Pharmacokinetics of fluconazole after oral administration to healthy beagle dogs.

BACKGROUND: Fluconazole can be effective in the treatment of superficial mycoses in dogs. However, the pharmacokinetics of fluconazole have not yet been evaluated to determine its optimal dosing regimen. OBJECTIVES: This study aimed to determine the plasma concentration of fluconazole after single and multiple administrations at two different dosages in dogs. METHODS AND MATERIALS: Eight healthy beagle dogs were divided into two groups, and each group received either 5 or 10 mg/kg of fluconazole per os. The pharmacokinetics of fluconazole was determined following single and multiple administrations p.o. Single- and multiple-dose treatment periods were separated by a washout period of seven days. Plasma concentrations of fluconazole were determined by established high-performance liquid chromatography coupled with tandem mass spectrometry system. RESULTS: In the 5 mg/kg group, the mean maximum concentrations (Cmax ) and the area under the plasma concentrations (AUC0-24h ) were 4.84 µg/mL and 85.56 µg*h/mL, respectively, after single administration and 6.58 µg/mL and 119.52 µg*h/mL, respectively, after multiple administrations. In the 10 mg/kg group, the Cmax and AUC0-24h were 5.67 µg/mL and 109.19 µg*h/mL, respectively, after single administration and 15.10 µg/mL and 291.51 µg*h/mL, respectively, after multiple administrations. The Cmax (p < 0.001) and AUC0-24h (p < 0.001) were significantly lower in the 5 mg/kg group than those in the 10 mg/kg group at multiple administrations. CONCLUSIONS AND CLINICAL RELEVANCE: Fluconazole accumulates in plasma and exhibits dose-proportional pharmacokinetics after multiple doses, and was safe and well tolerated at these doses for short-term administration.

Engineering Yarrowia lipolytica for de novo production of tetraacetyl phytosphingosine.

AIMS: To genetically engineer the oleaginous yeast Yarrowia lipolytica for de novo production of tetraacetylphytosphingosine (TAPS), a precursor of phytosphingosine, and optimization of fermentation conditions for high yield. METHODS AND RESULTS: We successfully constructed a TAPS-producing Y. lipolytica CE3 strain by co-expression of Wickerhamomyces ciferrii-derived acetyl transferases, Sli1p and Atf2p. Next, we optimized several environmental factors including temperature, initial pH and C/N ratio for TAPS production in a shake culture. Deletion of LCB4 in CE3 strain increased the volumetric TAPS titre and cell-specific yield to 142·1 ± 10·7 mgTAPS  l-1 and 3·08 ± 0·11 mgTAPS  gDCW -1 , respectively, in a shake flask culture incubated for 120 h at 28°C with glycerol as the carbon source. Finally, we developed a 5-l fed-batch process with NaOH-mediated pH control and olive oil as a carbon source, exhibiting 650 ± 24 mgTAPS  l-1 of TAPS production within 56 h of the fermentation. CONCLUSIONS: The introduction of codon-optimized Sli1p and Atf2p, deletion of LCB4 gene and sexual hybridization, accompanied by specific fermentation conditions, enhanced TAPS yield in Y. lipolytica. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results highlight Y. lipolytica as a promising candidate for the industrial production of TAPS, an important component of cosmetic formulations.

Structure-based modification of pyrazolone derivatives to inhibit mTORC1 by targeting the leucyl-tRNA synthetase-RagD interaction.

The enzyme leucyl-tRNA synthetase (LRS) and the amino acid leucine regulate the mechanistic target of rapamycin (mTOR) signaling pathway. Leucine-dependent mTORC1 activation depends on GTPase activating protein events mediated by LRS. In a prior study, compound BC-LI-0186 was discovered and shown to interfere with the mTORC1 signaling pathway by inhibiting the LRS-RagD interaction. However, BC-LI-0186 exhibited poor solubility and was metabolized by human liver microsomes. In this study, in silico physicochemical properties and metabolite analysis of BC-LI-0186 are used to investigate the addition of functional groups to improve solubility and microsomal stability. In vitro experiments demonstrated that 7b and 8a had improved chemical properties while still maintaining inhibitory activity against mTORC1. The results suggest a new strategy for the discovery of novel drug candidates and the treatment of diverse mTORC1-related diseases.

