Search

Because of its greater binding affinity and longer half-life than native glucagon-like peptide-1 (GLP-1), the GLP-1 receptor agonist lixisenatide is commonly used to treat type 2 diabetes mellitus. This study aimed to establish a simple and robust liquid chromatography–tandem mass spectrometry (LC–MS/MS) approach for lixisenatide for in vivo pharmacokinetic investigation. Methanol-based protein precipitation with formic acid was exploited for plasma sample extraction, using esomeprazole as the internal standard. Gradient elution with 0.1% formic acid in distilled water and acetonitrile was utilized for chromatographic separation. Mass spectrometry was used to monitor the MRM transition at m/z 810.8 → 129.2 for lixisenatide. In rat plasma, lixisenatide had a lower limit of quantification of 10 ng/mL. The LC–MS/MS was applied to describe the pharmacokinetics of lixisenatide in rats following intravenous and subcutaneous dosing. The average half-life of lixisenatide was 0.37 ± 0.06 h after intravenous injection. The estimated subcutaneous bioavailability of lixisenatide was 2.17%. This LC–MS/MS analysis might be relevant in future research to create novel dosage formulations of lixisenatide and other GLP-1 receptor agonists with optimal therapeutic effectiveness. [ABSTRACT FROM AUTHOR]

Hexamethylenetetramine, an aldehyde-releasing agent, is used as a preservative in various food, cosmetics, and medical treatments, such as a treatment for urinary tract infections. It has been reported to be allergenic on contact with the skin, with the additional possibility of causing toxicity once absorbed systemically. Despite its potential toxicity, there are no reports on the in vivo bioavailability of hexamethylenetetramine following oral or dermal administration. In this study, we developed a new simple and sensitive LC–MS/MS method for the determination of hexamethylenetetramine in plasma and applied this method to characterize the toxicokinetics. The developed assay had a sufficient specificity and sensitivity for toxicokinetic characterization, and its accuracy and precision were verified. Following iv injection, the plasma concentration of hexamethylenetetramine showed mono exponential decay, with an elimination half-life of about 1.3 h. Following oral administration, the Tmax reached an average of 0.47 h and bioavailability was estimated as 89.93%. After percutaneous administration, it reached Cmax on average at 2.9–3.6 h. Although the absorption rate was relatively slow, its average bioavailability was calculated as 77.19–78.91%. Overall, most of the orally and percutaneously administered hexamethylenetetramine was absorbed into systemic circulation. The derived results in this study are expected to be utilized as the scientific evidence for further toxicokinetic study and risk assessment. [ABSTRACT FROM AUTHOR]

