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Venetoclax, a small molecule inhibitor of BCL-2, has demonstrated efficacy in treating acute leukemias and has been recommended as one of the first-line anti-leukemia therapies. Although venetoclax has been suggested to probably possess the ability to penetrate the central nervous system (CNS), current data to elucidate the characteristics of venetoclax in cerebrospinal fluid (CSF), bone marrow (BM), and plasma are still lacking. This study investigated the real-world characteristics of venetoclax concentrations in CSF, BM, and plasma in acute leukemia patients. Thirteen acute leukemia patients treated with venetoclax were included, with paired samples of CSF, BM, and plasma collected and venetoclax concentrations measured using LC-MS/MS. With the results, the median venetoclax concentrations were 2030 ng/mL in plasma, 16.7 ng/mL in CSF, and 1390 ng/mL in BM. The percentages of CSF/plasma and BM/plasma were 0.74% and 70.37%, respectively. While no direct correlation was observed between CSF and plasma venetoclax levels, there was a trend toward an improved CSF/plasma percentage over time following the last administration of venetoclax. In contrast, a strong correlation was found between BM and plasma levels. This study demonstrated that venetoclax could reach its effective concentration in most patients, suggesting its potential clinical utility in the management of CNS involvement in acute leukemia., (© 2024 The Author(s). Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Objective: The aim of this study was to establish a simple and sensitive high-performance liquid chromatography method for therapeutic drug monitoring of venetoclax (VEN) and optimize regimens., Methods: The analysis required the extraction of a 50 μl plasma sample and the precipitation of proteins using acetonitrile extraction. The chromatographic method employed a mobile phase of acetonitrile: 0.5% KH 2 PO 4 (pH 3.5) (60/40, v/v) on a Diamond C 18 (4.6 mm × 250 mm, 5 μm) column at a flow rate of 1.0 ml/min. The quantitative method was validated based on standards described in 'Bioanalytical Method Validation: Guidance for Industry' published by the US Food and Drug Administration (FDA)., Results: The calibration curve was linear ( R2  = 0.9998) over the range of 75-4800 ng/ml, with limits of quantification of 25 ng/ml. The coefficients of intraday and interday validation, specificity, recovery, and stability all met the criteria of FDA guidance. The method was successfully applied to analyze VEN concentrations in 30 cases of acute myeloid leukemia patients. The peak concentration ( Cmax ) was 1881.19 ± 756.61 ng/ml, while the trough concentration ( Cmin ) was 1212.69 ± 767.92 ng/ml in acute myeloid leukemia patients., Conclusion: Our study establishes a simple, precise, and sensitive high-performance liquid chromatography method for monitoring VEN and confirms its applicability for therapeutic drug monitoring of VEN in hematological cancers., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

The primary aim was to demonstrate bioequivalence between the 10/20 mg fixed-dose combination (FDC) of macitentan/tadalafil in a single tablet and the free combination of both drugs, and to evaluate the food effect on the 10/20 mg FDC in healthy participants. In this single-center, randomized, open-label, 3-way crossover, single-dose Phase 1 study in healthy adult participants, macitentan/tadalafil was administered as a 10/20 mg FDC formulation and compared with the free combination of macitentan and tadalafil. The food effect on the FDC was also evaluated. Pharmacokinetic sampling (216 h) was conducted. The 90% confidence intervals (CIs) for the geometric mean ratios of maximum observed plasma analyte concentration (C max ) and area under the plasma analyte concentration-time curves (AUCs) for Treatment A (FDC, fasted) versus C (free combination, fasted) were within bioequivalence limits demonstrating that the FDC formulation can be considered bioequivalent to the free combination. The 90% CIs for the geometric mean ratios of C max and AUC for Treatment B (FDC, fed) versus A (FDC, fasted) were contained within bioequivalence limits demonstrating that there was no food effect. The administration of the 10/20 mg FDC was generally safe and well tolerated in healthy participants. This study demonstrated bioequivalence between the FDC of macitentan/tadalafil (10/20 mg) in a single tablet and the free combination of both drugs in healthy participants, and that the FDC can be taken without regard to food, similarly to the individual components. The FDC was generally safe and well tolerated., (© 2024 Actelion Pharmaceuticals Ltd. Pharmacology Research & Perspectives published by British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics and John Wiley & Sons Ltd.)

A liquid chromatography-tandem mass spectrometry method with vonoprazan fumarate-d4 as a stable isotope-labeled internal standard was developed and validated aiming at quantification of vonoprazan fumarate in human plasma for a bioequivalence study. Chromatographic separation was achieved by acetonitrile one-step protein precipitation using a gradient elution of 0.1% formic acid aqueous solution and acetonitrile with a run time of 3.65 min. Detection was carried out on a tandem mass spectrometer in multiple reaction monitoring mode via a positive electrospray ionization interface. The multiple reaction monitoring mode of precursor-product ion transitions for vonoprazan fumarate and vonoprazan fumarate-d4 were m/z 346.0 → 315.1 and 350.0 → 316.0, respectively. The linear range was 0.150-60.000 ng/ml. This method was fully validated with acceptable results in terms of selectivity, carryover, lower limit of quantification, calibration curve, accuracy, precision, dilution effect, matrix effect, stability, recovery and incurred sample reanalysis. A successful application of this method was realized in the bioequivalence study of vonoprazan fumarate tablet (20 mg) among healthy Chinese volunteers., (© 2024 John Wiley & Sons, Ltd.)

The integration of pain management in veterinary practice, driven by heightened animal welfare concerns, extends to avian species where subtle and nonspecific behavioral signs pose challenges. Given that safety concerns with classical NSAIDs highlight the need for more targeted alternatives in birds, this study explores the pharmacokinetic (PK) properties of Deracoxib (DX), a COX-2 selective NSAID approved for use in dogs, following a single oral administration in geese. Six healthy female geese received 4 mg/kg DX. Blood was drawn from the left wing vein to heparinized tubes at 0, 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 10, and 24 h. Plasma DX concentrations were measured using HPLC coupled to an UV detector, and the data were pharmacokinetically analyzed using PKanalix™ software in a non-compartmental approach. The results indicated a terminal half-life of 6.3 h and a T max of 1 h, with no observed adverse effects. While refraining from claiming absolute safety based on a single dose, it is worth highlighting that further safety studies for DX in geese are warranted, suggesting a possibility for intermittent use. In addition, drawing conclusions on efficacy and suitability awaits further research, particularly in understanding COX-2 selectivity and protein binding characteristics specific to geese., (© 2024 John Wiley & Sons Ltd.)

The combination regimen targeting BRAF and MEK inhibition, for instance, encorafenib (Braftovi ™ , ENF) plus binimetinib (Mektovi ® , BNB), are now recommended as first-line treatment in patients with unresectable or metastatic melanoma with a BRAF V600-activating mutation. Patients treated with combination therapy of ENF and BNB demonstrated a delay in resistance development, increases in antitumor activity, and attenuation of toxicities compared with the activity of either agent alone. However, the pharmacokinetic profile of the FDA-approved ENF and BNB is still unclear. In this study, a rapid and sensitive LC-MS/MS bioanalytical method for simultaneous quantification of ENF and BNB in rat plasma was developed and validated. Chromatography was performed on an Agilent Eclipse plus C18 column (50 mm × 2.1 mm, 1.8 µm), with an isocratic mobile phase composed of 0.1% formic acid in water/acetonitrile (67:33, v / v , pH 3.2) at a flow rate of 0.35 mL/min. A positive multiple reaction monitoring (MRM) mode was chosen for detection and the process of analysis was run for 2 min. Plasma samples were pre-treated using protein precipitation with acetonitrile containing spebrutinib as the internal standard (IS). Method validation was assessed as per the FDA guidelines for the determination of ENF and BNB over concentration ranges of 0.5-3000 ng/mL (r 2 ≥ 0.997) for each drug (plasma). The lower limits of detection (LLOD) for both drugs were 0.2 ng/mL. The mean relative standard deviation (RSD) of the results for accuracy and precision was ≤ 7.52%, and the overall recoveries of ENF and BNB from rat plasma were in the range of 92.88-102.28%. The newly developed approach is the first LC-MS/MS bioanalytical method that can perform simultaneous quantification of ENF and BNB in rat plasma and its application to a pharmacokinetic study. The mean result for C max for BNB and ENF was found to be 3.43 ± 0.46 and 16.42 ± 1.47 µg/mL achieved at 1.0 h for both drugs, respectively. The AUC 0-∞ for BNB and ENF was found to be 18.16 ± 1.31 and 36.52 ± 3.92 µg/mL.h, respectively. On the other hand, the elimination half-life (t 1/2kel ) parameters for BNB and ENF in the rat plasma were found to be 3.39 ± 0.43 h and 2.48 ± 0.24 h, and these results are consistent with previously reported values.