Inhibition of Skin Inflammation by Scytonemin, an Ultraviolet Sunscreen Pigment.

Scytonemin is a yellow-green ultraviolet sunscreen pigment present in different genera of aquatic and terrestrial blue-green algae, including marine cyanobacteria. In the present study, the anti-inflammatory activities of scytonemin were evaluated in vitro and in vivo. Topical application of scytonemin inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear swelling in BALB/c mice. The expression of tumor necrosis factor-a (TNF-a) and inducible nitric oxide synthase (iNOS) was also suppressed by scytonemin treatment in the TPA-treated ear of BALB/c mice. In addition, scytonemin inhibited lipopolysaccharide (LPS)-induced production of TNF-a and nitric oxide (NO) in RAW 264.7 cells, a murine macrophage-like cell line, and the mRNA expressions of TNF-a and iNOS were also suppressed by scytonemin in LPS-stimulated RAW 264.7 cells. Further study demonstrated that LPS-induced NF-kB activity was significantly suppressed by scytonemin treatment in RAW 264.7 cells. Our results also showed that the degradation of IkBa and nuclear translocation of the p65 subunit were blocked by scytonemin in LPS-stimulated RAW 264.7 cells. Collectively, these results suggest that scytonemin inhibits skin inflammation by blocking the expression of inflammatory mediators, and the anti-inflammatory effect of scytonemin is mediated, at least in part, by down-regulation of NF-kB activity. Our results also suggest that scytonemin might be used as a multi-function skin care ingredient for UV protection and anti-inflammation.

A Machine Learning-Based Identification of Genes Affecting the Pharmacokinetics of Tacrolimus Using the DMETTM Plus Platform.

Tacrolimus is an immunosuppressive drug with a narrow therapeutic index and larger interindividual variability. We identified genetic variants to predict tacrolimus exposure in healthy Korean males using machine learning algorithms such as decision tree, random forest, and least absolute shrinkage and selection operator (LASSO) regression. rs776746 (CYP3A5) and rs1137115 (CYP2A6) are single nucleotide polymorphisms (SNPs) that can affect exposure to tacrolimus. A decision tree, when coupled with random forest analysis, is an efficient tool for predicting the exposure to tacrolimus based on genotype. These tools are helpful to determine an individualized dose of tacrolimus.

Extrapolation of In Vivo Hepatic Clearance from In Vitro Uptake Clearance by Suspended Human Hepatocytes for Anionic Drugs with High Binding to Human Albumin: Improvement of In Vitro-to-In Vivo Extrapolation by Considering the "Albumin-Mediated" Hepatic Uptake Mechanism on the Basis of the "Facilitated-Dissociation Model".

We investigated whether human serum albumin (HSA) in suspended human hepatocytes would affect the uptake clearance of anionic drugs with high binding to HSA and improve the extrapolation of in vivo hepatic clearance from in vitro uptake clearance by the hepatocytes via the "albumin-mediated" hepatic uptake mechanism. The uptake clearances for total forms (PS inf) and for unbound forms (PS u,inf) of 11 anionic drugs [all of which were organic anion-transporting polypeptide (OATP) substrates] were determined with suspended human hepatocytes in varying concentrations of HSA. The fraction of unbound drugs (f u) was determined using an equilibrium dialysis at the various HSA concentrations. The PS inf values decreased with increasing concentrations of HSA, whereas the unbound uptake clearances (PS u,inf(+) = PS inf/ f u) in the presence of HSA increased substantially, thus demonstrating the "albumin-mediated" hepatic uptake mechanism. The relationships between PS inf and HSA concentration were well described by the previously proposed facilitated-dissociation model, in which the drug-albumin complex interacts with the cell surface, enhancing the dissociation of the complex and providing unbound drug for hepatic uptake. Furthermore, the PS u,inf (+) values in in vivo conditions (at 5% HSA) were predicted from those obtained in isolated hepatocytes on the basis of the facilitated-dissociation model, revealing compatibility with the overall hepatic intrinsic clearance in vivo. We conclude that the "facilitated-dissociation" model is useful for describing the "albumin-mediated" hepatic uptake phenomenon of OATP drugs and to predict hepatic uptake clearance in vivo.

