Development and validation of an HILIC/MS/MS method for determination of nusinersen in rabbit plasma.

A hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC/MS/MS) method was developed and validated for the quantitative analysis of the fully phosphorothioate modified oligonucleotide nusinersen. HILIC/MS/MS method is more robust and compatible with mass spectrometry than ion pair reversed-phase liquid chromatography-tandem mass spectrometry (IP-RP-LC/MS/MS). Various types and concentrations of additives and different pH of mobile phase affected the mass spectrometry response, chromatographic peak shape and retention of nusinersen. The optimized extraction method of nusinersen employs hydrophilic-lipophilic balance solid phase extraction, with a recovery of up to 80 %. Chromatographic quantification was performed using a gradient system on an amide column and the mobile phase consisted of ammonium acetate, acetonitrile and water in a certain proportion. The fully phosphorothioate modified nusinersen can obtain a high mass spectrometry response by providing greater peak symmetry and high ionization efficiency in a high-pH mobile phase. Moreover, the significant carry over interference was observed at the pH 6.3 of the mobile phase. Adjusting the pH value up to 10, and the carry over interference disappeared. The lower limit of quantitation of this developed HILIC/MS/MS assay was 30.0 ng/mL and the method was systematic methodology validated. This HILIC/MS/MS method provides an attractive and robust alternative for the quantitative analysis of nusinersen and was applied in the pharmacokinetic study of nusinersen in rabbits.

Development, validation and application of an ion-pair reversed-phase liquid chromatography-tandem mass spectrometry method for the quantification of nusinersen.

Background: The fully phosphorothioate-modified oligonucleotide (OGN) nusinersen has low ionization efficiency in the negative ion mode, resulting in a low mass spectrometry response. There have been no relevant reports on developing a LC-MS method for the determination of nusinersen by optimizing mobile phase composition. Materials & methods: Mobile phase additives comprised of 15 mM triethylamine/25 mM 1,1,1,3,3,3-hexafluoro-2-propanol with a pH of 9.6. Nusinersen was extracted from plasma using Oasis® HLB solid-phase extraction (Waters, MA, USA). Results & conclusion: By adjusting the pH of the mobile phase to 9.6 by optimizing the type and concentration of ion-pair reagents, a high mass spectrometry response was obtained. The developed method was applied to nusinersen and met the requirements for the pharmacokinetic study of nusinersen in rabbits.

Identification and validation of molecular subtype and prognostic signature for lung adenocarcinoma based on neutrophil extracellular traps.

Background: Neutrophil Extracellular Traps (NETs) are fibrous networks made of DNA-histone complexes and proteins protruded from activated neutrophils. Accumulating evidences have highlighted the vital role of NETs in tumor progression and diffusion. However, limited systematic studies regarding the role of NETs in LUAD have been performed. Methods: Differentially expressed NETs-related genes and their mutation landscape were identified with TCGA database. Consensus clustering analysis was performed to determine the NETs-related subtypes of LUAD. LASSO algorithm was employed to construct a prognostic signature. Moreover, GSE30219 and GSE31210 were used as independent validation. We also constructed a lncRNA-miRNA-mRNA regulatory axis with several miRNA and lncRNA databases. Results: Consensus clustering identified two NETs-related clusters in LUAD. High NETs score was correlated with a favorable overall survival, abundant immune cell infiltration, and high activity of immune response signal pathways. Six NET-related genes (G0S2, KCNJ15, S100A12, AKT2, CTSG, and HMGB1) with significant prognostic value were screened to develop a prognostic signature. LUAD patients with low-risk had a significantly favorable overall survival both in the training set and validation set. Moreover, NETs-related risk score and clinical stage could act as an independent prognostic factor for LUAD patients. Significant correlation was obtained between risk score and tumor immune microenvironment. We also identified lncRNA BCYRN1/miR-3664-5p/CTSG regulatory axis that may be involved in the progression of LUAD. Conclusion: We developed two molecular subtypes and a prognostic signature for LUAD based on NETs-related genes. This stratification could provide more evidences for estimating the prognosis and immunotherapy of LAUD patients.