This work presents an end-to-end approach for assessing the absolute bioavailability of highly hydrophobic, poorly water-soluble compounds that exhibit high nonspecific binding using venetoclax as a model drug. The approach utilizes a stable labeled i.v. microdose and requires fewer resources compared with traditional approaches that use radioactive 14 C-labeled compounds. The stable labeled venetoclax and internal standard were synthesized, then an i.v. formulation was developed. In the clinical study, female subjects received a single oral dose of venetoclax 100 mg followed by a 100-µg i.v. dose of cold-labeled 13 C-venetoclax at the oral time of maximum concentration (T max ). The i.v. microdose was prepared as an extemporaneous, sterile compounded solution on the dosing day by pharmacists at the clinical site. Several measures were taken to ensure the sterility and safety of the i.v. preparation. A sensitive liquid chromatography-tandem mass spectrometry method was developed to allow the detection of plasma levels from the i.v. microdose. Plasma samples were collected through 72 h, and pharmacokinetic parameters were estimated using noncompartmental methods. Postdosing sample analysis demonstrated the consistency of the preparations and allowed the precise calculation of the pharmacokinetic parameters based on the actual injected dose. The absolute bioavailability of venetoclax was estimated at 5.4% under fasting conditions. Venetoclax extraction ratio was estimated to be 0.06 suggesting that the fraction transferred from the enterocytes into the liver is limiting venetoclax bioavailability. The proposed framework can be applied to other highly hydrophobic, poorly water-soluble compounds that exhibit high nonspecific binding to support the understanding of their absorption and disposition mechanisms and guide formulation development., (© 2021 AbbVie Inc. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

S-epacadostat (S-EPA) is an efficient and selective small-molecule inhibitor of indoleamine 2,3-dioxygenase 1. It is an EPA analog with a sulfur atom instead of a nitrogen atom at the furazan C3 position. This study documents the pharmacokinetics of S-EPA in dogs and its metabolic pathway. After an oral administration of 15 mg/kg of S-EPA in dogs, the time to peak concentration was 0.80 h, the mean elimination half-life was 7.3 h, and the absolute bioavailability was 55.8%. Furthermore, we identified S-EPA metabolites in dog plasma and dog liver microsomes by UPLC-Q Exactive Orbitrap HRMS. In dog plasma, we found five metabolites, which came from glucuronidation (M1 and M2), deoxygenation (the amidine M4), glucuronidation of M4 (M3), and desulfonamidation and oxidation of M4 (the carboxylic acid M5). In dog liver microsomes, we identified three major metabolites, namely, the glucuronide conjugate (M6), a mono-oxidation product (M7), and a desulfonamidation and oxidation product (M8). Gut microbiota may cause the differences between in vivo and in vitro oxidation metabolisms. Contrary to EPA, S-EPA did not undergo dealkylation, suggesting that substituting the nitrogen with sulfur affects the metabolism of the adjacent alkyl side chain., (© 2021 John Wiley & Sons, Ltd.)

The COVID-19 pandemic has forced clinical studies to accommodate imposed limitations. In this study, the bioequivalence part could not be conducted as planned. Thus, the aim was to demonstrate bioequivalence, using an adaptive study design, of tadalafil in fixed-dose combination (FDC) tablets of macitentan/tadalafil with single macitentan and tadalafil (Canadian-sourced) tablets and assess the effect of food on FDC tablets in healthy subjects. This Phase 1, single-center, open-label, single-dose, two-part, two-period, randomized, crossover study enrolled 62 subjects. Tadalafil bioequivalence as part of FDC of macitentan/tadalafil (10/40 mg) with single-component tablets of macitentan (10 mg) and tadalafil (40 mg) was determined by pharmacokinetic (PK) assessment under fasted conditions. The effect of food on FDC was evaluated under fed and fasted conditions. Fasted 90% confidence intervals (CIs) for geometric mean ratios (GMRs) were within bioequivalence limits for tadalafil and macitentan. Fed and fasted 90% CIs for area under the curve (AUC) GMR were within bioequivalence limits. However, 90% CIs for maximum plasma concentration (C max ) GMR for macitentan and tadalafil were outside bioequivalence limits. One FDC-treated subject experienced a serious adverse event of transient ischemic attack (bioequivalence part). To address pandemic-imposed limitations, an adaptive study design was implemented to demonstrate that the FDC tablet was bioequivalent to the free combination of macitentan and tadalafil (Canadian-sourced). No clinically significant differences in PK were determined between fed and fasted conditions; the FDC formulation could be taken irrespective of meals. The FDC formulation under fasted and fed conditions was well tolerated with no clinically relevant differences in safety profiles between the treatment groups. NCT Number: NCT04235270., (© 2021 The Authors. Pharmacology Research & Perspectives published by John Wiley & Sons Ltd, British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics.)

Tissue repair and healing remain among the most complicated processes that occur during postnatal life. Humans and other large organisms heal by forming fibrotic scar tissue with diminished function, while smaller organisms respond with scarless tissue regeneration and functional restoration. Well-established scaling principles reveal that organism size exponentially correlates with peak tissue forces during movement, and evolutionary responses have compensated by strengthening organ-level mechanical properties. How these adaptations may affect tissue injury has not been previously examined in large animals and humans. Here, we show that blocking mechanotransduction signaling through the focal adhesion kinase pathway in large animals significantly accelerates wound healing and enhances regeneration of skin with secondary structures such as hair follicles. In human cells, we demonstrate that mechanical forces shift fibroblasts toward pro-fibrotic phenotypes driven by ERK-YAP activation, leading to myofibroblast differentiation and excessive collagen production. Disruption of mechanical signaling specifically abrogates these responses and instead promotes regenerative fibroblast clusters characterized by AKT-EGR1., (© 2021. The Author(s).)

A two-dimensional MoS 2 nanosheet was prepared by a chemical exfoliation method and served as an excellent matrix for the detection of small molecules by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In comparison with organic matrices (CHCA, 3-AQ) and a graphene matrix, we found that a MoS 2 matrix showed better performance in analysis of amino acids, peptides, fatty acids, and sulfonamides. A systematic comparison of the MoS 2 matrix with both ion modes showed that mass spectra produced in negative ion mode featured a corresponding single deprotonated ion, which was rather different from the complex multiple alkali metal addition peaks present in positive ion mode. In addition, better sensitivity and reproducibility were obtained in negative ion mode. The ionization mechanism of MoS 2 as a matrix in negative ion mode was further discussed. The deproton peak intensity of the analyte fatty acid decreased after the addition of the hole-scavenger KSCN, indicating that the ionization of the fatty acid was caused by the Auger complex effect of MoS 2 and electron injection. Experiments have shown that the MoS 2 matrix detects small molecules with good repeatability and can perform semiquantitative analysis of sulfonamides. Finally, the MoS 2 matrix was employed for quantitative determination of sulfamethoxine in serum samples by an internal standard method. This MoS 2 -assisted laser desorption/ionization mass spectrometry (MoS 2 -assisted LDI MS) method provides a simple, rapid, high-throughput approach to evaluate the drug levels in the patient serum and can achieve convenient drug therapy monitoring.

Background: Pazopanib is widely used to treat renal cell carcinomas and soft tissue tumors in Japan. Pazopanib has significant therapeutic efficacy but it is associated with frequent severe adverse effects. Therapeutic drug monitoring (TDM) may help to prevent adverse effects. A more convenient and rapid pazopanib assay is desirable for the application of TDM in clinical settings. In this study, the authors developed a high-throughput method for quantifying pazopanib in human plasma using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS)., Methods: After a simple solid-phase extraction step using a 96-well plate, pazopanib was analyzed by UHPLC-MS/MS in the positive electrospray ionization mode., Results: The novel method fulfilled the requirements of the US Food and Drug Administration and the European Medicines Agency guidelines for assay validation, and the lower limit of quantification was 0.5 mcg/mL. The calibration curves were linear over the concentration range of 0.5-100 mcg/mL. The average recovery rate was 102.0% ± 3.9% (mean ± SD). The precision was below 5.0%, and the accuracy was within 12.0% for all quality control levels. Matrix effect varied between 90.9% and 97.1%. This assay was successfully applied to TDM of pazopanib trough concentrations in 3 patients treated with the drug for soft tissue tumors., Conclusions: The authors succeeded in developing a novel high-throughput UHPLC-MS/MS method for quantifying pazopanib in human plasma. This method can be applied to TDM of patients receiving pazopanib in clinical settings., Competing Interests: The authors declare no conflict of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Encorafenib (Braftovi) is indicated for the treatment of adult patients with unresectable or metastatic melanoma with a BRAF V600 mutation, in combination with binimetinib (Mektovi). According to the product label of encorafenib, there are no specific treatment recommendations in case of an overdose. We report on a 63-year-old man who ingested a double dose (900 mg) of encorafenib for 16 days. He developed overall minor chronic overdose symptoms such as nausea and vomiting grade 1 and muscle pain. Based on the most occurring adverse events of encorafenib, liver values, kidney function parameters and QTc interval were measured. Kidney function parameters were normal, whereas liver values were slightly increased (grade 1) and QTc slightly prolonged. The plasma concentration 3 h after the last dose was 2110 ng/mL. We describe the course of a case with a chronic overdose during 16 days of the double dose of encorafenib as well as the followed approach, which could be taken into account when observing an encorafenib overdose. Providing information in times of Covid-19 is challenging, but remains necessary for good clinical care., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

