 2. Luseogliflozin weakly inhibited OATP1B3 with an IC50 value of 93.1 µM, but those for other transporters are greater than 100 µM. 4. Based on the therapeutic plasma concentration of the drug, clinically relevant drug interactions are unlikely to occur between luseogliflozin and coadministered drugs mediated by CYPs and/or transporters.

[A long-term survivor after relapsed acute myeloblastic leukemia with anthracycline dilated cardiomyopathy].

We watched and analyzed patient cardiac functions especially with a "Phased tracking method" to detect rapid motion of the heart. The patient suffered from congestive heart failure while depending on anthracycline cumulative doses, but now has been living more than 10 years after relapsed acute myeloblastic leukemia. To avoid congestive heart failure with increasing highly tumoricidal anthracycline doses, cardiac function should be monitored closely in connection with treatment schedules and proposed accurate therapeutic index.

Formation of a disulfide protein conjugate of the SH-group-containing metabolite (M-I) of esonarimod (KE-298) and its elimination in rats.

The reactivity of the thiol moiety of the active main metabolite (M-I) of esonarimod (KE-298), a novel anti-rheumatic agent, was investigated in rats. After repeated oral administration of 14C-KE-298, the radioactivity decreased rapidly and no tendency towards accumulation was found, in marked contrast to other common SH-group-containing drugs. At 30 min after intravenous administration of 14C-M-I to rats, the concentration of the 14C-M-I plasma protein conjugate in plasma was extremely low at 0.143 nmol mL(-1) (0.66% of total plasma radioactivity). The 14C-M-I plasma protein conjugate that formed in rat plasma was mixed disulfide with plasma protein. After intravenous administration of synthetic 14C-M-I plasma protein conjugate to rats, the radioactivity in plasma decreased rapidly, with the terminal half-life at 6.90 h. In-vitro, the 14C-M-I plasma protein conjugate was readily dissociated by the endogenous thiol compounds, cysteine and glutathione. These results suggest that the reactivity of the thiol moiety of M-I is extremely low. Furthermore, the 14C-M-I plasma protein conjugate decreased rapidly in-vivo, which would be related to interaction with endogenous thiol compounds. These properties of M-I are principally responsible for the zero accumulation in rat tissues. KE-298 could therefore be expected to have reduced adverse effects compared with other SH-group-containing anti-rheumatic drugs.