Investigation of pharmacokinetic properties of a PEGylated bilirubin nanoparticle in male Sprague-Dawley rats using liquid chromatography-quadrupole time-of-flight mass spectrometry

Polyethylene glycol (PEG) was introduced into synthetic bilirubin 3α and a PEGylated bilirubin 3α nanoparticle (BX-001N, Brixelle®) was developed for the first time.An in vitro microsomal stability study, in vivo PK studies with intravenous bolus (IV) and subcutaneous injection (SC), and a semi-mass balance study of BX-001N were investigated to evaluate its pharmacokinetic (PK) properties in male Sprague-Dawley (SD) rats using developed liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-qTOF/MS).Following IV administration at 10 or 30 mg/kg, BX-001N showed very low clearance (0.33-0.67 mL/min/kg) with predominant distribution in the vascular system (Vd = 51.73-83.02 mL/kg). BX-001N was also very stable in vitro liver microsomal stability study.Following SC administration at 10 or 30 mg/kg, the bioavailability of BX-001N in plasma at 10 mg/kg was around 43% and showed the less dose-proportionality at 30 mg/kg dose.BX-001N was mainly excreted via the urinary pathway (86.59-92.99% of total amount of parent drug in excreta; urine and faeces) not via the biliary one.

High-Throughput Acoustic Ejection Mass Spectrometry with Adjustable Signal Durations

High-throughput mass spectrometry (MS) has witnessed rapid advancements and has found extensive applications across various disciplines. It enables the fast and accurate analysis of large sample sets, delivering a 10-fold or greater enhancement in analytical throughput when compared to conventional LC-MS methods. However, the signal duration in these high-throughput MS technologies is typically confined to a narrow range, presenting challenges for workflows demanding prolonged signal durations. In this study, we introduce a method that enables precise modulation of the signal duration on an acoustic ejection mass spectrometry (AEMS) system while ensuring high signal reproducibility. This flexibility allows for simultaneous and precise analysis of a significantly greater number of MS/MS transitions in high-throughput MS environments. Additionally, it offers a unique approach for parameter optimization and method development with minimal sample volume requirements. This advancement enhances the efficiency of MS-based analyses across diverse applications and facilitates broader utilization of MS technologies in high-throughput settings, including data-dependent acquisition (DDA) and data-independent acquisition (DIA).

Quantitative LC-MS/MS. 1. Impact of Points across a Peak on the Accuracy and Precision of Peak Area Measurements

The number of points across a chromatographic peak has long been recognized as a key determinant of the accuracy and precision of the measured peak area. In LC-MS-based quantitation experiments in drug discovery and development, the "rule-of-thumb" has been to use 15 or more points. This "rule" is based on the literature describing chromatographic methods where the goal was to achieve the lowest possible imprecision in the measurements, especially when unknown analytes are being detected. Restricting methods to the requirement of at least 15 points across a peak can be detrimental to the development methods that fully optimize the signal-to-noise ratio for the assay using longer dwell times and/or transition summing. This study aims to show that 7 points across the peak for peaks that are 9 s or less wide provide more than sufficient accuracy and precision for drug quantitation studies. Data from simulated Gaussian curves using a sampling interval of 7 points across the peak gave peak area calculations within 1% of the expected total peak area using the Trapezoidal and Riemann rules and 0.6% for the Simpson rule. Low and high concentration samples (n = 5) were assayed using three different LC methods on three different days on two different instruments (API5000 and API5500). The difference in peak area (%ΔPA) and relative standard deviation of the peak areas (%RSD) was less than ∼5%. No significant difference was observed from the data that were obtained from different sampling intervals, different peak widths, different days, different peak sizes, and different instruments. Three core analytical runs were performed on three different days. In each core run, the lower limit of quantitation (LLOQ, n = 5), low quality control (LQC, n = 5), middle quality control (MQC, n = 5), and high-quality control samples (HQC, n = 5) were processed and run simultaneously with a standard curve. The range of the intra- and interday accuracy and precision for 3 core runs was 98.0-105% and 0.9-3.0% for 7 data points and 97.5-105% and 0.8-4.3% for 17 data points, respectively. No significant difference was observed for the different sampling intervals. The results show a sampling interval of 7 points for peaks up to 9 s wide is sufficient to define a peak accurately and precisely for drug quantitation studies in drug discovery and development.