TPN729 is a novel phosphodiesterase 5 (PDE5) inhibitor used to treat erectile dysfunction in men. Our previous study shows that the plasma exposure of metabolite M3 (N-dealkylation of TPN729) in humans is much higher than that of TPN729. In this study, we compared its metabolism and pharmacokinetics in different species and explored the contribution of its main metabolite M3 to pharmacological effect. We conducted a combinatory approach of ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry-based metabolite identification, and examined pharmacokinetic profiles in monkeys, dogs, and rats following TPN729 administration. A remarkable species difference was observed in the relative abundance of major metabolite M3: i.e., the plasma exposure of M3 was 7.6-fold higher than that of TPN729 in humans, and 3.5-, 1.2-, 1.1-fold in monkeys, dogs, and rats, respectively. We incubated liver S9 and liver microsomes with TPN729 and CYP3A inhibitors, and demonstrated that CYP3A was responsible for TPN729 metabolism and M3 formation in humans. The inhibitory activity of M3 on PDE5 was 0.78-fold that of TPN729 (The IC 50 values of TPN729 and M3 for PDE5A were 6.17 ± 0.48 and 7.94 ± 0.07 nM, respectively.). The plasma protein binding rates of TPN729 and M3 in humans were 92.7% and 98.7%, respectively. It was astonishing that the catalyzing capability of CYP3A4 in M3 formation exhibited seven-fold disparity between different species. M3 was an active metabolite, and its pharmacological contribution was equal to that of TPN729 in humans. These findings provide new insights into the limitation and selection of animal model for predicting the clinical pharmacokinetics of drug candidates metabolized by CYP3A4.

Purpose: Therapeutic drug monitoring (TDM) is widely used in clinical practice to maximize drug efficacy and minimize toxicities. Currently, it is also practiced in the use of oral molecular targeted drugs. The objective of this study was to assess the clinical importance of measuring the systemic concentration of oral molecular targeted drugs used to treat renal cell carcinoma (RCC)., Methods: The systemic concentrations of the oral molecular targeted drugs sorafenib, sunitinib, axitinib, pazopanib, and everolimus used for RCC were useful for therapeutic interventions, and clinical outcomes were evaluated retrospectively., Results: The interventional use of systemic drug concentration was confirmed in 26 of 87, and their categories are presented. The systemic concentration of sunitinib was useful in dose reduction and/or discontinuation (n = 10), dose escalation (n = 3), and adherence monitoring (n = 2). Nine of the 10 patients whose dose was reduced showed reduced adverse event. Two patients who were intervened in adherence monitor showed improved adherence. For axitinib, dose reduction and/or discontinuation (n = 1) and dose escalation (n = 6) were confirmed. For pazopanib, dose reduction and/or discontinuation (n = 1) and drug interaction detection (n = 1) were confirmed, both of them were confirmed to have reduced adverse events. For everolimus, dose reduction and/or discontinuation (n = 1) and drug interaction detection (n = 1) were confirmed, a patient with reduced dose recovered from adverse events. Interventions for sorafenib were not identified., Conclusions: This study demonstrated that systemic concentrations of oral molecular targeted drugs for RCC were considered to be clinically useful for dose adjustment, monitoring of treatment adherence, and the detection of drug interactions. Moreover, this information could be successfully used to guide individualized therapy to maximize the antitumor effects of these drugs.

Purpose: The purpose of the present study was to investigate the effects of vonoprazan on the pharmacokinetics of venlafaxine in vitro and in vivo., Methods: The mechanism underlying the inhibitory effect of vonoprazan on venlafaxine was investigated using rat liver microsomes. In vitro, the inhibition was evaluated by determining the production of O-desmethylvenlafaxine. Eighteen male Sprague-Dawley rats were randomly divided into three groups: control group, vonoprazan (5 mg/kg) group, and vonoprazan (20 mg/kg) group. A single dose of 20 mg/kg venlafaxine was administrated to rats orally without or with vonoprazan. Plasma was prepared from blood samples collected via the tail vein at different time points and concentrations of venlafaxine and its metabolite, O-desmethylvenlafaxine, were determined by ultra-performance liquid chromatography-tandem mass spectrometry., Results: We observed that vonoprazan could significantly decrease the amount of O-desmethylvenlafaxine (IC 50 = 5.544 μM). Vonoprazan inhibited the metabolism of venlafaxine by a mixed inhibition, combining competitive and non-competitive inhibitory mechanisms. Compared with that in the control group (without vonoprazan), the pharmacokinetic parameters of venlafaxine and its metabolite, O-desmethylvenlafaxine, were significantly increased in both 5 and 20 mg/kg vonoprazan groups, with an increase in MR O-desmethylvenlafaxine ., Conclusion: Vonoprazan significantly alters the pharmacokinetics of venlafaxine in vitro and in vivo. Further investigations should be conducted to check these effects in humans. Therapeutic drug monitoring of venlafaxine in individuals undergoing venlafaxine maintenance therapy is recommended when vonoprazan is used concomitantly., Competing Interests: The authors report no conflicts of interest in this work., (© 2020 Chen et al.)

The objective of this phase 1 study was to evaluate the pharmacokinetics, safety, and tolerability of baricitinib after single and multiple doses in healthy Chinese adults. Eligible subjects received a once-daily dose of baricitinib 2, 4, or 10 mg or placebo on day 1 (single dose) and days 4 through 10 for 7 consecutive days (multiple doses). Plasma pharmacokinetic samples were collected up to 48 hours after dosing on days 1 and 10, with predose samples collected before dosing on day 1 and days 4 through 10. Safety and tolerability were also assessed. Baricitinib was rapidly absorbed, reaching peak plasma concentrations within 0.5 to 1 hour (median). Plasma concentrations declined rapidly following the attainment of peak concentrations, with a mean terminal half-life of 5.7 to 7.3 hours. Steady-state plasma concentrations of baricitinib were achieved after the second day of once-daily dosing, with minimal accumulation of baricitinib in plasma (up to 10% increase in area under the plasma concentration-time curve). Single- and multiple-dose mean values for area under the plasma concentration-time curve from time zero to infinity and maximum plasma concentration appeared to increase in an approximately dose-proportional manner across the dose range. Single and multiple oral doses of once-daily baricitinib up to 10 mg were well tolerated by healthy Chinese subjects., (© 2020 The Authors. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Acinetobacter baumannii is a nosocomial pathogen of urgent concern for public health due to rising rates of multidrug and pandrug resistance. In the context of environmental cues such as growth in human serum, A. baumannii is known to display adaptive efflux, in which a multitude of efflux-associated genes are upregulated, resulting in efflux-mediated drug tolerance in strains that are otherwise susceptible to antibiotic therapy. Previously, we identified a sulfonamide-containing scaffold molecule (ABEPI1) that reversed serum-associated antibiotic tolerance in A. baumannii. Herein, we present structure-activity relationship studies on 29 newly synthesized analogues. These molecules were characterized for their ability to potentiate multiple antibiotics in serum, reduce serum-associated ethidium bromide efflux and depolarize bacterial cell membranes. In addition, they were assessed for toxicity to mammalian cells. Collectively, these molecules may represent promising potential adjuvants for use in combination with new and existing antibiotics to treat A. baumannii bacterial infections., (© 2020 Wiley-VCH GmbH.)