Model-based pharmacokinetic and pharmacodynamic analysis for acute effects of a small molecule inhibitor of diacylglycerol acyltransferase-1 in the TallyHo/JngJ polygenic mouse.

The purpose of this study was to evaluate the acute effect of a small molecule inhibitor of DGAT-1 on triglycerides (TG) and cholesterol in polygenic type 2 diabetic TallyHo/JngJ (TH) mice. PF-04620110, a potent and selective DGAT-1 inhibitor, was used as a model compound in this study and which was administered to TH and ICR mice. The concentration of the model compound that produced 50% of maximum lowering of TG level (IC50) in TH mice was not significantly different from that in ICR mice, when estimated using the model-based pharmacokinetic and pharmacodynamic assay, a two-compartmental model and an indirect response model. The clearance of the inhibitor in TH mice was fivefold higher than that in ICR mice, suggesting significantly altered pharmacokinetics. Moreover, the in vitro metabolic elimination kinetic parameters (ke,met), determined using liver microsomes from TH and ICR mice were 1.24 ± 0.14 and 0.174 ± 0.116 min-1, respectively. Thus, we report that the differences in the acute effects of the small molecule DAGT-1 inhibitor between TH mice and ICR mice can be attributed to altered pharmacokinetics caused by an altered metabolic rate for the compound in TH mice.

Determination of Penicillium griseofulvum-oriented pyripyropene A, a selective inhibitor of acyl-coenzyme A:cholesterol acyltransferase 2, in mouse plasma using liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies.

In this study, we developed a method for the determination of Penicillium griseofulvum-oriented pyripyropene A (PPPA), a selective inhibitor of acyl-coenzyme A:cholesterol acyltransferase 2, in mouse and human plasma and validated it using liquid chromatography-tandem mass spectrometry. Pyripyropene A (PPPA) and an internal standard, carbamazepine, were separated using a Xterra MS C18 column with a mixture of acetonitrile and 0.1% formic acid as the mobile phase. The ion transitions monitored in positive-ion mode [M + H]+ of multiple-reaction monitoring (MRM) were m/z 148.0 from m/z 584.0 for PPPA and m/z 194.0 from m/z 237.0 for the internal standard. The detector response was specific and linear for PPPA at concentrations within the range from 1 to 5,000 ng/mL. The intra-/inter-day precision and accuracy of the method was acceptable by the criteria for assay validation. The matrix effects of PPPA ranged from 97.6 to 104.2% and from 93.3 to 105.3% in post-preparative mouse and human plasma samples, respectively. PPPA was also stable under various processing and/or handling conditions. Finally, PPPA concentrations in the mouse plasma samples could be measured after intravenous, intraperitoneal, or oral administration of PPPA, suggesting that the assay is useful for pharmacokinetic studies on mice and applicable to human studies.

The Phenomenon of Albumin-Mediated Hepatic Uptake of Organic Anion Transport Polypeptide Substrates: Prediction of the In Vivo Uptake Clearance from the In Vitro Uptake by Isolated Hepatocytes Using a Facilitated-Dissociation Model.

The effects of bovine serum albumin and human serum albumin on the unbound hepatic uptake clearance (PSu,inf) of the organic anion-transporting polypeptide substrates 1-anilino-8-naphthalene sulfonate (ANS) and pitavastatin (PTV) were determined using primary cultured rat hepatocytes and isolated human hepatocytes, respectively. The PSu,inf value of hepatocytes was estimated by dividing the initial uptake rate of these anions by their unbound concentrations. The PSu,inf values for ANS and PTV were enhanced in the presence of albumin, thereby demonstrating the phenomenon of "albumin-mediated" hepatic uptake. We previously constructed a "facilitated-dissociation" model, in which the interaction of the ligand-albumin complex with the cell surface enhanced the dissociation of that complex to provide unbound ligand for uptake to the hepatocytes [J Pharmacokinet Biopharm 16:165-181 (1988)]. That model was able to describe accurately the relationship between the enhancement of the PSu,inf values and the albumin concentration. By considering the enhancement of hepatic uptake clearance by albumin using this facilitated-dissociation model, we could predict accurately the PSu,inf in vivo from that obtained in isolated hepatocytes. In the light of these findings, we suggest that the facilitated-dissociation model is applicable to describing the phenomenon of albumin-mediated hepatic uptake via organic anion transporters and to evaluating hepatic uptake clearance in vivo.

