Improvement of absorbability, osteoconductivity, and strength of a ß-tricalcium phosphate spacer for opening wedge high tibial osteotomy: clinical evaluations with 106 patients.

BACKGROUND: An ideal synthetic spacer for medial opening wedge high tibial osteotomy (MOWHTO) has not yet been developed. The authors have developed a new ß-tricalcium phosphate (ß-TCP) spacer with 60% porosity (N-CP60) by modifying the micro- and macro-pore structures of a conventional ß-TCP spacer (CP60) that is widely used in clinical practice. The purpose of this study was to compare the absorbability, osteoconductivity, and in vivo strength of the N-CP60 spacer with those of the CP60 spacer, when used in MOWHTO. METHODS: First, the porosity, diameter distribution of macro- and micropores, and compressive strength of each ß-TCP block were examined using methodology of biomaterial science. Secondly, a clinical study was performed using a total of 106 patients (106 knees) with MOWHTO, who were followed up for 18 months after surgery. In these knees, the N-CP60 and CP-60 spacers were implanted into 49 tibias and 57 tibias, respectively. The absorbability and osteoconductivity were radiologically evaluated by measuring the area of the implanted spacer remaining unabsorbed and assessing with the Hemert's score, respectively. The incidence of cracking in the implanted spacers was determined using computed radiography. Statistical comparisons were made with non-parametric tests. The significance level was set at p = 0.05. RESULTS: The N-CP60 and CP60 blocks had almost the same porosity (mean, 61.0% and 58.7%, respectively). The diameter of macropores was significantly larger (p < 0.0001) in the N-CP60 block than in the CP60 block, while the diameter of micropores was significantly smaller (p = 0.019) in the N-CP60 block. The ultimate strength of the N-CP60 block (median, 36.8 MPa) was significantly greater (p < 0.01) than that of the CP60 block (31.6 MPa). As for the clinical evaluations, the absorption rate of the N-CP60 spacer at 18 months after implantation (mean, 48.0%) was significantly greater (p < 0.001) than that of the CP60 spacer (29.0%). The osteoconductivity of the N-CP60 spacer was slightly but significantly higher (p = 0.0408) than that of the CP60 spacer only in zone 1. The incidence of in vivo cracking of the posteriorly located N-CP60 spacer at one month (mean, 75.5%) was significantly lower (p = 0.0035) than that of the CP60 spacer (91.2%). CONCLUSIONS: The absorbability, osteoconductivity, and compressive strength of the new N-CP60 spacer were significantly improved by modifying the macro- and micro-pore structures, compared with the conventional CP60 spacer. The N-CP60 spacer is more clinically useful than the CP60 spacer. TRIAL REGISTRATION NUMBER: H29-0002.

Preclinical Metabolism and Disposition of TP0473292, a Novel Oral Prodrug of the Potent Metabotropic Glutamate 2/3 Receptor Antagonist TP0178894 for the Treatment of Depression.

TP0473292 is an adamantane carboxylic acid (ACA) ester prodrug for enhancing the oral bioavailability of the hydrophilic glutamate analog TP0178894, a novel metabotropic glutamate 2 and 3 receptor antagonist, and being developed as an antidepressant. TP0473292 showed high membrane permeability and rapid hydrolysis to TP0178894 in rat, monkey, and human liver S9 fractions, with a conversion rate of such that complete conversion by first-pass metabolism was expected. TP0473292 was also hydrolyzed in the intestinal, renal, and lung S9 fractions, coinciding with the result that TP0473292 was activated by carboxylesterase (CES) 1 and more efficiently by CES2. Despite the rapid hydrolysis of TP0473292 in the intestinal S9 fraction, TP0473292 achieved good oral bioavailability of poorly permeable TP0178894 (approximately 60%) in rats and monkeys, with no TP0473292 detected in the plasma, revealing that rapid hydrolysis in the intestine is not necessarily a disadvantage. We also confirmed the penetration of TP0178894 into the cerebrospinal fluid and its unmetabolized excretion in urine. The ester promoiety, ACA, was metabolized to chemically stable acyl glucuronide and excreted in urine in rats and monkeys, suggesting a low risk of idiosyncratic drug toxicity. TP0473292 and its metabolites did not show a drug-drug interaction potential via cytochrome P450 in humans. These results suggested that TP0473292 functions as an ideal oral prodrug in humans; this was later confirmed to be true in phase 1 clinical trials. Furthermore, ACA was firstly confirmed to be a useful promoiety for hydrophilic drugs to enhance their oral bioavailability. SIGNIFICANCE STATEMENT: Hydrolysis in the intestine reportedly has negative effects on the oral bioavailability of hydrophilic active metabolites of ester prodrugs. This study reports the preclinical pharmacokinetics of a hydrophilic metabotropic glutamate 2/3 receptor antagonist, TP0178894, and its ester prodrug TP0473292, which was found to act as an oral prodrug despite being activated predominantly in the intestine. Furthermore, this study firstly reports that adamantane carboxylic acid is useful as the ester promoiety of a prodrug for increasing lipophilicity and oral bioavailability.