A rapid and sensitive analytical method was developed to quantify venetoclax, an oral BH3-mimetic that blocks the anti-apoptotic protein BCL-2, in mouse plasma using ultra-high-performance liquid chromatography with electrospray ionization tandem mass spectrometric detection. Plasma protein precipitation was performed on 5 µL samples, and separation of the analytes was accomplished on an Accucore aQ column using gradient elution at a flow rate of 0.4 mL/min. The calibration curve was linear (R 2  ≥ 0.99) over the concentration range of 5-1,000 ng/mL, and the lower limit of quantitation was 5 ng/mL. The intra-day and inter-day precisions (RSD%) were < 10.5%, and accuracies ranged from 94.4 to 106%. The developed method was successfully applied to pharmacokinetic studies involving serial 30 µL blood sampling from male and female mice after oral administration of venetoclax (10 mg/kg) alone or 30 min after oral administration of ketoconazole (50 mg/kg) or vehicle (PEG400). The observed pharmacokinetic profiles suggest venetoclax undergoes sexually dimorphic disposition in mice. However, regardless of sex, pharmacokinetic studies demonstrated that venetoclax AUC (0-6h) was increased greater than 2-fold with prior administration of ketoconazole. Overall, our pharmacokinetic studies suggest that mice could be a translationally relevant model for the characterization of venetoclax pharmacokinetics. We have developed an analytical method suitable for such murine pharmacokinetic studies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Several small molecule inhibitors (SMIs) have been recently approved for AML patients. These targeted therapies could be more tolerable than classical antineoplastics, but potential drug-drug interactions (DDI) are relatively frequent. Underestimation or lack of appropriate awareness and management of DDIs with SMIs can jeopardize therapeutic success in AML patients, which often require multiple concomitant medications in the context of prior comorbidities or for the prevention and treatment of infectious and other complications. In this systematic review, we analyze DDIs of glasdegib, venetoclax, midostaurin, quizartinib, gilteritinib, enasidenib, and ivosidenib. CYP3A4 is the main enzyme responsible for SMIs metabolism, and strong CYP3A4 inhibitors, such azoles, could increase drug exposure and toxicity; therefore dose adjustments (venetoclax, quizartinib, and ivosidenib) or alternative therapies or close monitoring (glasdegib, midostaurin, and gilteritinib) are recommended. Besides, coadministration of strong CYP3A4 inducers with SMIs should be avoided due to potential decrease of efficacy. Regarding tolerability, QTc prolongation is frequently observed for most of approved SMIs, and drugs with a potential to prolong the QTc interval and CYP3A4 inhibitors should be avoided and replaced by alternative treatments. In this study, we critically assess the DDIs of SMIs, and we summarize best management options for these new drugs and concomitant medications.

Context: Per- and polyfluoroalkyl substances (PFAS) are environmental chemicals linked to weight gain and type 2 diabetes., Objective: We examined the extent to which PFAS plasma concentrations during pregnancy were associated with postpartum anthropometry and biomarkers., Design, Patients, and Measures: We studied women recruited between 1999 and 2002 in the Project Viva prospective cohort with pregnancy plasma concentrations of PFAS, including perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and 2-(N-ethyl-perfluorooctane sulfonamide) acetic acid (EtFOSAA). Three-year postpartum anthropometry measurements were available from 786 to 801 women, blood pressure from 761 women, and blood biomarkers from 450 to 454 women. We used multivariable regression to evaluate the association of log2-transformed PFAS with postpartum anthropometry, blood pressure, and blood biomarkers (leptin, adiponectin, sex hormone binding globulin [SHBG], hemoglobin A1c, interleukin-6 [IL-6], C-reactive protein), adjusting for age, prepregnancy body mass index, marital status, race/ethnicity, education, income, smoking, parity, and breastfeeding history., Results: Pregnancy concentrations of certain PFAS were associated with greater adiposity (eg, 0.4 cm [95% confidence interval [95%CI]: -0.1, 0.9] greater waist circumference per doubling in EtFOSAA; 0.2 cm [95%CI: -0.1, 0.5] greater mid-upper arm circumference per doubling in PFOA; 1.2 mm [95%CI: 0.1, 2.2] thicker sum of subscapular and triceps skinfolds per doubling in PFOS) and higher systolic blood pressure (eg, 1.2 mm Hg [95%CI: 0.3, 2.2] per doubling in PFOS) at 3 years postpartum. Higher EtFOSAA concentrations were also associated with 10.8% higher IL-6 (95%CI: 3.3, 18.9) and 6.1% lower SHBG (95%CI: 0.7, 11.2) per doubling., Conclusions: Pregnancy concentrations of EtFOSAA, PFOS, and PFOA were associated with adverse postpartum cardiometabolic markers., (© Endocrine Society 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

In this paper we show the application of the Tasso OnDemand™, a novel automated sample collection device, in conjunction with volumetric absorptive microsampling (VAMS) for the development of gefapixant, a P2X3 receptor antagonist currently under clinical development for the treatment of refractory and unexplained chronic cough and endometriosis-related pain. A LC-MS/MS bioanalytical method was developed and validated using VAMS to support this development program. This method was utilized in a drug-drug interaction study to establish a mathematical bridging relationship with data obtained from a validated plasma assay used to support the program. The VAMS bioanalytical method and the predictability of the mathematical relationship is reported and discussed here.

Purpose: Fixed-dose combination glecaprevir (GLE) 300 mg + pibrentasvir (PIB) 120 mg is an orally administered once daily antiviral regimen approved for the treatment of hepatitis C virus (HCV) infection. The objective of this study was to evaluate the potential for cardiac repolarization following GLE + PIB administration in healthy adults., Methods: This placebo- and active-controlled, randomized, single-dose, 4-period, 4-sequence crossover study enrolled 48 healthy subjects. The doses of GLE 400 mg + PIB 120 mg were selected to provide exposures comparable to those with the doses that are therapeutic in the HCV-infected population, GLE 300 mg + PIB 120 mg. The doses of GLE 600 mg + PIB 240 mg were selected to provide supratherapeutic exposures without exceeding the exposures of the GLE + PIB maximal tolerated doses. Moxifloxacin 400 mg (active control/open label) was used for confirming the sensitivity of the ECG assay in detecting QTc prolongation. Time-matched plasma concentrations and triplicate ECGs were obtained on treatment days -1 and 1. The primary end point was time-matched, placebo-corrected, baseline-adjusted Fridericia-corrected QT interval (ΔΔQTcF). Pharmacokinetic-pharmacodynamic analyses characterized the relationship between GLE and PIB plasma concentrations and ΔΔQTcF using a linear regression model and linear mixed-effects model. Findings from categorical analyses of ECG-interval data were also summarized. Tolerability was evaluated through adverse-events monitoring, physical examination including vital sign measurements, ECGs, and laboratory tests., Findings: A total of 48 subjects (22 women [46%], 26 men [54%]), were enrolled in the study, and 47 subjects completed all 4 periods. None of the subjects had a change from baseline in QTcF interval of >30 msec or an absolute QTcF interval of >450 msec. Peak ΔΔQTcF values observed at 5 h postdose (T max ) were 2.9 msec (upper 95% confidence limit, 4.9 msec) with the therapeutic dose and 3.1 msec (upper 95% confidence limit, 5.1 msec) with the supratherapeutic dose, with both upper 95% confidence limits well below the 10-msec threshold. Assay sensitivity was confirmed by peak ΔΔQTcF in the positive control (12.8 ms at 2 h postdose). No statistically significant GLE or PIB concentration-dependent effects on ΔΔQTcF were observed. Headache and skin irritation from ECG electrodes were the most commonly reported AEs. No clinically significant vital sign measurements, ECG findings, or laboratory measurements were observed. There were no patterns of T- and U-wave morphologic abnormalities., Implications: The fixed-dose combination regimen of GLE/PIB does not prolong the QTc interval. ClinicalTrials.gov identifier., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The currently approved dose of pazopanib (800 mg) is being re-examined owing to its adverse effects. The aim of this study was to evaluate the relationships among starting or maintenance doses of pazopanib, estimated pazopanib C min , and other clinical factors, including albumin and α-1 acid glycoprotein levels, in soft-tissue sarcoma and renal cell carcinoma. We also determined whether therapeutic drug monitoring of pazopanib concentrations may be used to improve its therapeutic efficacy and prevent adverse effects. Forty patients who received pazopanib for renal cancer or soft-tissue sarcoma at the Hokkaido Cancer Center were evaluated prospectively. C min for pazopanib was calculated based on the measured values from the plasma samples. The efficacy and time to treatment failure were then assessed. The pazopanib maintenance doses were 200 (n = 4), 400 (n = 34), 600 (n = 4), and 800 mg (n = 1). Most patients (65%) who received a 400 mg dose had an effective pazopanib concentration (≧20 µg/mL), whereas 35% of patients who received the 400 mg dose had ineffective concentrations (<20 µg/mL). Logistic regression analysis revealed that only the albumin level was significantly associated with effective pazopanib concentrations (odds ratio: 1.37, p = 0.0234). In conclusion, a dose of 400 mg had been effective and well tolerated in more than half of patients in this study. However, therapeutic drug monitoring is necessary during pazopanib therapy.