Evaluation of In Vivo Prepared Albumin-Drug Conjugate Using Immunoprecipitation Linked LC-MS Assay and Its Application to Mouse Pharmacokinetic Study

There have been many attempts in pharmaceutical industries and academia to improve the pharmacokinetic characteristics of anti-tumor small-molecule drugs by conjugating them with large molecules, such as monoclonal antibodies, called ADCs. In this context, albumin, one of the most abundant proteins in the blood, has also been proposed as a large molecule to be conjugated with anti-cancer small-molecule drugs. The half-life of albumin is 3 weeks in humans, and its distribution to tumors is higher than in normal tissues. However, few studies have been conducted for the in vivo prepared albumin-drug conjugates, possibly due to the lack of robust bioanalytical methods, which are critical for evaluating the ADME/PK properties of in vivo prepared albumin-drug conjugates. In this study, we developed a bioanalytical method of the albumin-conjugated MAC glucuronide phenol linked SN-38 ((2S,3S,4S,5R,6S)-6-(4-(((((((S)-4,11-diethyl-4-hydroxy-3,14-dioxo-3,4,12,14-tetrahydro-1H-pyrano [3',4':6,7] indolizino [1,2-b] quinolin-9-yl)oxy)methyl)(2 (methylsulfonyl)ethyl)carbamoyl)oxy)methyl)-2-(2-(3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)-N-methylpropanamido)acetamido)phenoxy)-3,4,5-trihydroxytetra-hydro-2H-pyran-2-carboxylic acid) as a proof-of-concept. This method is based on immunoprecipitation using magnetic beads and the quantification of albumin-conjugated drug concentration using LC-qTOF/MS in mouse plasma. Finally, the developed method was applied to the in vivo intravenous (IV) mouse pharmacokinetic study of MAC glucuronide phenol-linked SN-38.

Investigation of In Vitro and In Vivo Metabolism of α-Amanitin in Rats Using Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometric Method

The purpose of this study is to investigate the difference of in vitro-in vivo correlation of α-amanitin from clearance perspectives as well as to explore the possibility of extra-hepatic metabolism of α-amanitin. First, a liquid chromatography-quadrupole-time-of-flight-mass spectrometric (LC-qTOF-MS) method for α-amanitin in rat plasma was developed and applied to evaluate the in vitro liver microsomal metabolic stability using rat and human liver microsomes and the pharmacokinetics of α-amanitin in rat. The predicted hepatic clearance of α-amanitin in rat liver microsomes was quite low (5.05 mL/min/kg), whereas its in vivo clearance in rat (14.0 mL/min/kg) was close to the borderline between low and moderate clearance. To find out the difference between in vitro and in vivo metabolism, in vitro and in vivo metabolite identification was also conducted. No significant metabolites were identified from the in vivo rat plasma and the major circulating entity in rat plasma was α-amanitin itself. No reactive metabolites such as GSH-adducts were detected either. A glucuronide metabolite was newly identified from the in vitro liver microsomes samples with a trace level. A semi-mass balance study was also conducted to understand the in vivo elimination pathway of α-amanitin and it showed that most α-amanitin was mainly eliminated in urine as intact which implies some unknown transporters in kidney might play a role in the elimination of α-amanitin in rat in vivo. Further studies with transporters in the kidney would be warranted to figure out the in vivo clearance mechanism of α-amanitin.

Enhanced drug delivery by a prodrug approach effectively relieves neuroinflammation in mice

AIMS

Neuroinflammation is a prominent hallmark in several neurodegenerative diseases (NDs). Halting neuroinflammation can slow down the progression of NDs. Improving the efficacy of clinically available non-steroidal anti-inflammatory drugs (NSAIDs) is a promising approach that may lead to fast-track and effective disease-modifying therapies for NDs. Here, we aimed to utilize the L-type amino acid transporter 1 (LAT1) to improve the efficacy of salicylic acid as an example of an NSAID prodrug, for which brain uptake and intracellular localization have been reported earlier.

MAIN METHODS

Firstly, we confirmed the improved LAT1 utilization of the salicylic acid prodrug (SA-AA) in freshly isolated primary mouse microglial cells. Secondly, we performed behavioural rotarod, open field, and four-limb hanging tests in mice, and a whole-brain proteome analysis.

KEY FINDINGS

The SA-AA prodrug alleviated the lipopolysaccharide (LPS)-induced inflammation in the rotarod and hanging tests. The proteome analysis indicated decreased neuroinflammation at the molecular level. We identified 399 proteins linked to neuroinflammation out of 7416 proteins detected in the mouse brain. Among them, Gps2, Vamp8, Slc6a3, Slc18a2, Slc5a7, Rgs9, Lrrc1, Ppp1r1b, Gnal, and Adcy5/6 were associated with the drug's effects. The SA-AA prodrug attenuated the LPS-induced neuroinflammation through the regulation of critical pathways of neuroinflammation such as the cellular response to stress and transmission across chemical synapses.