Bottom-up physiologically based pharmacokinetic modelling for predicting the human pharmacokinetic profiles of the ester prodrug MGS0274 and its active metabolite MGS0008, a metabotropic glutamate 2/3 receptor agonist.

For ester prodrugs that are used to improve the gastrointestinal absorption of highly hydrophilic, pharmacologically active substances, it is challenging to predict the human pharmacokinetics (PK) of the prodrugs and their parent compounds using only preclinical data.This research was aimed at constructing a PBPK model for predicting the human PK of the ester prodrug MGS0274 and its parent compound MGS0008 after a single oral administration of MGS0274 besylate.First, we identified carboxylesterase 1 (CES1) as the major enzyme involved in the hydrolysis of MGS0274. Second, we constructed a new compartment model to estimate the passive diffusion clearance (CLpd) of MGS0008, a critical parameter for predicting the PK of highly hydrophilic compounds, based on in vivo monkey PK data. Finally, we constructed a permeability-limited liver PBPK model incorporating the CLpd assumed to be the same in humans.We confirmed that our method reliably predicted the human PK and that the estimated CLpd was comparable to that calculated retrospectively using the PBPK model, suggesting that the methodology for estimating the CLpd was valid.Our proposed methodology is expected to be helpful for human PK prediction of ester prodrugs hydrolysed by CES1 and their hydrophilic parent compounds even during the preclinical phase.

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.

Downregulation of CYP1A2, CYP2B6, and CYP3A4 in Human Hepatocytes by Prolyl Hydroxylase Domain 2 Inhibitors via Hypoxia-Inducible Factor-α Stabilization.

Hypoxia-inducible factor (HIF) is associated with the expression of CYP, but the underlying mechanism remains uncertain. In this study, we investigated the effect of HIF-α stabilization caused by novel prolyl hydroxylase domain (PHD) 2 inhibitors, which are HIF-α stabilizers that mimic hypoxia, on the expressions of CYP1A2, CYP2B6, and CYP3A4 in human hepatocytes. An mRNA expression analysis of human hepatocytes treated with PHD2 inhibitors for 72 hours showed the downregulation of genes encoding CYP1A2, CYP2B6, and CYP3A4. The mRNA repressions were accompanied with an increase in erythropoietin protein, a marker of HIF-α stabilization, indicating that HIF-α stabilization was involved in the downregulation of the CYP isoforms. To understand the underlying mechanisms, we assessed the relationship between the expressions of the CYP isoforms and those of their regulating transcription factors [aryl hydrocarbon receptor (AhR), AhR nuclear translocator (ARNT), constitutive androstane receptor (CAR), pregnane X receptor (PXR), and retinoid X receptor (RXR)] in human hepatocytes treated with the HIF-α stabilizers. As a result, the mRNA level of AhR did not decrease, although ARNT expression was repressed. On the other hand, the mRNA expression levels of CAR, PXR, and RXR were repressed and closely associated with those of CYP2B6 and CYP3A4. Although the underlying mechanism of the downregulation for CYP1A2 remains unclear, the presently reported results suggest that the downregulation of CYP2B6 and CYP3A4 via HIF-α stabilization is caused by a decrease in the expressions of CAR, PXR, and RXR. SIGNIFICANCE STATEMENT: We showed that hypoxia-inducible factor (HIF)-α stabilization downregulates CYP1A2, CYP2B6, and CYP3A4 using prolyl hydroxylase domain 2 inhibitors, which are HIF-α stabilizers, as a new tool to mimic hypoxia in human hepatocytes. To understand the underlying mechanisms, we assessed the relationship between the expressions of the CYP isoforms and those of their regulating transcription factors. Our findings would contribute to a better understanding of the hypoxia-triggered regulatory mechanism of drug-metabolizing enzymes in human hepatocytes.