Background: The present study aimed to develop and validate a rapid, selective, and reproducible ultra-performance liquid chromatography-tandem mass spectrometry separation method for the simultaneous determination of the levels of parecoxib and its main metabolite valdecoxib in rat plasma. Moreover, this method was applied to investigate the pharmacokinetics of parecoxib and valdecoxib in rats., Methods: Following the addition of celecoxib as an internal standard, one-step protein precipitation by acetonitrile was used for sample preparation. The effective chromatographic separation was carried out using an ACQUITY UPLC®BEH C18 reversed phase column (2.1 mm × 50 mm, 1.7 μm particle size) with acetonitrile and water (containing 0.1% formic acid) as the mobile phase. The procedure was performed in less than 3 min with a gradient elution pumped at a flow rate of 0.4 ml/min. The electrospray ionization source was applied and operated in the positive ion mode and multiple reaction monitoring mode was used for quantification using the following: target fragment ions: m/z 371 → 234 for parecoxib, m/z 315 → 132 for valdecoxib and m/z 382 → 362 for celecoxib., Results: The method validation demonstrated optimal linearity over the range of 50-10,000 ng/ml (r 2  ≥ 0.9996) and 2.5-500 ng/ml (r 2  ≥ 0.9991) for parecoxib and valdecoxib in rat plasma, respectively., Conclusions: The present study demonstrated a simple, sensitive and applicable method for the quantification of parecoxib and its main pharmacologically active metabolite valdecoxib following sublingual vein administration of 5 mg/kg parecoxib in rats.

To compare the pharmacokinetic (PK) properties of the pediatric dispersible tablet formulation of macitentan and the adult film-coated tablet formulation of macitentan in healthy subjects. A randomized, open-label, single-dose, two-sequence, two-period, crossover, Phase 1 study was conducted in 12 healthy adults. Subjects were randomized to one of the two possible treatment sequences A/B or B/A on Day 1 under fasted conditions. Treatment A was a single 10 mg dose of macitentan (film-coated adult formulation) and Treatment B was a single 10 mg dose of macitentan, consisting of two 5 mg dispersible tablets (pediatric formulation). PK sampling over 216 hours was conducted, and PK parameters were derived using non-compartmental methods. For macitentan, geometric means ratio of peak plasma concentrations (C max ), plasma concentration-time curve from zero to the time of the last quantifiable concentration (AUC 0- t ), and plasma concentration-time curve from zero to infinity (AUC 0-∞ ) were 1.140, 0.974, and 0.974, respectively. The corresponding 90% confidence intervals fell entirely within the referenced range of 0.8000 to 1.2500, which is used for evaluation of bioequivalence. These results indicate no significant differences between the pediatric dispersible tablet and the adult film-coated tablet. Both formulations were well tolerated. The pediatric dispersible tablet is biocomparable to the adult film-coated tablet formulation., (© 2020 The Authors. Pharmacology Research & Perspectives published by John Wiley & Sons Ltd, British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics.)

A method for the simultaneous determination of parecoxib and its metabolite valdecoxib in beagle plasma by UPLC-MS/MS was developed and validated. After the plasma was extracted by acetonitrile precipitation, the analytes were separated on an Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) using acetonitrile-formic acid as the mobile phase in gradient mode. The analytes were monitored by multiple reaction monitoring (MRM) in electrospray negative ion mode. The mass transfer pairs were m/z 368.97→119.01 for parecoxib, m/z 312.89→118.02 for valdecoxib, and m/z 379.98→316.02 for celecoxib (internal standard, IS). The correlation coefficients of parecoxib and valdecoxib ranged from 5 to 4000 ng/mL were greater than 0.9998. The recovery of parecoxib and valdecoxib was greater than 82.54%. The inter- and intra-day precision RSD values were 1.36~3.65% and 2.28~5.91%, respectively. The accuracy of RE values were -1.38%~1.96%. Finally, the matrix effect (ME) and stability were also within acceptable criteria. This method had been successfully applied to the pharmacokinetics of parecoxib and valdecoxib in beagle plasma after injection of parecoxib (1.33 mg/kg, intramuscular injection)., Competing Interests: The authors report no conflicts of interest in this work., (© 2020 Li et al.)

ZAK is a new promising target for discovery of drugs with activity against antihypertrophic cardiomyopathy (HCM). A series of 1,2,3-triazole benzenesulfonamides were designed and synthesized as selective ZAK inhibitors. One of these compounds, 6p binds tightly to ZAK protein ( K d = 8.0 nM) and potently suppresses the kinase function of ZAK with single-digit nM (IC 50 = 4.0 nM) and exhibits excellent selectivity in a KINOMEscan screening platform against a panel of 403 wild-type kinases. This compound dose dependently blocks p38/GATA-4 and JNK/c-Jun signaling and demonstrates promising in vivo anti-HCM efficacy upon oral administration in a spontaneous hypertensive rat (SHR) model. Compound 6p may serve as a lead compound for new anti-HCM drug discovery.

Transporter gene knockout models are a practical and widely used tool for pharmacokinetic studies in drug discovery. P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp) are major efflux transporters that control absorption and bioavailability, and are important when determining oral drug disposition. To the best of our knowledge, beyond the rule of five (bRo5) molecules launched on the market to date tend to be substrates for efflux transporters. The purpose of this study is to evaluate in vivo the impact of efflux transporters on the oral absorption process and systemic clearance using rats which lack P-gp and/or Bcrp expression. We administered five bRo5 substrates (asunaprevir, cyclosporine, danoprevir, ledipasvir, and simeprevir) intravenously or orally to wild-type and Mdr1a, Bcrp, and Mdr1a/Bcrp knockout rats, calculated the clearance, oral bioavailability, and absorption rate profile of each substrate, and compared the results. Systemic clearance of the substrates in knockout rats changed within approximately ±40% compared to wild-types, suggesting the efflux transporters do not have a significant influence on clearance in rats. On the other hand, the oral absorption of substrates in the knockout rats, especially those lacking Mdr1a, increased greatly-between 2- and 5-fold more than in wild-types. This suggests that rat efflux transporters, especially P-gp, greatly reduce the oral exposure of these substrates. Moreover, results on the absorption rate-time profile suggest that efflux transporters are constantly active during the absorption period in rats. Transporter knockout rats are a useful in vivo tool for estimating the transporter-mediated disposition of bRo5 molecules in drug discovery.

Endothelin receptor antagonists (ERAs) such as, ambrisentan, macitentan and sitaxentan are primarily used for the treatment of pulmonary arterial hypertension. Considering the rise in endothelin in pre-eclampsia, ERAs may also be useful in its treatment. To evaluate the pharmacokinetics of ERAs, a rapid ultra-performance liquid chromatography tandem mass spectrometry method was developed and validated to determine the concentration of ambrisentan, macitentan and sitaxentan in human plasma. Plasma samples were treated with methanol to induce protein precipitation. A chromatographic separation was performed on a C 18 column using a gradient of methanol-water containing 0.1% formic acid and 0.013% ammonium acetate and a flow rate of 0.5 ml/min. Multiple reaction monitoring was used for quantification. This method was validated in a linear range of 20.28-2028 μg/l for ambrisentan, 4.052-405.2 μg/l for macitentan and 205.4-10 270 μg/l for sitaxentan. The method was successfully validated according to US Food and Drug Administration guidelines to determine the concentrations of macitentan, ambrisentan and sitaxentan in human plasma. This method is now being used for study samples and clinical patient samples., (© 2019 John Wiley & Sons, Ltd.)

Antimicrobial sulfonamides are important medications. However, their use is associated with major immune-mediated drug hypersensitivity reactions with a rate that ranges from 3% to 4% in the general population. The pathophysiology of sulfa-induced drug hypersensitivity reactions is not well understood, but accumulation of reactive metabolites (sulfamethoxazole [SMX] hydroxylamine [SMX-HA] and SMX N-nitrosamine [SMX-NO]) is thought to be a major factor. These reactive metabolites contribute to the formation of reactive oxygen species (ROS) known to cause cellular damage and induce cell death through apoptosis and necroptosis. ROS can also serve as "danger signals," priming immune cells to mount an immunological reaction. We recruited 26 sulfa-hypersensitive (HS) patients, 19 healthy control subjects, and 6 sulfa-tolerant patients to this study. Peripheral blood monocytes and platelets were isolated from blood samples and analyzed for in vitro cytotoxicity, ROS and carbonyl protein formation, lipid peroxidation, and GSH (glutathione) content after challenge with SMX-HA. When challenged with SMX-HA, cells isolated from sulfa-HS patients exhibited significantly (P ≤ .05) higher cell death, ROS and carbonyl protein formation, and lipid peroxidation. In addition, there was a high correlation between cell death in PBMCs and ROS levels. There was also depletion of GSH and lower GSH/GSSG ratios in peripheral blood mononuclear cells from sulfa-HS patients. The amount of ROS formed was negatively correlated with intracellular GSH content. The data demonstrate a major role for oxidative stress in in vitro cytotoxicity of SMX reactive metabolites and indicate increased vulnerability of cells from sulfa-HS patients to the in vitro challenge., (© 2019, The American College of Clinical Pharmacology.)