SIGNIFICANCE

The efficacy of NSAIDs can be improved via the utilization of LAT1 and repurposed for the treatment of neuroinflammation. This improved brain delivery and microglia localisation can be applied to other inflammatory modulators to achieve effective and targeted CNS therapies.

Quantitative Analysis of Daporinad (FK866) and Its In Vitro and In Vivo Metabolite Identification Using Liquid Chromatography-Quadrupole-Time-of-Flight Mass Spectrometry

Daporinad (FK866) is one of the highly specific inhibitors of nicotinamide phosphoribosyl transferase (NAMPT) and known to have its unique mechanism of action that induces the tumor cell apoptosis. In this study, a simple and sensitive liquid chromatography–quadrupole-time-of-flight–mass spectrometric (LC-qTOF-MS) assay has been developed for the evaluation of drug metabolism and pharmacokinetics (DMPK) properties of Daporinad in mice. A simple protein precipitation method using acetonitrile (ACN) was used for the sample preparation and the pre-treated samples were separated by a C18 column. The calibration curve was evaluated in the range of 1.02~2220 ng/mL and the quadratic regression (weighted 1/concentration²) was used for the best fit of the curve with a correlation coefficient ≥ 0.99. The qualification run met the acceptance criteria of ±25% accuracy and precision values for QC samples. The dilution integrity was verified for 5, 10 and 30-fold dilution and the accuracy and precision of the dilution QC samples were also satisfactory within ±25% of the nominal values. The stability results indicated that Daporinad was stable for the following conditions: short-term (4 h), long-term (2 weeks), freeze/thaw (three cycles). This qualified method was successfully applied to intravenous (IV) pharmacokinetic (PK) studies of Daporinad in mice at doses of 5, 10 and 30 mg/kg. As a result, it showed a linear PK tendency in the dose range from 5 to 10 mg/kg, but a non-linear PK tendency in the dose of 30 mg/kg. In addition, in vitro and in vivo metabolite identification (Met ID) studies were conducted to understand the PK properties of Daporinad and the results showed that a total of 25 metabolites were identified as ten different types of metabolism in our experimental conditions. In conclusion, the LC-qTOF-MS assay was successfully developed for the quantification of Daporinad in mouse plasma as well as for its in vitro and in vivo metabolite identification.

Improving LC/MS/MS-based bioanalytical method performance and sensitivity via a hybrid surface barrier to mitigate analyte - Metal surface interactions

The accurate determination of the pharmacokinetics (PK) of a candidate drug molecule is critical in both drug discovery and development. Over the last 30 years, the sensitivity and selectivity of LC/MS has resulted in it being established as the technology of choice for these studies. However, unwanted chemical interactions between analyte(s) and the metal components in a chromatography system can result in poor peak shape and reduction in signal response, which can adversely affect the analysis of low concentrations of drugs and their metabolites in biological samples. This study evaluated the benefits of employing an inert hybrid surface technology (HST) applied to the metallic components in the LC flow path, column frits and column wall to mitigate these interactions. The results obtained were compared with that of an identical conventional LC for the bioanalysis of two steroid phosphate drugs (dexamethasone phosphate and hydrocortisone phosphate) and an epidermal growth factor receptor (EGFR) inhibitor (gefitinib) in human plasma. The results showed that for the two steroid phosphates, the peak width was reduced by 20%, peak tailing factors reduced by up to 30% and the assay sensitivity improved by factors of 7.5 and 10. This resulted in a significant improvement in the limit of detection. The new LC system also improved the reproducibility of peak integration for gefitinib, thereby reducing assay coefficients of variation (%CV) from greater than 10% to less than 5% at the lower limit of quantification.