Extrusion of the medial meniscus is a potential predisposing factor for post-arthroscopy osteonecrosis of the knee.

BACKGROUND: Post-arthroscopic osteonecrosis of the knee (PAONK) is a rare condition. No studies have analyzed the relationship between the meniscus extrusion and PAONK. The purpose of this retrospective study is to test a hypothesis that the degree of the medial meniscus (MM) extrusion might be significantly greater in the knees with PAONK than in the matched control knees both before and after the meniscectomy. METHODS: Ten knees with PAONK were detected out of a total of 876 knees which had undergone arthroscopic partial meniscectomy of the MM. Ten matched control knees were randomly selected out of the remaining 866 knees without PAONK. The clinical data of these 20 patients were retrospectively collected from the medical records. To evaluate the location of the menisci on the joint line, Extrusion width and Inner width were defined on a coronal section of magnetic resonance imaging (MRI). The intra- and inter-rater reliability was evaluated by calculating the intra- and inter-class coefficients. Statistical comparisons between the 2 groups were made using the 3 non-parametric tests. RESULTS: Before the meniscectomy, the Extrusion width of the MM (mean 4.7 ± 1.4 mm) was significantly greater than that (3.0 ± 1.3 mm) in the Control group (P = 0.0195). In the MRI taken in a range from 3 to 50 weeks after the meniscectomy, the Extrusion width of the MM (5.9 ± 1.1 mm) in the PAONK group was significantly greater than that (3.4 ± 1.4 mm) in the Control group (P = 0.0009), and the Inner width of the MM (0.6 ± 1.7 mm) in the PAONK group was significantly less than that (3.9 ± 1.0 mm) in the Control group (P = 0.0001). CONCLUSION: A significant relationship was found between the degree of the MM extrusion and the onset of PAONK. This study suggested that the extrusion of the MM is a potential predisposing factor for PAONK.

Imaging Mass Microscopy of Kidneys from Azithromycin-Treated Rats with Phospholipidosis.

Drug-induced phospholipidosis is a lysosomal storage disorder characterized by the excess accumulation of tissue phospholipids. Although azithromycin can be used to induce phospholipidosis, no experimental studies evaluating the relationship between drug accumulation and phospholipid localization have been performed. In this study, azithromycin was orally administered to rats for 7 days, and the relationship between drug and phospholipid accumulation was performed using imaging mass microscopy. The administration of azithromycin induced tubular epithelial vacuolation in the inner stripe of the outer medulla of the kidney, consistent with the lamellar bodies that are typical manifestations of drug-induced phospholipidosis. Azithromycin and phospholipid tissue levels were extensively elevated in the kidneys of azithromycin-treated rats. Imaging mass microscopy revealed that both azithromycin and its metabolites were found in the kidneys of azithromycin-treated rats but not in control animals. The vacuolated areas of the kidneys were primarily found in the inner stripe of the outer medulla, consistent with the areas of high azithromycin concentration. Azithromycin was colocalized with several phospholipids-phosphatidylinositol (18:0/20:4), phosphatidylethanolamine (18:0/20:4 and 16:0/20:4), and possibly didocosahexaenoyl (C22:6)-bis(monoacylglycerol) phosphate, a putative biomarker of drug-induced phospholipidosis. In summary, we found correlations between regions of kidney damage and the accumulation of azithromycin, its metabolites, and phospholipids using imaging mass microscopy. Such analyses may help reveal the mechanism and identify putative biomarkers of drug-induced phospholipidosis.

The impact of intergenerational programs on social capital in Japan: a randomized population-based cross-sectional study.