Background: Venetoclax is a selective inhibitor of B-cell lymphoma-2, which plays a role in the development of various autoimmune diseases including systemic lupus erythematosus. The aim of these analyses was to quantify the exposure-response relationship for venetoclax effects on B-lymphocyte and total lymphocyte counts as pharmacodynamic markers of efficacy and safety, respectively, in women with systemic lupus erythematosus. The developed modeling framework was also used to evaluate venetoclax effects following cyclic, continuous, or induction/maintenance dosing paradigms as potential dosing alternatives in systemic lupus erythematosus., Methods: Serial pharmacokinetic and lymphocyte count data from 73 women enrolled in a phase I study of venetoclax (single doses of 10-500 mg or two cycles of 30-600 mg or placebo once daily for 7 days followed by a 21-day washout) were analyzed using a sequential population pharmacokinetic/pharmacodynamic modeling approach. Simulations to evaluate changes in B-lymphocyte and total lymphocyte counts following different venetoclax dosing scenarios were conducted., Results: Effect of venetoclax plasma exposures on B lymphocytes was described using an indirect linear response model and on total lymphocytes using a maximal response (E max ) with an effect site compartment. Baseline lymphocyte counts were significant covariates on the slope and half maximal inhibitory concentration parameter estimates for the respective models; with higher baseline counts associated with a greater reduction upon treatment with venetoclax. Model simulations showed that continuous dosing with lower doses of venetoclax (e.g., 150 mg daily) are predicted to achieve similar maximal effects on B-lymphocyte counts compared to cyclic dosing with higher doses (e.g., 400 mg 1 week on/3 weeks off); with better recovery of total lymphocyte counts during off-treatment weeks for the cyclic regimens., Conclusions: Venetoclax treatment in women with systemic lupus erythematosus was associated with exposure-dependent reductions in B lymphocytes, and to a lesser extent, total lymphocyte counts. Results from this study support evaluation of B-cell lymphoma-2 inhibitors as potential therapies for the treatment of systemic lupus erythematosus. CLINICALTRIALS.GOV: NCT01686555.

Aim: A sensitive and reliable LC-MS/MS method has been established and validated to the quantitation of rivaroxaban (RIV) and TAK-438 in rat plasma using carbamazepine as internal standard. Results: The procedure of method validation was conducted according to the guidelines of EMA and US FDA. At the same time, the method was applied to pharmacokinetic interactions study between RIV and TAK-438 for the first time. When RIV and TAK-438 co-administration to rats, main pharmacokinetic parameters of TAK-438 like AUC (0-t) , AUC (0-∞) and C max had statistically significant increase. The main pharmacokinetic parameters of RIV have no statistically significant difference (p > 0.05) when co-administered except for t 1/2 (p < 0.01). Conclusion: The results indicated that drug-drug interactions occurred between RIV and TAK-438 when co-administered to rats.

Vonoprazan fumarate (vonoprazan) is a new kind of acid suppressant with potent acid inhibitory effects. Therefore, it has been administered to kidney transplant recipients for treatment or prophylaxis of steroid ulcers, refractory peptic ulcers, and gastroesophageal reflux disease. Because tacrolimus, which is a well-established immunosuppressant for kidney transplantation, and vonoprazan share the CYP3A4 system for metabolism, drug interactions are anticipated upon simultaneous administration. We retrospectively analyzed 52 kidney transplant recipients who were converted from rabeprazole, which has a small effect on the tacrolimus trough blood concentration (C 0 ), to vonoprazan between August 2016 and July 2019. We compared the tacrolimus C 0 /tacrolimus dose (C 0 /D) before and after conversion and serum liver enzymes, serum total bilirubin, and the estimated glomerular filtration rate (eGFR). As a result, mean tacrolimus C 0 /D before and after conversion was 1.98 ± 1.02 and 2.19 ± 1.15 (ng/mL)/(mg/d), respectively, (p < 0.001). Additionally, mean aspartate transaminase (AST) before and after conversion was 18.6 ± 4.2 and 19.6 ± 5.2 IU/L, respectively, (p = 0.037). Mean alanine transaminase (ALT) before and after conversion was 15.8 ± 5.5 and 17.6 ± 7.1 IU/L, respectively, (p = 0.007). Mean eGFR before and after conversion was 50.6 ± 14.4 and 51.4 ± 14.7 mL/min/1.73 m 2 , respectively (p = 0.021). Mean AST, ALT, and eGFR were slightly but significantly elevated within normal ranges after conversion. In conclusion, our study suggests that the mean tacrolimus C 0 /D was elevated significantly by converting from rabeprazole to vonoprazan, but it had little clinical significance. Vonoprazan can be administered safely to kidney transplant recipients receiving tacrolimus.

1. S-EPA is a sulfur-substitution analog of epacadostat (EPA), an effective small molecule indoleamine 2,3-dioxgenase1 (IDO) inhibitor. By in vitro and in vivo experiments, pharmacokinetic differences of two closely related analogs, S-EPA and EPA was investigated in this study. 2. Liver microsomes clearance experiments showed S-EPA had comparable metabolic stability with EPA in rat and human liver microsomes. The whole blood distribution experiments showed the distribution ratio of S-EPA in blood cells to plasma in mice, rats, dogs and monkey was 1.2, 4.8, 2.2 and 40.6, respectively. While the distribution ratio of EPA ranged from 0.94 to 1.30 in mice, rats, dogs and was 3.1 in monkeys. 3. The pharmacokinetic study in rats showed the exposure (AUC last ) of S-EPA in plasma and blood cells was 1.7-fold and 3.9-fold higher than that of EPA, respectively. Moreover, the exposure ratio of S-EPA in blood cells to plasma was 3.7, while the ratio of EPA was 1.6. 4. In CT26 tumor bearing mice, the IDO inhibition of S-EPA and EPA on plasma or tumor kynurenine was generally consistent. And the inhibition ratio could reach at more than 50% at 3 h after single dose, at least lasting up to 8 h.

A simple and highly sensitive bioanalytical method was developed and validated for simultaneous quantification of nimesulide (NSD) and its active metabolite 4-hydroxy-nimesulide (M1) in human plasma by liquid chromatography-tandem mass spectrometer (LC-MS/MS) and applied in a bioequivalence study performed on Indian subjects. The bioanalytical method was carried out by LC-MS/MS with celecoxib (CXB) as an internal standard (IS) using liquid-liquid extraction technique. The chromatographic separation was performed on a reversed-phase Agilent eclipse plus C18 (75 mm × 4.6 mm, particle size 3.5 µm) column with a mobile phase of acetronitrile and water containing 5 mM ammonium formate (9:1, v/v). Method validation and clinical sample were analysed as per USFDA and EMA guidelines and results met the acceptance criteria. The lower limit of quantitation of NSD and M1 was found 10 ng/mL with a large linearity range from 10 to 6000 ng/mL for both NSD and M1 using only 100 µL of plasma and reported no matrix effect. The multiple reaction monitoring transitions of m/z 307.20 → 229.20, m/z 323.00 → 245.00 and m/z 380.20 → 316.20 were used to measure NSD, M1 and CXB (IS), respectively. The assay method was successfully applied for the simultaneous quantification of both NSD and M1 in plasma samples after oral administration of nimesulide 100 mg tablet in healthy human subjects.

Purpose: Fedratinib (SAR302503, TG101348) is an orally administered Janus kinase (JAK) 2-selective inhibitor that is being developed for the treatment of patients with myelofibrosis (MF). The objectives of this analysis were to develop a population pharmacokinetic (PK) model to characterize fedratinib concentration-time profiles in patients with MF, polycythemia vera (PV) and essential thrombocythemia (ET) following oral fedratinib administration; and to investigate the effects of selected covariates on fedratinib PK parameters., Methods: Nonlinear mixed effects modeling was employed in developing a population PK model for fedratinib. Intensive or sparse fedratinib concentration data collected in adult subjects with MF, PV or ET from six studies were pooled, and a total of 452 subjects and 3442 plasma concentration observations were included in the final model., Results: Fedratinib PK in patients with MF/PV/ET was adequately described by a two-compartment structural PK model with first-order absorption incorporating a lag time and first-order elimination. Following oral administration, fedratinib undergoes biphasic disposition and exhibits linear, time-invariant PK at doses of 200 mg and above. Compared to MF/ET patients, PV patients had higher apparent clearance (CL/F) and apparent central volume of distribution. Creatinine clearance was a statistically significant covariate on CL/F, and patients with mild and moderate renal impairment had 10% and 37% increases in fedratinib exposure as compared to patients with normal renal function. No clinically meaningful effect on fedratinib exposure was observed regarding age, body weight, sex, race and liver function., Conclusions: These results should serve as the basis for dose adjustment of fedratinib for special populations.