Pharmacokinetics of tafamidis, a transthyretin amyloidosis drug, in rats.

1. We characterized the pharmacokinetics of tafamidis, a novel drug to treat transthyretin-related amyloidosis, in rats after intravenous and oral administration at doses of 0.3-3 mg/kg. In vitro Caco-2 cell permeability and liver microsomal stability, as well as in vivo tissue distribution and plasma protein binding were also examined. 2. After intravenous injection, systemic clearance (CL), volumes of distribution at steady state (Vss) and half-life (T½) remained unaltered as a function of dose, with values in the ranges of 6.41-7.03 mL/h/kg, 270-354 mL/kg and 39.5-46.9 h, respectively. Following oral administration, absolute bioavailability was 99.7-104% and was independent of doses from 0.3 to 3 mg/kg. In the urine and faeces, 4.36% and 48.9% of tafamidis, respectively, were recovered. 3. Tafamidis was distributed primarily in the liver and not in the brain, kidney, testis, heart, spleen, lung, gut, muscle, or adipose tissue. Further, tafamidis was very stable in rat liver microsomes, and its plasma protein binding was 99.9%. 4. In conclusion, tafamidis showed dose-independent pharmacokinetics with intravenous and oral doses of 0.3-3 mg/kg. Tafamidis undergoes minimal first-pass metabolism, distributes mostly in the liver and plasma, and appears to be eliminated primarily via biliary excretion.

Specific Inhibition of the Distribution of Lobeglitazone to the Liver by Atorvastatin in Rats: Evidence for a Rat Organic Anion Transporting Polypeptide 1B2-Mediated Interaction in Hepatic Transport.

Cytochrome P450 enzymes and human organic anion transporting polypeptide (OATP) 1B1 are reported to be involved in the pharmacokinetics of lobeglitazone (LB), a new peroxisome proliferator-activated receptor γ agonist. Atorvastatin (ATV), a substrate for CYP3A and human OATP1B1, is likely to be coadministered with LB in patients with the metabolic syndrome. We report herein on a study of potential interactions between LB and ATV in rats. When LB was administered intravenously with ATV, the systemic clearance and volume of distribution at steady state for LB remained unchanged (2.67 ± 0.63 ml/min per kg and 289 ± 20 ml/kg, respectively), compared with that of LB without ATV (2.34 ± 0.37 ml/min per kg and 271 ± 20 ml/kg, respectively). Although the tissue-to-plasma partition coefficient (Kp) of LB was not affected by ATV in most major tissues, the liver Kp for LB was decreased by ATV coadministration. Steady-state liver Kp values for three levels of LB were significantly decreased as a result of ATV coadministration. LB uptake was inhibited by ATV in rat OATP1B2-overexpressing Madin-Darby canine kidney cells and in isolated rat hepatocytes in vitro. After incorporating the kinetic parameters for the in vitro studies into a physiologically based pharmacokinetics model, the characteristics of LB distribution to the liver were consistent with the findings of the in vivo study. It thus appears that the distribution of LB to the liver is mediated by the hepatic uptake of transporters such as rat OATP1B2, and carrier-mediated transport is involved in the liver-specific drug-drug interaction between LB and ATV in vivo.

In vitro and in vivo anti-inflammatory effects of a novel 4,6-bis ((E)-4-hydroxy-3-methoxystyryl)-1-phenethylpyrimidine-2(1H)-thione.