BACKGROUND: Over the last several decades, social isolation and loneliness among older adults have posed an increasingly urgent challenge due to the rapidly aging population in Japan. To remedy the situation, many communities have introduced intergenerational programs. However, few studies have investigated the benefits of social capital across generations as a result of intergenerational interaction between children and older generations. Therefore, we aim to ascertain the degree to which intergenerational programs that take root in a community will affect the social capital of all generations in the community. METHODS: We focus our research on one specific program, REPRINTS, an intergenerational health promotion program for older adults that has been active for over 10 years in Tama Ward, Kawasaki City, Kanagawa Prefecture. We conducted a population-based cross-sectional study of residents between the ages of 20 and 84 years who were randomly selected from the basic resident register. Approximately 2500 residents were selected, of which 978 responded; data from 891 respondents were analyzed. RESULTS: Hierarchical linear modeling suggests that the duration of programs was a significant community-level indicator of neighborhood trust. At the individual level, people between 30 and 59 years of age and people over 60 years of age have more positive effects on neighborhood trust than do people between 20 and 39 years of age. CONCLUSIONS: The ongoing intergenerational programs between older citizens and children can enforce neighborhood trust, thus strengthening a community's intergenerational ties. The REPRINTS program has been developed through cooperation with local citizens, senior volunteers, and teachers from the community. Its collaborative nature ensures longevity and continuous growth in a community. It is challenging to create long-term intergenerational programs that take root in communities, making persistence and collaboration a crucial factor in fruitful intergenerational relationships. Overall, ongoing intergenerational program implementation associates with building social capital, thereby strengthening potential intergenerational ties and promote mutual support among local residents which will reduce or prevent social isolation among older.

Systematic synthetic study of four diastereomerically distinct limonene-1,2-diols and their corresponding cyclic carbonates.

In order to produce versatile and potentially functional terpene-based compounds, a (R)-limonene-derived diol and its corresponding five-membered cyclic carbonate were prepared. The diol (cyclic carbonate) comprises four diastereomers based on the stereochemical configuration of the diol (and cyclic carbonate) moiety. By choosing the appropriate starting compounds (trans- and cis-limonene oxide) and conditions, the desired diastereomers were synthesised in moderate to high yields with, in most cases, high stereoselectivity. Comparison of the NMR data of the obtained diols and carbonates revealed that the four different diastereomers of each compound could be distinguished by reference to their characteristic signals.

No Sex-Specific Differences in the Acute Antidepressant Actions of (R)-Ketamine in an Inflammation Model.

Background: Although previous reports suggest sex-specific differences in the antidepressant actions of (R,S)-ketamine, these differences in the antidepressant actions of (R)-ketamine, which is more potent than (S)-ketamine, are unknown. Methods: Saline or (R)-ketamine was administered 23 hours post lipopolysaccharide administration to adult male or female mice. Subsequently, antidepressant effects were assessed using a forced swimming test. Furthermore, the concentration of (R)-ketamine and its 2 major metabolites, (R)-norketamine and (2R,6R)-hydroxynorketamine, was measured in the plasma and brain after the administration of (R)-ketamine in the mice. Results: (R)-ketamine (10 mg/kg) significantly attenuated the increased immobility time of forced swimming test in the lipopolysaccharide-treated mice. There were no sex-specific differences in the concentrations of (R)-ketamine and its 2 metabolites in the plasma and brain. Conclusions: These findings showed no sex-specific differences in terms of the acute antidepressant effects and pharmacokinetic profile of (R)-ketamine.

Antidepressant Potential of (R)-Ketamine in Rodent Models: Comparison with (S)-Ketamine.