A targeted ultra performance liquid chromatography - Tandem mass spectrometric assay for tyrosine and metabolites in urine and plasma: Application to the effects of antibiotics on mice

Tyrosine plays a key role in mammalian biochemistry and defects in its metabolism (e.g., tyrosinemia, alkaptonuria etc.) have significant adverse consequences for those affected if left untreated. In addition, gut bacterially-derived p-cresol and its metabolites are of interest as a result of various effects on host xenobiotic metabolism. A fit-for-purpose quantitative ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) assay was developed to target and quantify tyrosine and eleven metabolites in urine and plasma. Dansylation, using dansyl chloride, was used to improve chromatographic and mass spectral properties for tyrosine and nine phenolic metabolites, with detection using positive electrospray ionisation (ESI). The sulfate and glucuronide conjugates of p-cresol, where the phenol group was blocked, were quantified intact, using negative ESI via polarity switching during the same run. Sample preparation for urine and plasma involved deproteinization by solvent precipitation (of acetonitrile:isopropyl alcohol (1:1 v/v)) followed by in situ dansylation in 96 well plates. To minimize sample and solvent usage, and maximize sensitivity, analysis was performed using microbore reversed-phase gradient UPLC on a C8 phase with a 7.5 min. cycle time. The coefficients of variation obtained were <15%, with lower limits of quantification ranging from 5 to 250 nM depending upon the analyte. The method was applied to plasma and urine samples obtained from mice placed on a high tyrosine diet with one subgroup of animals subsequently receiving antibiotics to suppress the gut microbiota. Whilst plasma profiles were largely unaffected by antibiotic treatment clear reductions in the amount of p-cresol sulfate and p-cresol glucuronide excreted in the urine were observed for these mice.

A Surrogate Matrix-Based Approach Toward Multiplexed Quantitation of an sGC Stimulator and cGMP in Ocular Tissue and Plasma

A liquid chromatography-tandem mass spectrometry assay was developed and qualified for the multiplexed quantitation of a small molecule stimulator of soluble guanylate cyclase (sGC) and its target engagement biomarker, 3',5'-cyclic guanosine monophosphate (cGMP), in ocular tissues and plasma from a single surrogate matrix calibration curve. A surrogate matrix approach was used in this assay due to the limited quantities of blank ocular matrices in a discovery research setting. After optimization, the assay showed high accuracy, precision, and recovery as well as parallelism between the surrogate matrix and the biological matrices (rabbit plasma, vitreous, and retina-choroid). This assay provided pharmacokinetic and target engagement data after intravitreal administration of the sGC stimulator. The nitric oxide-sGC-cGMP pathway is a potential target to address glaucoma. Increasing sGC-mediated production of cGMP could improve aqueous humor outflow and ocular blood flow. The sGC stimulator showed dose-dependent exposure in rabbit vitreous, retina-choroid, and plasma. The cGMP exhibited a delayed yet sustained increase in vitreous humor but not retina-choroid. Multiplexed measurement of both pharmacokinetic and target engagement analytes reduced animal usage and provided improved context for interpreting PK and PD relationships.

The analysis of acetaminophen (paracetamol) and seven metabolites in rat, pig and human plasma by U(H)PLC-MS

A U(H)PLC-MS/MS method is described for the analysis of acetaminophen and its sulphate, glucuronide, glutathione, cysteinyl and N-acetylcysteinyl metabolites in plasma using stable isotope-labeled internal standards. P-Aminophenol glucuronide and 3-methoxyacetaminophen were monitored and semi-quantified using external standards. The assay takes 7.5 min/sample, requires only 5 μl of plasma and involves minimal sample preparation. The method was validated for rat plasma and cross validated for human and pig plasma and mouse serum. LOQ in plasma for these analytes were 0.44 μg/ml (APAP-C), 0.58 μg/ml (APAP-SG), 0.84 μg/ml (APAP-NAC), 2.75 μg/ml (APAP-S), 3.00 μg/ml (APAP-G) and 16 μg/ml (APAP). Application of the method is illustrated by the analysis of plasma following oral administration of APAP to male Han Wistar rats.

In Vitro, In Silico, and In Vivo Assessments of Pharmacokinetic Properties of ZM241385

Parkinson’s disease is one of the most common neurodegenerative diseases. Adenosine regulates the response to other neurotransmitters in the brain regions related to motor function. In the several subtypes of adenosine receptors, especially, adenosine 2A receptors (A_2ARs) are involved in neurodegenerative conditions. ZM241385 is one of the selective non-xanthine A2AR antagonists with high affinity in the nanomolar range. This study describes the in vitro and in vivo pharmacokinetic properties of ZM241385 in rats. A liquid chromatography-quadrupole time-of-flight mass spectrometric (LC-qToF MS) method was developed for the determination of ZM241385 in rat plasma. In vivo IV administration studies showed that ZM241385 was rapidly eliminated in rats. However, the result of in vitro metabolic stability studies showed that ZM241385 had moderate clearance, suggesting that there is an extra clearance pathway in addition to hepatic clearance. In addition, in vivo PO administration studies demonstrated that ZM241385 had low exposure in rats. The results of semi-mass balance studies and the in silico PBPK modeling studies suggested that the low bioavailability of ZM241385 after oral administration in rats was due to the metabolism and by liver, kidney, and gut.