Inflammation plays a critical defensive role in the human body. However, uncontrolled or aberrant inflammatory responses contribute to various acute and chronic diseases. The Nrf2-ARE pathway plays a pivotal role in the regulation of inflammatory markers, such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). On the basis of this concept, we synthesized a novel anti-inflammatory 4,6-bis ((E)-4-hydroxy-3-methoxystyryl)-1-phenethylpyrimidine-2(1H)-thione (HPT), and in vitro experiments using HepG2-C8 ARE-luciferase-transfected cells demonstrated the induction of Nrf2-ARE activity. In lipopolysaccharide (LPS)-induced RAW 264.7 cells, HPT treatment reduced the production of nitric oxide (NO) as well as the protein and mRNA expression levels of COX-2 and iNOS, in a dose-dependent manner. In addition, HPT suppressed the mRNA expression of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, and IL-6. In LPS-induced macrophages, HPT inhibited COX-2 and iNOS by blocking the activation of p38 and c-Jun NH2-terminal kinase (JNK) but not extracellular signal-regulated kinase (ERK1/2). Furthermore, an in vivo anti-inflammatory study was performed using a TPA-induced skin inflammation mouse model, and the results showed that HPT reduced TPA-induced inflammation and attenuated the expression of COX-2 and iNOS in TPA-induced mouse skin tissue. Thus, HPT demonstrated anti-inflammatory activity both in LPS-induced RAW 264.7 cells and TPA-stimulated mouse skin and may therefore serve as a potential anti-inflammatory agent.

A Phase I, Open-Label, Sequential, Single-Dose Clinical Trial to Evaluate the Pharmacokinetic, Pharmacodynamic, and Safety of IVL3001, a Finasteride-Based Novel Long-Acting Injection for Androgenetic Alopecia.

INTRODUCTION: Hair loss is driven by multiple factors, including genetics. Androgenetic alopecia (AGA) is a condition in which treatments necessitate prolonged compliance with prescribed medications. We have developed IVL3001, a long-acting injectable (LAI) formulation of finasteride encapsulated within poly lactic-co-glycolic acid microspheres, to enhance the efficacy of the finasteride and to achieve consistent positive outcomes in adults. An open-label, sequential, single-dose phase I clinical trial was designed to evaluate the safety, pharmacokinetic (PK), and pharmacodynamic (PD) of IVL3001. METHODS: A total of 40 non-smoking, healthy adult males were divided into three cohorts where the IVL3001 group received a single subcutaneous injection of 12-36 mg IVL3001 and 1 mg finasteride (Propecia®) once daily for 28 days. The plasma concentrations of finasteride, dihydrotestosterone (DHT), and testosterone were measured using liquid chromatography-tandem mass spectrometry. The tolerability of the injections was assessed, and compartment models were developed to predict the effective dose and assess PK/PD profiles. RESULTS: IVL3001 and finasteride 1 mg tablets were well tolerated. IVL3001 showed consistent plasma concentrations without bursts or fluctuations. Consistent with its mechanism of action, IVL3001 reduced DHT levels. Simulation data showed that the administration of 12-36 mg of IVL3001 every 4 weeks achieved plasma concentrations similar to finasteride, with comparable DHT reduction. CONCLUSION: The present study represents the first clinical trial to evaluate the safety, pharmacokinetic (PK), pharmacodynamic (PD), and tolerability of finasteride long-acting injectables (LAI) in adults. The rapid onset of action sustained effective drug concentration and the prolonged half-life of IVL3001 suggest that it offers multiple benefits over conventional oral formulations in terms of therapeutic response and compliance. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT04945226.

Roles of breast cancer resistance protein and organic anion transporting polypeptide 2B1 in gastrointestinal toxicity induced by SN-38 under inflammatory conditions.

Drug transporters are among the factors that determine the pharmacokinetic profiles after drug administration. In this study, we investigated the roles of drug transporters involved in transport of SN-38, which is an active metabolite of irinotecan, in the intestine under inflammatory conditions in vitro and determined their functional consequences. The expression alterations of breast cancer resistance protein (BCRP) and organic anion transporting polypeptide (OATP) 2B1 were determined at the mRNA and protein levels, and the subsequent functional alterations were evaluated via an accumulation study with the representative transporter substrates [prazosin and dibromofluorescein (DBF)] and SN-38. We also determined the cytotoxicity of SN-38 under inflammatory conditions. Decreased BCRP expression and increased OATP2B1 expression were observed under inflammatory conditions in vitro, which led to altered accumulation profiles of prazosin, DBF, and SN-38, and the subsequent cytotoxic profiles of SN-38. Treatment with rifampin or novobiocin supported the significant roles of BCRP and OATP2B1 in the transport and cytotoxic profile of SN-38. Collectively, these results suggest that BCRP and OATP2B1 are involved in the increased cytotoxicity of SN-38 under inflammatory conditions in vitro. Further comprehensive research is warranted to completely understand SN-38-induced gastrointestinal cytotoxicity and aid in the successful treatment of cancer with irinotecan.