The rapid-acting and long-lasting antidepressant effects of (R,S)-ketamine have recently gained much attention. Although (S)-ketamine has been studied as an active isomer, recent evidence suggests that (R)-ketamine exhibits longer-lasting antidepressant effects than (S)-ketamine in rodents. However, the antidepressant potential of (R)-ketamine has not been fully addressed. In the present study, we compared the antidepressant effects of (R)-ketamine with those of (S)-ketamine in animal models of depression, including a model that is refractory to current medications. Both (R)-ketamine and (S)-ketamine exhibited antidepressant effects at 30 minutes as well as at 24 hours after administration in forced-swimming and tail-suspension tests in mice. At 48 hours after administration, however, (R)-ketamine still exerted a significant antidepressant effect in the tail-suspension test, whereas the effect of (S)-ketamine was no longer observed. Moreover, (R)-ketamine, but not (S)-ketamine, significantly reversed the depressive-like behavior induced by repeated treatments with corticosterone in rats at 24 hours after a single administration. This effect was attenuated by an α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor antagonist, suggesting the involvement of AMPA receptor stimulation in the effects. Both (R)-ketamine and (S)-ketamine exhibited practically the same exposure levels in plasma, brain, and cerebrospinal fluid in mice and rats, and both compounds were rapidly eliminated from plasma (<4-8 hours). The present results confirmed the previous findings that (R)-ketamine exerted longer-lasting antidepressant effects than (S)-ketamine in animal models of depression. Moreover, our study is the first to demonstrate that (R)-ketamine exerted a sustained antidepressant effect even in a model that is refractory to currently prescribed antidepressants.

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.

Metabolite profiling and enzyme reaction phenotyping of luseogliflozin, a sodium-glucose cotransporter 2 inhibitor, in humans.

1. To understand the clearance mechanism of luseogliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, we investigated its human metabolite profile and metabolic enzymes responsible for the primary metabolic pathways in human using reaction phenotyping. 2. Sixteen metabolites of luseogliflozin were found in human plasma and/or urine and their structural information indicated that the drug was metabolized via multiple metabolic pathways. The primary metabolic pathways involve (1) O-deethylation to form M2 and subsequent glucuronidation to form M12, (2) ω-hydroxylation at ethoxy group to form M3 followed by oxidation to form the corresponding carboxylic acid metabolite (M17) and (3) direct glucuronidation to form M8. 3. The reaction phenotyping studies indicated that the formation of M2 was mainly mediated by cytochrome P450 (CYP) 3A4/5, and subsequently M12 formation was catalyzed by UGT1A1, UGT1A8 and UGT1A9. The formation of M3 was mediated by CYP4A11, CYP4F2 and CYP4F3B, and the further oxidation of M3 to M17 was mediated by alcohol dehydrogenase and aldehyde dehydrogenase. The formation of M8 was catalyzed by UGT1A1. 4. These results demonstrate that luseogliflozin is metabolized through multiple pathways, including CYP-mediated oxidation and glucuronidation, in human.

Recommendation to Exclude Bile-Duct-Cannulated Rats with Hyperbilirubinemia for Proper Conduct of Biliary Drug Excretion Studies.

Hyperbilirubinemia (HB) is sometimes encountered following bile-duct cannulation in rats. It possibly originates from the reduced functioning of multidrug resistance-associated protein 2 (Mrp2) and subsequent adaptive alterations in the expression of Mrp3 and the organic anion transporting polypeptides (Oatps). Our aim was to clarify the importance of excluding bile-duct-cannulated (BDC) rats with HB for proper conduct of drug excretion studies. We detected HB [serum total bilirubin concentration (TBIL) ≥0.20 mg/dl] in 16% of all BDC rats prepared. The serum activities of aspartate aminotransferase, alanine aminotransferase, leucine aminopeptidase, and alkaline phosphatase were within the respective normal ranges in the BDC rats with mild HB (TBIL, 0.20-0.79 mg/dl), indicating the absence of hepatic failure. In the pharmacokinetics of pravastatin, an Oatps/Mrp2 probe drug in the BDC rats, the apparent volume of distribution and the clearance were smaller in the mild HB group as compared with the normal group, suggesting the reduction of apparent hepatic uptake and hepatobiliary elimination. The biliary excretion (percentage of dose) was significantly reduced by 54%, suggesting that the biliary efflux activity via Mrp2 was reduced to a greater extent relative to metabolic activity in hepatocytes. The serum γ-glutamyltransferase (GGT) activity correlated with TBIL and inversely correlated with biliary excretion of pravastatin, a finding which could serve as a clue to uncover the regulatory system involving cooperation between GGT and Mrp2. In conclusion, BDC rats with HB, however mild, should be excluded from drug excretion studies to avoid the risk of underestimation of the biliary excretion of drugs.