The characterization of intestinal dissolution of poorly soluble drugs represents a key task during the development of both new drug candidates and drug products. The bicarbonate buffer is considered as the most biorelevant buffer for simulating intestinal conditions. However, because of its complex nature, being the volatility of CO 2 , it has only been rarely used in the past. The aim of this study was to investigate the effect of a biorelevant bicarbonate buffer on intestinal supersaturation and precipitation of poorly soluble drugs using a gastrointestinal (GI) transfer model. Therefore, the results of ketoconazole, pazopanib, and lapatinib transfer model experiments using FaSSIF bicarbonate were compared with the results obtained using standard FaSSIF phosphate . Additionally, the effect of hydroxypropyl methylcellulose acetate succinate (HPMCAS) as a precipitation inhibitor was investigated in both buffer systems and compared to rat pharmacokinetic (PK) studies with and without coadministration of HPMCAS as a precipitation inhibitor. While HPMCAS was found to be an effective precipitation inhibitor for all drugs in FaSSIF phosphate , the effect in FaSSIF bicarbonate was much less pronounced. The PK studies revealed that HPMCAS did not increase the exposure of any of the model compounds significantly, indicating that the transfer model employing bicarbonate-buffered FaSSIF has a better predictive power compared to the model using phosphate-buffered FaSSIF. Hence, the application of a bicarbonate buffer in a transfer model set-up represents a promising approach to increase the predictive power of this in vitrotool and to contribute to the development of drug substances and drug products in a more biorelevant way.

A novel method using UPLC with tandem mass-spectrometric detection (UPLC-MS/MS) with positive electrospray ionization was developed for the detection of the antiarrhythmic drug, dofetilide, in mouse plasma and urine. Protein precipitation was performed on 10 μL of plasma and 2 μL of urine samples using dofetilide-D4 as an internal standard, and separation of the analyte was accomplished on a C18 analytical column with the flow of 0.40 mL/min. Subsequently, the method was successfully applied to determine the pharmacokinetic parameters of dofetilide following oral and intravenous administration. The calibration curve was linear over the selected concentration range (R 2 ≥ 0.99), with a lower limit of quantitation of 5 ng/mL. The intra-day and inter-day precisions, and accuracies obtained from a 5-day validation ranged from 3.00 to 7.10%, 3.80-7.20%, and 93.0-106% for plasma, and 3.50-9.00%, 3.70-10.0%, 87.0-106% for urine, while the recovery of dofetilide was 93.7% and 97.4% in plasma and urine, respectively. The observed pharmacokinetic profiles revealed that absorption is the rate-limiting step in dofetilide distribution and elimination. Pharmacokinetic studies illustrate that the absolute bioavailability of dofetilide in the FVB strain mice is 34.5%. The current developed method allows for accurate and precise quantification of dofetilide in micro-volumes of plasma and urine, and was found to be suitable for supporting in vivo pharmacokinetic studies., (Published by Elsevier B.V.)

Introduction: Venetoclax is a selective B cell lymphoma-2 inhibitor. It is approved for treatment of chronic lymphocytic leukemia and is being investigated for other hematological malignancies. Venetoclax is predominantly eliminated by the liver; therefore, there is a need to investigate the effect of hepatic insufficiency on venetoclax pharmacokinetics., Methods: A phase I study was carried out in 24 women with normal hepatic function or mild, moderate, or severe hepatic impairment (based on Child-Pugh scores), who received a single 50 mg dose of venetoclax with a low-fat meal. Blood samples were collected up to 120 h after venetoclax administration. Pharmacokinetic parameters were estimated using non-compartmental methods., Results: Venetoclax maximum observed plasma concentration (C max ) and area under the plasma concentration-time curve (AUC) in subjects with mild or moderate hepatic impairment were similar to subjects with normal hepatic function. Mean venetoclax AUC in subjects with severe hepatic impairment was 2.3- to 2.7-fold higher than in subjects with normal hepatic function. The half-life of venetoclax in subjects with severe hepatic impairment was approximately two-fold longer than in subjects with normal hepatic function and subjects with mild or moderate hepatic impairment. Unbound fractions of venetoclax in subjects with mild, moderate, and severe hepatic impairment were similar to the subjects with normal hepatic function. No significant adverse safety events were reported., Conclusions: No venetoclax dosage adjustment is required in subjects with mild or moderate hepatic impairment. In subjects with severe hepatic impairment, a 50% dose reduction of venetoclax is recommended to account for higher exposures and the longer half-life.

Macitentan is an endothelin receptor antagonist commonly used in the treatment of pulmonary arterial hypertension (PAH). A novel, rapid, simple and sensitive UPLC-MS/MS method was developed and validated for pharmacokinetic study and the determination of macitentan in PAH patients. Macitentan and bosentan, which are used as internal standards, were detected using atmospheric pressure chemical ionization in positive ion and multiple reaction monitoring mode by monitoring the mass transitions m/z 589.1 → 203.3 and 552.6 → 311.5, respectively. Chromatographic separation was performed on a reverse-phase C18 column (5 μm, 4.6 × 150 mm) with an isocratic mobile phase, which consisted of water containing 0.2% acetic acid-acetonitrile (90:10, v/v) at a flow rate of 1 mL/min. Retention times were 1.97 and 1.72 min for macitentan and IS, respectively. The calibration curve with high correlation coefficient (0.9996) was linear in the range 1-500 ng/mL. The lower limit of quantitation and average recovery values were determined as 1 ng/mL and 89.8%, respectively. This method is the first UPLC-MS/MS method developed and validated for the determination of macitentan from human plasma. The developed analytical method was fully validated for linearity, selectivity, specificity, accuracy, precision, sensitivity, stability, matrix effect and recovery according to US Food and Drug Administration guidelines. The developed method was applied successfully for pharmacokinetic study and the determination of macitentan in PAH patients., (© 2019 John Wiley & Sons, Ltd.)

Background and Objective: As pazopanib plasma trough concentrations are correlated with treatment outcome, we explored whether single nucleotide polymorphisms in the elimination pathway of pazopanib affect systemic pazopanib concentrations., Methods: The decreased function alleles CYP3A4 15389 C > T (*22), ABCB1 3435 C >T, ABCG2 421 C >A, and ABCG2 34G >A were analyzed within a recently developed population-pharmacokinetic model., Results: Incorporation of CYP3A4*22 in the model resulted in a 35% lower clearance for variant carriers (0.18 vs. 0.27 L/h; difference in objective function value: - 9.7; p < 0.005). Simulated median trough concentrations of cancer patients with CYP3A4*22 with 600 mg once daily or 800 mg once daily were 31 and 35 mg/L, respectively. The simulated trough concentrations for the population excluding the CYP3A4*22 carriers after 600 mg once daily or 800 mg once daily were 18 and 20 mg/L, respectively., Conclusion: This analysis shows that CYP3A4*22 heterozygotes have a substantial lower pazopanib clearance and that dose adjustments based on CYP3A4*22 status could be considered.

Background: Aprocitentan is an orally active, dual endothelin (ET) receptor antagonist developed for the treatment of hypertension in which, despite available treatments, a medical need exists for drugs with a new mechanism of action., Subjects and Methods: In this study, the single- and multiple-dose tolerability, safety, pharmacokinetics (PK), and pharmacodynamics of up to 600 mg (single doses) and 100 mg once a day (qd; multiple doses) of aprocitentan were investigated in healthy male and female subjects. The effect of age on the tolerability and PK parameters was investigated at a dose of 100 mg qd., Results: Aprocitentan was well tolerated across all doses. No serious adverse events (AEs) occurred. The most frequently reported AE was headache. Small increases in body weight were recorded in subjects receiving 100 mg qd. Plasma concentration-time profiles of aprocitentan were similar after single- and multiple-dose administration, and support a qd dosing regimen based on a half-life of 44 hours. After multiple doses, PK was dose proportional. Accumulation at steady state, reached by Day 8, was 3-fold. Only minor differences in exposure between healthy females and males, healthy elderly and adult subjects, and fed and fasted conditions were observed. Plasma ET-1 concentrations, reflecting ET B receptor antagonism, significantly increased with doses ≥25 mg. Time-matched analysis of electrocardiogram (ECG) parameters did not suggest drug-induced ECG effects. Exposure-response analysis indicated no QTc prolongations at plasma levels up to 10 µg/mL., Conclusion: Aprocitentan was well tolerated in healthy subjects with a PK profile favorable for qd dosing., Competing Interests: Disclosure JD is a fellow of the American College of Clinical Pharmacology. PNS and JD are current employees of Idorsia Pharmaceuticals Ltd and former employees of Actelion Pharmaceuticals Ltd. MM is a current employee of Idorsia Pharmaceuticals Ltd. MKK was the principal investigator of the study that was sponsored by Actelion Pharmaceuticals Ltd. The authors report no other conflicts of interest in this work.