Pharmacokinetic interactions of niclosamide in rats: Involvement of organic anion transporters 1 and 3 and organic cation transporter 2.

Niclosamide is an anthelmintic drug with a long history of use and is generally safe and well tolerated in humans. As the conventional dose of niclosamide results in a low but certain level in systemic circulation, drug interactions with concomitant drugs should be considered. We aimed to investigate the interaction between niclosamide and drug transporters, as such information is currently limited. Niclosamide inhibited the transport activity of OATP1B1, OATP1B3, OAT1, OAT3, and OCT2 in vitro. Among them, the inhibitory effects on OAT1, OAT3, and OCT2 were strong, with IC50 values of less than 1 µM. When 3 mg/kg of niclosamide was co-administered to rats, systemic exposure to furosemide (a substrate of OAT1/3) and metformin (a substrate of OCT2) increased, and the renal clearance (CLr) of the drugs significantly decreased. These results suggest that niclosamide inhibits renal transporters, OAT1/3 and OCT2, not only in vitro but also in vivo, resulting in increased systemic exposure to the substrates of the transporters by strongly blocking the urinary elimination pathway in rats. The findings of this study will support a meticulous understanding of the transporter-mediated drug interactions of niclosamide and consequently aid in effective and safe use of niclosamide.

Proline-Hinged α-Helical Peptides Sensitize Gram-Positive Antibiotics, Expanding Their Physicochemical Properties to Be Used as Gram-Negative Antibiotics.

The outer membrane (OM) of Gram-negative bacteria is the most difficult obstacle for small-molecule antibiotics to reach their targets in the cytosol. The molecular features of Gram-negative antibiotics required for passing through the OM are that they should be positively charged rather than neutral, flat rather than globular, less flexible, or more increased amphiphilic moment. Because of these specific molecular characteristics, developing Gram-negative antibiotics is difficult. We focused on sensitizer peptides to facilitate the passage of hydrophobic Gram-positive antibiotics through the OM. We explored ways of improving the sensitizing ability of proline-hinged α-helical peptides by adjusting their length, hydrophobicity, and N-terminal groups. A novel peptide, 1403, improves the potentiation of rifampicin in vitro and in vivo and potentiates most Gram-positive antibiotics. The "sensitizer" approach is more plausible than those that rely on conventional drug discovery methods concerning drug development costs and the development of drug resistance.

Evaluation of Drug Blood-Brain-Barrier Permeability Using a Microfluidic Chip.

The blood-brain-barrier (BBB) is made up of blood vessels whose permeability enables the passage of some compounds. A predictive model of BBB permeability is important in the early stages of drug development. The predicted BBB permeabilities of drugs have been confirmed using a variety of in vitro methods to reduce the quantities of drug candidates needed in preclinical and clinical trials. Most prior studies have relied on animal or cell-culture models, which do not fully recapitulate the human BBB. The development of microfluidic models of human-derived BBB cells could address this issue. We analyzed a model for predicting BBB permeability using the Emulate BBB-on-a-chip machine. Ten compounds were evaluated, and their permeabilities were estimated. Our study demonstrated that the permeability trends of ten compounds in our microfluidic-based system resembled those observed in previous animal and cell-based experiments. Furthermore, we established a general correlation between the partition coefficient (Kp) and the apparent permeability (Papp). In conclusion, we introduced a new paradigm for predicting BBB permeability using microfluidic-based systems.

Pharmacokinetic characterization of the novel TAZ modulator TM-25659 using a multicompartment kinetic model in rats and a possibility of its drug-drug interactions in humans.