Involvement of organic cation transporters in the clearance and milk secretion of thiamine in mice.

PURPOSE: To investigate the role of organic cation transporters (Octs) and multidrug and toxin extrusion protein 1 (Mate1) in the disposition of thiamine. METHODS: The uptake of [(3)H]thiamine was determined in Oct1-, Oct2-, and Oct3-expressing HEK293 cells and freshly isolated hepatocytes. A pharmacokinetic study of thiamine-d3 following intravenous infusion (1 and 100 nmol/min/kg) was conducted in male Oct1/2(+/+) and Oct1/2(-/-) mice. A MATE inhibitor, pyrimethamine, (5 mg/kg) was administered intravenously. The plasma and breast milk concentrations of thiamine were determined in female mice. RESULTS: Thiamine is a substrate of Oct1 and Oct2, but not Oct3. Oct1/2 defect caused a significant reduction in the uptake of [(3)H]thiamine by hepatocytes in vitro, and elevated the plasma thiamine concentration by 5.8-fold in vivo. The plasma clearance of thiamine-d3 was significantly decreased in Oct1/2(-/-) mice. At the higher infusion rate of 100 nmol/min/kg thiamine-d3, Oct1/2 defect or pyrimethamine-treatment caused a significant reduction in the renal clearance of thiamine-d3. The total thiamine and thiamine-d3 concentrations were moderately reduced in the intestine of Oct1/2(-/-) mice but were unchanged in the kidney, liver, or brain. The milk-to-plasma concentration ratio of thiamine was decreased by 28-fold in the Oct1/2(-/-) mice. CONCLUSIONS: Oct1 is possibly responsible for the plasma clearance of thiamine via tissue uptake and for milk secretion. Oct1/2 and Mate1 are involved in the renal tubular secretion of thiamine.

Preclinical metabolism and disposition of luseogliflozin, a novel antihyperglycemic agent.

1. We investigated the metabolism and disposition of luseogliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, in rats and dogs, as well as in vitro metabolism in rats, dogs and humans. In addition, we studied its localization in the rat kidney. 2. [14C]Luseogliflozin was rapidly and well absorbed (>86% of the dose) after oral administration to rats and dogs. The drug-derived radioactivity was mainly excreted via the feces in both species. 3. The predominant radioactivity component in the excreta was associated with the metabolites, with only a minor fraction of unchanged luseogliflozin. The major metabolites were two glucuronides (M8 and M16) in the rats, and the O-deethylated form (M2) and other oxidative metabolites (M3 and M17) in the dogs. 4. The in vitro metabolism in dog and human hepatocytes was significantly slower than that in the rat hepatocytes. The biotransformation in animal hepatocytes was similar to that observed in vivo. Incubation with human hepatocytes resulted in the formation of metabolites, including M2, M3, M8 and M17, via multiple metabolic pathways. 5. [14C]Luseogliflozin was well-distributed to its target organ, the kidney, and was found to be localized in the renal cortex, which shows SGLT2 expression. This characteristic distribution was inhibited by preinjection of phlorizin, an SGLT inhibitor, suggesting that the renal radioactivity was associated with SGLT2.

A Strategy for assessing potential drug-drug interactions of a concomitant agent against a drug absorbed via an intestinal transporter in humans.

A strategy for assessing potential drug-drug interactions (DDIs) based on a simulated intestinal concentration is described. The proposed prediction method was applied to the DDI assessment of luseogliflozin, a novel antidiabetic drug, against miglitol absorbed via the intestinal sodium-glucose cotransporter 1 (SGLT1). The method involves four steps: collection of physicochemical and pharmacokinetic parameters of luseogliflozin for use in a computer simulation; evaluation of the validity of these parameters by verifying the goodness of fit between simulated and observed plasma profiles; simulation of the intestinal luseogliflozin concentration-time profile using the Advanced Compartment Absorption and Transit (ACAT) model in a computer program and estimation of the time spent above a value 10-fold higher than the IC50 value (TAIC) for SGLT1; and evaluation of the DDI potential of luseogliflozin by considering the percentage of TAIC against the miglitol Tmax (time for Cmax) value (TAIC/Tmax). An initial attempt to prove the validity of this method was performed in rats. The resulting TAIC/Tmax in rats was 32%, suggesting a low DDI potential of luseogliflozin against miglitol absorption. The validity was then confirmed using an in vivo interaction study in rats. In humans, luseogliflozin was expected to have no DDI potential against miglitol absorption, since the TAIC/Tmax in humans was lower than that in rats. This prediction was proven, as expected, in a clinical interaction study. In conclusion, the present strategy based on a simulation of the intestinal concentration-time profile using dynamic modeling would be useful for assessing the clinical DDI potential of a concomitant agent against drugs absorbed via an intestinal transporter.