Nafamostat, a synthetic serine protease inhibitor, has been used for the treatment of inflammatory diseases such as pancreatitis. Recently, an increasing number of studies have shown the promising antiviral effects of nafamostat for the treatment of coronavirus disease-19 (COVID-19). This study aimed to develop a novel liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis and to characterize the pharmacokinetics of nafamostat in rats. Nafamostat in the rat plasma was extracted by solid phase extraction, and 13C6-nafamostat was used as an internal standard. The quantification limit of nafamostat in the rat plasma was 0.5 ng/mL. The LC-MS/MS method was fully validated and applied to characterize the pharmacokinetics of nafamostat in rats. Following intravenous injection (2 mg/kg), nafamostat in the plasma showed a multiexponential decline with an average elimination half-life (t1/2) of 1.39 h. Following oral administration of nafamostat solutions (20 mg/kg) in 10% dimethyl sulfoxide (DMSO) and in 10% DMSO with 10% Tween 80, nafamostat was rapidly absorbed, and the average oral bioavailability was 0.95% and 1.59%, respectively. The LC-MS/MS method and the pharmacokinetic information of nafamostat could be helpful for the further preclinical and clinical studies of nafamostat. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • LC–MS/MS analysis for simultaneous determination of 5 amino acids was developed. • The assay was fully validated and applied to in vivo studies in rats and dogs. • Proline, hydroxyproline, and citrulline levels were reduced by aceclofenac doses. • The assay may be useful to monitor changes of the amino acid levels as biomarkers. Abstract Although major adverse effects associated with nonsteroidal anti-inflammatory drugs (NSAIDs) are gastric injury, assessment of NSAIDs-induced gastrointestinal adverse effects is mostly dependent on endoscopy due to the lack of plasma biomarkers. Several amino acids associated with collagenase activity and gastric mucosal mass have been suggested as plasma biomarker candidates for gastric injury. Therefore, this study aimed to develop a liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for the plasma biomarker candidates, i.e., acetylcarnitine, proline, hydroxyproline, citrulline, and arginine and evaluate their potential as a biomarker for NSAIDs-induced gastric injury. The method utilized simple protein precipitation with methanol and D 4 -citrulline as an internal standard (IS). The assay resulted in the lower limit of quantification (LLOQ) of 0.1 μg/mL for acetylcarnitine and 1 μg/mL for proline, hydroxyproline, citrulline, and arginine in the surrogate blank plasma. The intra- and inter-day accuracy ranged 82.5–111.2% for acetylcarnitine, 95.4–103.3% for proline, 98.9–106.4% for hydroxyproline, 99.5–103.5% for citrulline, and 87.4–105.3% for arginine. The precision was within 6.17%, 3.63%, 6.20%, 6.31%, and 6.17% for acetylcarnitine, proline, hydroxyproline, citrulline, and arginine, respectively. The developed assay was successfully applied to monitor the changes of the plasma levels of the five amino acids in rats and Beagle dogs following repeated oral administrations of aceclofenac. In rats, plasma concentrations of proline, hydroxyproline, and citrulline were significantly reduced after 4 days of aceclofenac administration compared to the control group. In dogs, plasma concentrations of proline and citrulline were significantly decreased after 7 days of aceclofenac administration compared to those obtained after the first aceclofenac administration. These data indicate that plasma levels of proline, hydroxyproline, and citrulline may be used as quantitative biomarkers of NSAIDs-induced gastric damage. The present assay could also be utilized to monitor the changes of these amino acids as potential indicators for various physiological and pathophysiological conditions. [ABSTRACT FROM AUTHOR]

Acrylamide (AA) is a heat-generated food toxicant formed when starchy foods are fried or baked. This study describes a simple and sensitive liquid chromatography–tandem mass spectrometry assay for the simultaneous quantification of AA and its active metabolite, glycidamide (GA) in rat plasma, urine, and 14 different tissues. The assay utilized a simple method of protein precipitation and achieved a lower limit of quantification of 5, 10 and 25 ng/mL of AA and 10, 20 and 100 ng/mL of GA for plasma, tissues and urine, respectively. The assay was fully validated to demonstrate the linearity, sensitivity, accuracy, precision, process recovery, and stability using matrix matched quality control samples. The mean intra- and inter-day assay accuracy was 91.6–110% for AA and 92.0–109% for GA, and the mean intra- and inter-day assay precisions were ≤10.9% for AA and ≤8.60% for GA. The developed method was successfully applied to a pharmacokinetic study of AA and GA following intravenous and oral administration of AA in rats. Tissue distribution characteristics of AA and GA were also determined under steady-state conditions. [ABSTRACT FROM AUTHOR]

Abstract: The utility of an LC–MS/MS assay for nitrite determination in studying l-arginine (ARG) cellular action was examined in vitro. EA.hy926 human endothelial cells or cellular fractions (membrane and cytosol) were exposed to 0–500μM of 15N4-ARG for 2h. 14N-nitrite and 15N-nitrite in the cell lysate and in the incubation medium were derivatized with 2,3-diaminonaphthalene (DAN) to form 14N- and 15N-naphthotriazole (i.e., 14N-NAT and 15N-NAT). Peak responses of 14N-NAT and 15N-NAT were analyzed by LC–MS/MS with 1H-naphth[2,3-d]imidazole as an internal standard. The calibration curves of DAN-derivatized 14N-NAT and 15N-NAT from 14N-nitrite and 15N-nitrite were linear. Intra- and inter-day variability of the quantification was below 14.2% in quality control samples. Following incubation of EA.hy926 cells with 15N4-ARG, saturable increases of 15N-nitrite accumulation with increasing 15N4-ARG exposure were observed clearly. This increase however could not be detected by the classical fluorescence method, nor were changes in 14N-nitrite level observed. When cellular fractions were exposed to 15N4-ARG, 15N-nitrite formation was only observed in the membrane fragments. The sensitive and selective LC–MS/MS method reported here can be applied to quantify accumulated nitrite levels in human endothelial cells. The selectivity of this stable-isotope labeled LC–MS/MS method offers an advantage over other traditional methods for elucidating cellular ARG action when its stable isotope is employed as a substrate. [Copyright &y& Elsevier]

