Phase 1 Study to Investigate the Safety, Tolerability, and Pharmacokinetics of EPI-589 in Healthy Participants.

EPI-589 attenuates oxidative stress due to the radical scavenging activity of the reduced form and affects mitochondrial energy metabolism as a substrate of quinone-oxidoreductases. Given the effects of EPI-589 on oxidative stress and mitochondrial dysfunction, EPI-589 shows promise as a potential therapy for patients with amyotrophic lateral sclerosis. This phase 1 study evaluated the safety, tolerability, and pharmacokinetic profiles of EPI-589. Sixty-eight healthy participants were randomly assigned to EPI-589 or placebo. All adverse events were mild or moderate in severity, and no severe adverse events were reported. After single-dose administration under fasting conditions, time to maximum plasma concentration (tmax ) occurred 0.25 to 1.00 hour after administration. Both peak plasma concentration (Cmax ) and area under the plasma concentration-time curve (AUC) were approximately linear with increases in single doses over a dose range of 250-1000 mg. Under fed conditions, the Cmax decreased to 62.6% of the Cmax under fasting conditions, the AUC was slightly increased, and the tmax was delayed by 1 hour. When EPI-589 was administered daily on days 1 and 7 with twice-daily dosing on days 2 through 6, the plasma trough concentration appeared to reach steady state by day 3. At both doses studied (500 mg twice daily and 750 mg twice daily), Cmax, tmax , and AUC were generally comparable between day 1 and day 7 and between the Japanese and White participants. EPI-589 was well tolerated as a single daily dose up to 1000 mg and as twice-daily doses up to 750 mg, with a linear pharmacokinetic profile.

Quantitative time-lapse imaging-based analysis of drug-drug interaction mediated by hepatobiliary transporter, multidrug resistance-associated protein 2, in sandwich-cultured rat hepatocytes.

There is increasing interest in developing efficient screening platforms to predict drug-induced liver injury. Therefore, we explored a microscope-based analysis to quantitatively evaluate interaction of drugs with multidrug resistance-associated protein 2 (MRP2), essential for hepatic excretion of drugs in sandwich-cultured rat hepatocytes (SCRHs), using 5 (and 6)-carboxy-2',7'-dichlorofluorescein (CDF) diacetate, which is intracellularly hydrolyzed to the fluorescent substrate CDF. Drug-MRP2 interactions were evaluated by measuring the fluorescence change in bile canaliculi in SCRHs in the presence or absence of MRP2 inhibitors using quantitative time-lapse imaging (QTLI) analysis. Fluorescence was negligible in SCHs from rat (r) Mrp2-deficient Eisai hyperbilirubinemic rat, suggesting that Mrp2 is primarily responsible for CDF accumulation. According to QTLI, rifampicin, cyclosporine, and 3-[[3-[2-(7-chloroquinolin-2-yl)vinyl]phenyl]-(2-dimethylcarbamoylethylsulfanyl)methylsulfanyl] propionic acid (MK-571) attenuated CDF accumulation in a concentration-dependent manner, with IC50 values (IC50, QTLI)) of 3.02, 1.63, and 2.87 µM, respectively. The ratios of IC50 values obtained from the biliary excretion index over the IC(50, QTLI) were 1.34, 1.94, and 1.94, but ratios over IC50 values in CDF uptake by Mrp2-expressing membrane vesicles varied more: 6.69, 3.07, and 2.43 for rifampicin, cyclosporine, and MK-571, respectively. When the IC(50, QTLI) of rifampicin was corrected for the hepatocyte/medium distribution ratio, the relative ratio of IC(50, VES)/IC(50, QTLI) was reduced to 2.25 from 6.69 (20.2/3.02) and was close to the ratio for MK-571 (2.43, 6.96/2.87), which is thought to cross the plasma membrane by passive diffusion. Our results indicate that QTLI is a suitable method to evaluate drug-MRP2 interaction at the bile canalicular membrane, when the hepatocyte/medium distribution ratio in SCRHs is taken into account.

Pharmacokinetics, safety and metabolite profiling of minesapride, a novel 5-HT4 receptor partial agonist, in healthy elderly and young subjects.