Takotsubo cardiomyopathy in siblings.

We report the case of apical ballooning syndrome (ABS) in a female sibling. A 64-year-old woman was admitted to our hospital with sudden-onset chest pain. Cardiac enzymes were mildly elevated and an electrocardiogram showed broad ST-T changes. Emergency coronary angiography revealed no culprit lesion and left ventriculography demonstrated focal akinesis of the apical wall, which was consistent with ABS. Myocardial functional sympathetic innervations assessed using [(123)I]metaiodobenzylguanidine was severely impaired in the apical region. Her clinical symptoms and cardiac dysfunction recovered spontaneously. Just 1 year prior to our patient's cardiac event, her elder sister had the same symptoms and was also diagnosed with ABS. Both sisters were postmenopausal. The familial case of ABS is exceedingly rare, but these cases suggest a possible genetic etiology.

A sensitive and selective method for the quantitative analysis of miglitol in rat plasma using unique solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry.

A sensitive, selective and robust liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of miglitol in rat plasma. The sample preparation procedures involved protein precipitation and unique solid-phase extraction, which efficiently removed sources of ion suppression and column degradation interference present in the plasma. Chromatographic separation was achieved on an amide column using 10 mmol/L CH3 COONH4 and CH3 CN:CH3 OH (90:10, v/v) as the mobile phase under gradient conditions. Detection was performed using tandem mass spectrometry equipped with an electrospray ionization interface in positive ion mode.The selected reaction monitoring transitions for miglitol and a stable isotope-labeled internal standard were m/z 208 → m/z 146 and m/z 212 → m/z 176, respectively. The correlation coefficients of the calibration curves ranged from 0.9984 to 0.9993 over a concentration range of 0.5-100 ng/mL plasma. The quantification limit of the proposed method was more than 10 times lower than those of previously reported LC-MS/MS methods. The novel method was successfully validated and applied to a pharmacokinetic study in rats.

SGLT2 inhibitor lowers serum uric acid through alteration of uric acid transport activity in renal tubule by increased glycosuria.

Sodium glucose cotransporter 2 (SGLT2) inhibitors have been reported to lower the serum uric acid (SUA) level. To elucidate the mechanism responsible for this reduction, SUA and the urinary excretion rate of uric acid (UE(UA)) were analysed after the oral administration of luseogliflozin, a SGLT2 inhibitor, to healthy subjects. After dosing, SUA decreased, and a negative correlation was observed between the SUA level and the UE(UA), suggesting that SUA decreased as a result of the increase in the UE(UA). The increase in UE(UA) was correlated with an increase in urinary D-glucose excretion, but not with the plasma luseogliflozin concentration. Additionally, in vitro transport experiments showed that luseogliflozin had no direct effect on the transporters involved in renal UA reabsorption. To explain that the increase in UE(UA) is likely due to glycosuria, the study focused on the facilitative glucose transporter 9 isoform 2 (GLUT9ΔN, SLC2A9b), which is expressed at the apical membrane of the kidney tubular cells and transports both UA and D-glucose. It was observed that the efflux of [(14) C]UA in Xenopus oocytes expressing the GLUT9 isoform 2 was trans-stimulated by 10 mm D-glucose, a high concentration of glucose that existed under SGLT2 inhibition. On the other hand, the uptake of [(14) C]UA by oocytes was cis-inhibited by 100 mm D-glucose, a concentration assumed to exist in collecting ducts. In conclusion, it was demonstrated that the UE(UA) could potentially be increased by luseogliflozin-induced glycosuria, with alterations of UA transport activity because of urinary glucose.