The objective of this study was to validate a method for the determination of laromustine (VNP40101M) and short-lived its active metabolite (VNP4090CE) that has a half-life in human blood of <90 s in human plasma by liquid chromatography (LC) with tandem mass spectrometric (MS/MS) detection. We overcome the stability dilemma by acidified the human plasma with citric acid. Laromustine "breaks" down on the source of mass spectrometry to give m/z 249 which is the same m/z for VNP4090CE. Because VNP4090CE and laromustine elute at approximate retention time of 1.93 and 2.94 min, respectively, we were able to quantify both of them in one method. VNP40101M, VNP4090CE and the internal standards were extracted from human plasma by liquid-liquid extraction into ethyl ether. The ethyl ether layer was evaporated, reconstituted and analyzed using LC with MS/MS detection. Validation parameters such as selectivity, limit of quantitation, linearity, precision, accuracy, recovery, autosampler viability, freeze-thaw cycles and compounds stability are evaluated for this method. Results were calculated using peak area ratios, and calibration curves were generated using a weighted (1/x2) linear least-squares regression. Calibration curves for VNP40101M and VNP4090CE in human plasma ranged from 1.00 to 1,000 ng/mL. In this study, both intra- and inter-assay results demonstrated a relative standard deviation for calibration standards (inter-assay) and quality control samples (intra- and inter-assay) to be ≤15.0%. In this method, there is ~1.79% isotopic interference of VNP40101M to VNP40101M-IS, and ~3.76% isotopic interference of VNP4090CE to VNP4090CE-IS. It was concluded that there was no significant carryover.

Equilibrium dialysis has been widely used for the measurement of the fraction of unbound drug (f u ) in plasma, but it suffers from the accuracy and reliability for low f u values. To address this concern, an orthogonal approach, called the bidirectional equilibrium dialysis, is described to simultaneously measure a pair of f u values for each drug based on equilibration in 2 opposite dialysis directions: from plasma to buffer (f u,p/b ) and from buffer to plasma (f u,b/p ). Hypothetically, if true equilibrium is attained in both dialysis directions, the measured f u,b/p and f u,p/b values for a given drug should converge, and thus, the ratio of f u,b/p to f u,p/b becomes unity (1.0). Thus, the ratio can be used as a tangible readout for data reliability. This methodology has been extensively tested in the present study using various drugs with distinct plasma binding characteristics. Our results clearly showed that low f u values (<0.01) could be reliably determined and verified using either the standard or dilution bidirectional equilibrium dialysis method for some known highly bound drugs; for extensively bound drugs with high logD 7.4 , such as montelukast, bedaquiline, and venetoclax, only a range of f u can be reported with confidence because of uncertainty in the true equilibrium., (Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

IG-105, N-(2, 6-dimethoxypyridine-3-yl)-9-methylcarbazole-3-sulfonamide, a novel carbazole sulfonamide, shows a potent anticancer activity in a variety of human tumor cells in vitro and in vivo . In the present study, a rapid and convenient liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed and applied to the pharmacokinetic study of IG-105 in rats. Chromatographic separation was accomplished on a C 18 column using an isocratic mobile phase of acetonitrile-water-acetic acid (56:44:0.2, v/v/v). The ion transitions of IG-105 and combretastatin A4 (internal standard) in selected reaction monitoring mode were m/z 398→154 and m/z 317→286, respectively. The assay exhibited good linearity over the range of 2-512 ng/mL. Intra- and inter-day precisions were within 8.2 %, and the accuracies ranged from -6.0 to 3.7 %. The extraction recoveries were higher than 90 %, and the matrix effects were negligible. All quality control samples were stable at different storage conditions. The validated LC-MS/MS method was successfully applied to a preclinical pharmacokinetic study of IG-105 in rats after a single oral dose of 100, 250, or 1000 mg/kg which showed tumor growth inhibition activity. The absorption of IG-105 was proved to be rapid but saturated to a certain extent into the blood circulation, from where it was distributed and eliminated gradually.

Dasabuvir is mainly metabolized by cytochrome P450 (CYP) 2C8 and is predominantly used in a regimen containing ritonavir. Ritonavir and clopidogrel are inhibitors of CYP3A4 and CYP2C8, respectively. In a randomized, crossover study in 12 healthy subjects, we examined the impact of clinical doses of ritonavir (for 5 days), clopidogrel (for 3 days), and their combination on dasabuvir pharmacokinetics, and the effect of ritonavir on clopidogrel. Clopidogrel, but not ritonavir, increased the geometric mean AUC 0-∞ of dasabuvir 4.7-fold; range 2.0-10.1-fold (P = 8·10 -7 ), compared with placebo. Clopidogrel and ritonavir combination increased dasabuvir AUC 0-∞ 3.9-fold; range 2.1-7.9-fold (P = 2·10 -6 ), compared with ritonavir alone. Ritonavir decreased the AUC 0-4h of clopidogrel active metabolite by 51% (P = 0.0001), and average platelet inhibition from 51% without ritonavir to 31% with ritonavir (P = 0.0007). In conclusion, clopidogrel markedly elevates dasabuvir concentrations, and patients receiving ritonavir are at risk for diminished clopidogrel response., (© 2018 The Authors Clinical Pharmacology & Therapeutics published by Wiley Periodicals, Inc. on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Background: Pazopanib is a tyrosine kinase inhibitor indicated for the treatment of renal cell carcinoma and soft tissue sarcoma. Despite the high inter-patient variability in pharmacokinetic exposure, pazopanib is administered at a fixed dose of 800 mg once daily (QD). Pharmacokinetic exposure is linked to both efficacy and toxicity. In this case report, we illustrate the value of therapeutic drug monitoring by describing two patients with adequate pazopanib trough concentrations (C min ) at an eight times lower than standard dose., Case Presentation: Patient A is a 69-year-old woman with metastatic leiomyosarcoma who had significant toxicities and a high C min on the standard dose. While dose reductions to 200 mg QD and later 200 mg every other day were made, pazopanib C min remained above the efficacy threshold. Patient B is a 50-year-old male with metastatic angiosarcoma and a history of Gilbert syndrome. Pazopanib treatment was initiated at the standard dose of 800 mg QD, but was reduced to 200 mg QD 1-week-on - 1-week-off due to total bilirubin elevation. Pazopanib C min was adequate in this patient as well., Conclusion: It could be valuable to measure pazopanib levels in case of dose reductions due to toxicity, as exposure could still be adequate at considerably lower than standard doses.

Aims: Liver injury can occur during antiviral therapies with direct-acting antivirals (DAAs), potentially necessitating discontinuation of the therapies, with consequent worsening of the sustained viral response (SVR) rates, in patients with hepatitis C virus (HCV). To clarify the mechanisms involved in serum transaminase level elevation, we performed a retrospective evaluation of the serum concentrations of daclatasvir and asunaprevir, both classified as DAAs, in patients receiving treatment with a combination of the two drugs., Methods: Subjects were 278 Japanese patients with genotype-1b HCV who received daclatasvir plus asunaprevir therapy for more than 4 weeks. Serum concentrations of both the DAAs were measured at 4 weeks after the initiation of therapy., Result: Liver injuries including serum AST and/or ALT level elevation to 150 U/L or over were found in 34 patients (12.2%). Multivariate logistic regression analysis identified serum asunaprevir concentrations as being significantly associated with developing liver injury, with an odds ratio of 1.046 (95% confidence interval 1.011-1.082, p<0.05). Serum asunaprevir concentrations showed correlation with the extent of liver fibrosis, estimated by peripheral platelets counts and serum albumin levels and baseline and FIB4 index and serum Mac-2 binding protein glycosylation isomer (M2BPGi) levels at 4 weeks of the therapy; the concentrations were significantly higher among patients showing 3.0 or more of M2BPGi levels than among those with the levels less than 3.0; on the other hand, no such correlation/difference was found in serum daclatasvir concentrations., Conclusion: High serum concentrations of serum asunaprevir, which were associated with the extent of liver fibrosis, appear to provoke the occurrence of liver injury in patients with genotype-1b HCV receiving combined daclatasvir plus asunaprevir therapy., Competing Interests: SM has received patent royalties from SRL Inc., has received speaking fees or hon-oraria from AbbVie GK, Ajinomoto Pharmaceuticals Co. Ltd., Bristol Myers Squibb Co., Gilead Sciences Inc., MSD K.K., Sumitomo Dainippon Pharma Co., Toray Medical Co. Ltd., has received research grants from A2 Healthcare Co., AbbVie GK, Bristol Myers Squibb Co., Chugai Pharma-ceutical Co. Ltd., EA Pharma Co. Ltd., Mitsubishi Tanabe Pharma Co., MSD K.K., Sumitomo Dainippon Pharma Co., Toray Medical Co. Ltd. YU has received research grants from AbbVie GK. This does not alter our adherence to PLOS ONE policies on sharing data and materials.