Minesapride is a novel 5-hydroxytryptamine 4 (5-HT4) receptor partial agonist that is expected to show efficacy in patients with irritable bowel syndrome with predominant constipation and functional constipation. An open-label study was conducted to evaluate pharmacokinetics (PK) and safety of minesapride. Japanese subjects, 12 elderly and 12 young, received a single oral dose of minesapride 40 mg/day in the fasted state. Metabolite profiles were also investigated in this clinical study and in an in vitro study using cryopreserved hepatocytes. Clinical results showed that minesapride was rapidly absorbed (Cmax: 2302.1 ng/mL in the elderly group, 2117.5 ng/mL in the young group), and the plasma concentration then decreased with half-life of approximately 7 h. There were no notable PK differences between elderly and young groups. No serious adverse events (AEs) were observed. The only AE that occurred in 2 or more subjects was diarrhea. Metabolite profiles in plasma and urine were similar between elderly and young groups. No major metabolites exceeded 10% of unchanged minesapride, and results of the in vitro study suggested that there were no human-specific metabolites. From the viewpoints of PK and metabolite profiling, no dose adjustment of minesapride is warranted in elderly population without renal or hepatic impairment.

Hepatic uptake of gamma-butyrobetaine, a precursor of carnitine biosynthesis, in rats.

Gamma-butyrobetaine (GBB) is a precursor in the biosynthesis of carnitine, which plays an important role in the beta-oxidation of fatty acids, and is converted to carnitine by gamma-butyrobetaine dioxygenase (BBD) predominantly in liver. We investigated the molecular mechanism of hepatic uptake of GBB in rat hepatocytes. Cellular localization of rat Octn2 (rOctn2:Slc22A5) was studied by Western blot analysis. Uptake of deuterated GBB (d(3)-GBB) was examined in HEK293 cells expressing rOctn2 (HEK293/rOctn2) and freshly isolated rat hepatocytes. d(3)-GBB was quantified by use of liquid chromatography-tandem mass spectrometry. Western blot analysis demonstrated an expression of OCTN2 protein in hepatic basolateral membrane but not in bile canalicular membrane fraction. Furthermore, we found that d(3)-GBB was taken up by rOctn2 in an Na(+)-dependent manner with K(m) value of 13 microM. The apparent K(m) value for d(3)-GBB transport in freshly isolated rat hepatocytes was 9 microM. d(3)-GBB uptake by the rat hepatocytes was inhibited by gamma-aminobutyric acid (GABA) to 30% of the control, whereas it was inhibited by carnitine to 62% of the control, even at 500 microM. Furthermore, d(3)-GBB uptake by rat hepatocytes was decreased by 45% with rat Gat2 (Slc6A13, a major liver GABA transporter) silenced by the microRNA method. Accordingly, the present study clearly demonstrates that GBB is taken up by hepatocytes for carnitine biosynthesis not only via Octn2 but also via the GABA transporter, possibly Gat2.

Concentration-dependent effect of naringin on intestinal absorption of beta(1)-adrenoceptor antagonist talinolol mediated by p-glycoprotein and organic anion transporting polypeptide (Oatp).

PURPOSE: The purpose of this study is to clarify the impact of P-gp and Oatp on intestinal absorption of the beta(1)-adrenoceptor antagonist talinolol. METHODS: P-gp-mediated transport was measured in LLC-PK1/MDR1 cells. Oatp-mediated uptake was evaluated with Xenopus oocytes expressing Oatp1a5. Rat intestinal permeability was measured by the in situ closed loop method. In vivo absorption was pharmacokinetically assessed by measuring plasma concentration after oral administration in rats. RESULTS: In LLC-PK1/MDR1 cells, the permeability of talinolol was markedly higher in the secretory direction than in the absorptive one. The uptake of talinolol by Xenopus oocytes expressing Oatp1a5 was significantly increased compared with that by water-injected oocytes. Naringin inhibited talinolol uptake by Oatp1a5 (IC (50) = 12.7 microM). The reported IC (50) value of naringin for P-gp-mediated transport of talinolol is approximately 2,000 microM. Rat intestinal permeability of talinolol was significantly decreased in the presence of 200 microM naringin, but was significantly increased by 2,000 microM naringin. Similar results were obtained in in vivo absorption studies in rats. CONCLUSION: The absorption behavior of talinolol can be explained by the involvement of both P-gp and Oatp, based on characterization of talinolol transport by Oatp1a5 and P-gp, and the effects of naringin.