Abstract: Purpose: l-Arginine (ARG) is converted to nitric oxide (NO) and l-citrulline (CIT) by endothelial nitric oxide synthase which is competitively inhibited by asymmetric dimethylarginine (ADMA). We have developed a liquid chromatography–mass spectrometric method for the simultaneous determination of endogenous ARG, labeled ARG (15N4-ARG), CIT, ADMA, and its inactive isomer, symmetric dimethylarginine (SDMA) in biological samples. Methods: Concentrations of unlabeled ARG, 15N4-ARG, CIT, ADMA, and SDMA in EA.hy926 human endothelial cell lysate, cell incubation media, rat plasma or rat urine were measured by hydrophilic-interaction liquid chromatography electrospray tandem mass spectrometry. 13C6-ARG, D4-CIT and D7-ADMA were used as internal standards for ARG and 15N4-ARG, CIT, and dimethylarginines, respectively. Results: The calibration curves of ARG, 15N4-ARG, CIT, ADMA, and SDMA were linear and independent of several sample matrices. Intra- and inter-day variabilities for the quantification of all the compounds were below 15% in quality control samples. Application of this method to determine the uptake as well as efflux of these compounds was illustrated through in vitro cell study by exposing human endothelial cells to 15N4-ARG, which allowed the observation of generation of 15N3-CIT and 15N3-ARG in the cell lyate. Use of these isotopes adds insights into the cellular handling of endogenous vs. exogenous ARG. Application of this method for rat plasma and rat urine assays was demonstrated after ARG oral supplementation in rats. Conclusion: An LC–MS/MS method was developed to quantify 6 ARG-related compounds simultaneously, utilizing 3 separate internal standards. This assay allows concurrent monitoring of uptake, efflux and metabolic processes when isotope-labeled ARG and CIT are measured, and can be applied for determination of these compounds in rat plasma and rat urine. [Copyright &y& Elsevier]

Desoxo-narchinol A is one of the major active constituents from Nardostachys jatamansi, which has been reported to possess various pharmacological activities, including anti-inflammatory, antioxidant, and anticonvulsant activity. A simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of desoxo-narchinol A in two different biological matrices, i.e., rat plasma and mouse plasma, using sildenafil as an internal standard (IS). The method involved simple protein precipitation with acetonitrile and the analyte was separated by gradient elution using 100% acetonitrile and 0.1% formic acid in water as a mobile phase. The MS detection was performed with a turbo electrospray in positive ion mode. The lower limit of quantification was 10 ng/mL in both rat and mouse plasma. Intra- and inter-day accuracies were in the ranges of 97.23–104.54% in the rat plasma and 95.90–110.11% in the mouse plasma. The precisions were within 8.65% and 6.46% in the rat and mouse plasma, respectively. The method was applied to examine the pharmacokinetics of desoxo-narchinol A, and the oral bioavailability of desoxo-narchinol A was 18.1% in rats and 28.4% in mice. The present results may be useful for further preclinical and clinical studies of desoxo-narchinol A. [ABSTRACT FROM AUTHOR]