Addition of Optimized Bovine Serum Albumin Level in a High-Throughput Caco-2 Assay Enabled Accurate Permeability Assessment for Lipophilic Compounds

The Caco-2 permeability assay is a well-accepted in vitro model to evaluate compounds’ potential for oral absorption at early discovery. However, for many lipophilic compounds, no meaningful Caco-2 data could be generated due to their low solubility in assay buffer and/or poor recovery from the assay. In our previous study, we reported an organic catch approach to improve compound recovery. To further reduce compound loss and increase solubility in aqueous buffer, we explored the addition of bovine serum albumin (BSA). However, in contrast to the commonly used BSA level at 4%, a lower level of BSA was selected in an effort to minimize the potential risk of missing the identification of efflux substrates, and to avoid the extensive sample cleanup needed for 4% BSA. Through a systematic evaluation, it was found that 0.5% BSA was effective in enhancing compound solubility and reducing nonspecific binding, which allowed reliable assessment of the permeability and efflux potential for lipophilic compounds. Also, with an optimized sample handling process, no extra sample cleanup was required before liquid chromatography–mass spectrometry (LC-MS) analysis. The implementation of this assay has enabled accurate permeability assessment for compounds that had poor solubility and/or poor mass balance under the non-BSA assay conditions.

Assessment of the clinical cardiac drug-drug interaction associated with the combination of hepatitis C virus nucleotide inhibitors and amiodarone in guinea pigs and rhesus monkeys

In 2015, European and U.S. health agencies issued warning letters in response to 9 reported clinical cases of severe bradycardia/bradyarrhythmia in hepatitis C virus (HCV)-infected patients treated with sofosbuvir (SOF) in combination with other direct acting antivirals (DAAs) and the antiarrhythmic drug, amiodarone (AMIO). We utilized preclinical in vivo models to better understand this cardiac effect, the potential pharmacological mechanism(s), and to identify a clinically translatable model to assess the drug-drug interaction (DDI) cardiac risk of current and future HCV inhibitors. An anesthetized guinea pig model was used to elicit a SOF+AMIO-dependent bradycardia. Detailed cardiac electrophysiological studies in this species revealed SOF+AMIO-dependent selective nodal dysfunction, with initial, larger effects on the sinoatrial node. Further studies in conscious, rhesus monkeys revealed an emergent bradycardia and bradyarrhythmia in 3 of 4 monkeys administered SOF+AMIO, effects not observed with either agent alone. Morever, bradycardia and bradyarrhythmia were not observed in rhesus monkeys when intravenous infusion of MK-3682 was completed after AMIO pretreatment.

CONCLUSIONS

These are the first preclinical in vivo experiments reported to replicate the severe clinical SOF+AMIO cardiac DDI and provide potential in vivo mechanism of action. As such, these data provide a preclinical risk assessment paradigm, including a clinically relevant nonhuman primate model, with which to better understand cardiovascular DDI risk for this therapeutic class. Furthermore, these studies suggest that not all HCV DAAs and, in particular, not all HCV nonstructural protein 5B inhibitors may exhibit this cardiac DDI with amiodarone. Given the selective in vivo cardiac electrophysiological effect, these data enable targeted cellular/molecular mechanistic studies to more precisely identify cell types, receptors, and/or ion channels responsible for the clinical DDI. (Hepatology 2016;64:1430-1441).

Automated DBS microsampling, microscale automation and microflow LC–MS for therapeutic protein PK

Aim: Reduce animal usage for discovery-stage PK studies for biologics programs using microsampling-based approaches and microscale LC–MS. Methods & results: We report the development of an automated DBS-based serial microsampling approach for studying the PK of therapeutic proteins in mice. Automated sample preparation and microflow LC–MS were used to enable assay miniaturization and improve overall assay throughput. Serial sampling of mice was possible over the full 21-day study period with the first six time points over 24 h being collected using automated DBS sample collection. Overall, this approach demonstrated comparable data to a previous study using single mice per time point liquid samples while reducing animal and compound requirements by 14-fold. Conclusion: Reduction in animals and drug material is enabled by the use of automated serial DBS microsampling for mice studies in discovery-stage studies of protein therapeutics.