This study evaluated the pharmacokinetics of the novel TAZ modulator TM-25659 in rats following intravenous and oral administration at dose ranges of 0.5-5 mg/kg and 2-10 mg/kg, respectively. Plasma protein binding, plasma stability, liver microsomal stability, CYP inhibition, and transport in Caco-2 cells were also evaluated. After intravenous injection, systemic clearance, steady-state volumes of distribution, and half-life were dose-independent, with values ranging from 0.434-0.890 mL · h(-1) · kg(-1), 2.02-4.22 mL/kg, and 4.60-7.40 h, respectively. Mean absolute oral bioavailability was 50.9% and was not dose dependent. Recovery of TM-25659 was 43.6% in bile and <1% in urine. In pharmacokinetic modeling studies, the three-compartment (3C) model was appropriate for understanding these parameters in rats. TM-25659 was stable in plasma. Plasma protein binding was approximately 99.2%, and was concentration-independent. TM-25659 showed high permeation of Caco-2 cells and did not appear to inhibit CYP450. TM-25659 was metabolized in phase I and II steps in rat liver microsomes. In conclusion, the pharmacokinetics of TM-25659 was characterized for intravenous and oral administration at doses of 0.5-5 and 2-10 mg/kg, respectively. TM-25659 was eliminated primarily by hepatic metabolism and urinary excretion.

Determination of PF-04620110, a novel inhibitor of diacylglycerol acyltransferase-1, in rat plasma using liquid chromatography-tandem mass spectrometry and its application in pharmacokinetic studies.

In this study, we developed a method for the determination of PF-04620110 (2-{(1r,4r)-4-[4-(4-amino-5-oxo-7,8-dihydropyrimido[5,4-f][1,4]oxazepin-6(5H)-yl)phenyl]cyclohexyl}acetic acid), a novel diacylglycerol acyltransferase 1 (DGAT-1) inhibitor, in rat plasma and validated it using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Rat plasma samples were processed following a protein precipitation method by using acetonitrile and were then injected into an LC-MS/MS system for quantification. PF-04620110 and imipramine (internal standard) were separated using a Hypersil Gold C18 column, with a mixture of acetonitrile and 10 mm ammonium formate (90:10, v/v) as the mobile phase. The ion transitions monitored in positive-ion mode [M + H](+) of multiple-reaction monitoring were m/z 397.0 → 260.2 for PF-04620110 and m/z 280.8 → 86.0 for imipramine. The detector response was specific and linear for PF-04620110 at concentrations within the range 0.05-50 µg/mL and the signal-to-noise ratios for the samples were ≥10. The intra- and inter-day precision and accuracy of the method matched the acceptance criteria for assay validation. PF-04620110 was stable under various processing and/or handling conditions. PF-04620110 concentrations in the rat plasma samples could be measured up to 24 h after intravenous or oral administration of PF-04620110, suggesting that the assay is useful for pharmacokinetic studies in rats.

Strong inhibition of organic cation transporter 2 by flavonoids and attenuation effects on cisplatin-induced cytotoxicity.

Organic cation transporter 2 (OCT2) is predominantly expressed in the basolateral membrane of renal proximal tubule cells and contributes to the renal excretion of various drugs such as metformin, cisplatin, oxaliplatin, cimetidine, and lamivudine. Cisplatin, an anticancer agent for various cancers, is a substrate of OCT2, and cisplatin-induced nephrotoxicity is in part attributed to OCT2 activity in the kidney, which increases the renal accumulation of cisplatin. In this study, we aimed to identify flavone derivatives with strong inhibitory effects on OCT2 transport. Among the 80 flavonoids tested, 24 showed moderate to strong inhibitory effects against OCT2 transport activity. The IC50 values were less than 5 µM for 10 flavonoids. All 10 compounds alleviated cisplatin-induced cytotoxicity in cells expressing OCT2, even though the magnitude of the effects varied depending on the functional moieties in each position. Multiple factor analysis revealed that the methyl group at the R1 position and methoxy group at the R6 position of the flavonol backbone are important for OCT2 inhibition. Information on the functional moieties in the flavonol backbone would help develop effective OCT2 inhibitors by providing a structural association with OCT2 inhibitory effects. In addition, the compounds with strong inhibitory effects on OCT2 identified in this study may be potential candidates for clinical use to mitigate cisplatin-induced nephrotoxicity.