• Novel LC-MS/MS assay for the determination of lifitegrast in rabbit plasma and ocular tisses were developed. • The assay accuracy, precision, specificity, linearity, and stability were validated. • The 3.26% of dosed lifitegrast was absorbed into blood. • After ophthalmic administration, lifitegrast was significantly distributed in conjunctiva and cornea. Lifitegrast, a lymphocyte function-associated antigen 1 antagonist, was approved by the FDA for the treatment of dry eye disease. Cornea and conjunctiva have been reported to be the sites of action of lifitegrast. To investigate the pharmacokinetics of lifitegrast, a sensitive analytical method for the determination of lifitegrast in various biological matrices such as plasma and ocular tissues is required. However, only limited information about the analytical method for lifitegrast in biological samples is available. In the present study, we aimed to develop a new liquid chromatography-tandem mass spectrometry method for the determination of lifitegrast in rabbit plasma, cornea, conjunctiva, and sclera. Lifitegrast-d 6 was used as an internal standard (IS). To prepare the biological samples, protein precipitation using acetonitrile was utilized. Analytes were separated from endogenous interferences on an Atlantis dC18 (5 µm, 2.1 × 150 mm), and a mixture of 0.1 % formic acid and acetonitrile was used as the mobile phase. The mass transition of precursor to product ion was monitored at 615.2 → 145.0 for lifitegrast and 621.2 → 145.1 for IS. The calibration curves were linear over the concentration range from 2 to 500 ng/mL for plasma and 5 to 500 ng/mL in ocular tissue homogenates. Intra- and inter-day accuracy ranged from 95.76 to 106.80 % in the plasma and 94.42 to 112.80 % in the ocular tissues. Precision was within 8.56 % in the plasma and 9.72 % in the ocular tissues. The short-term, long-term, auto-sampler, and freeze–thaw stabilities of lifitegrast were validated. The developed method was applied to a pharmacokinetic study of lifitegrast in rabbits. Following ophthalmic administration, only 3.26 % of administered lifitegrast was absorbed into the systemic circulation. Peak tissue concentrations were observed at 0.5 h after dosing, and topically administered lifitegrast was mainly distributed in the cornea and conjunctiva. The finding of this study is expected to be used in further pharmacokinetic studies and formulation development. [ABSTRACT FROM AUTHOR]

• Novel LC-MS/MS to determine semaglutide was developed for pharmacokinetic studies. • The method has superior sensitivity and fully validated in the plasma and brain. • Subcutaneous bioavailability of semaglutide was 76.65–82.85 % in rats. • Semaglutide is significantly distributed in hypothalamus among other brain regions. Semaglutide, one of the most potent glucagon-like peptide (GLP)-1 analogs, has widely been used to treat type II diabetes mellitus and obesity. Recent studies have shown that semaglutide also works on the brain, suggesting its potential utility for various diseases, including Parkinson's disease and Alzheimer's disease. This study aimed to develop a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of semaglutide in both plasma and brain to characterize the pharmacokinetics and brain distribution in rats. Semaglutide was extracted by simple protein precipitation with methanol from plasma and by solid phase extraction from brain tissue. Liraglutide was used as an internal standard. Gradient elution profiles with mobile phases comprising 0.1 % formic acid in water and acetonitrile were used for chromatographic separation. The lower limit of quantification (LLOQ) of the LC-MS/MS assay was 0.5 ng/mL for both rat plasma and brain. Intra- and inter-day accuracy ranged 89.20–109.50 % in the plasma and 92.00–105.00 % in the brain. Precision was within 8.92 % in the plasma and 7.94 % in the brain. Sprague-Dawley rats were given semaglutide by intravenous (IV, 0.02 mg/kg) and subcutaneous (SC, 0.1 and 0.2 mg/kg) injection. Plasma concentrations of semaglutide showed a multi-exponential decline with an average half-life of 7.22–9.26 hr in rats. The subcutaneous bioavailability of semaglutide was 76.65–82.85 %. The brain tissue to plasma partition coefficient (K p) value of semaglutide was estimated as <0.01. Among the different regions of the brain, semaglutide concentrations were significantly higher in the hypothalamus. The analytical method and pharmacokinetic information may be helpful toward a better understanding of the effect of semaglutide in the brain and further development of GLP-1 analogs for various brain diseases. [ABSTRACT FROM AUTHOR]