Studying spatial drug distribution in golf ball-shaped microspheres to understand drug release.

Poly (lactic-co-glycolic acid) (PLGA) microspheres have been one of the most successful products for slow drug release. While distribution of drugs in microspheres might be a fundamental factor affecting drug release, it has been often overlooked. Indeed, very few studies are available on the distribution of drugs in microspheres with complex morphology like golf ball-shaped microspheres. In this paper, the distribution of rotigotine in golf ball-shaped microspheres (GSRM) was investigated by argon ion milling, combined with scanning electron microscopy and energy dispersive X-ray spectroscopy (AIM-SEM-EDS). Rotigotine in GSRM was clearly observed in two forms, respectively in an aggregated state and as a molecular dispersion. The distribution of palmitic acid in the microspheres (used as an additive to reduce burst release) was also demonstrated: 10% was found on the microspheres' surface while 90% separated from the polymer to form small particles inside the microspheres onto which rotigotine aggregated through hydrogen bonding interactions. In in-vitro release studies we observed that first the phase-separated palmitic acid/rotigotine particles dissolved and released the drug, followed by the release of the molecularly dispersed rotigotines by osmosis. We also found that rotigotine accelerated the degradation and reduced the glass transition temperature of PLGA, which played an important role as well in the release of the drug from GSRM. Finally, two linear Level A in vitro-in vivo correlations were established and validated, indicating that the in vitro release testing could be a meaningful predictor for the in vivo performance of GSRM. Our work demonstrates the importance of studying drug distribution in complex microspheres to understand drug release.

Liquid chromatography tandem mass spectrometry method for determination of fulvestrant in rat plasma and its application to pharmacokinetic studies of a novel fulvestrant microcrystal.

Fulvestrant ('Faslodex'), an estrogen receptor antagonist, is available for the treatment of advanced breast cancer. The oil-based vehicle of Faslodex can lead to various adverse effects. A novel fulvestrant microcrystal (aqueous suspension) was developed in this study to eliminate these adverse effects. A sensitive and robust liquid chromatography tandem mass spectrometry method was developed and validated for the determination of fulvestrant in rat plasma using supported-liquid extraction. The separation of fulvestrant was achieved on an Agilent SB-C18 column (2.1 × 50 mm, 3.5 µm) with isocratic elution using fulvestrant-d3 as internal standard. Mass spectrometric detection was conducted in negative multiple reaction monitoring mode. Ion transitions were at m/z 605.5 → 427.5 for fulvestrant and m/z 608.5 → 430.5 for fulvestrant-d3. The excellent linearity was demonstrated over the range 0.05-100.0 ng/ml (r2 = 0.99). The lower limit of quantitation was 0.05 ng/ml, which was superior to that reported in literature The method validation was evaluated by selectivity, accuracy, precision, recovery and matrix effect in agreement with the US Food and Drug Administration guidance. The method was successfully applied to a pharmacokinetic study of a novel fulvestrant microcrystal in rats after intramuscular administration. It revealed that the rate of absorption increases and the extent of absorption is constant with a decrease in microcrystal diameter.

LC-MS/MS method for the determination of the prodrug aripiprazole lauroxil and its three metabolites in plasma and its application to in vitro biotransformation and animal pharmacokinetic studies.

A sensitive and selective LC-MS/MS method for determination of the prodrug aripiprazole lauroxil (AL) and the three metabolites (N-hydroxymethyl aripiprazole [NHA], aripiprazole [ARP], and dehydro aripiprazole [DHA]) in plasma was developed using ARP-d8 as an internal standard. The analytes were determined on an AB Sciex Triple Quad™ 4500 system using positive ion electrospray ionization and selected multiple reaction monitoring mode. Solid phase extraction was applied for sample preparation for AL, ARP, and DHA, and protein precipitation for NHA. Chromatographic separation was performed on an Agilent Eclipse XDB-CN column (100 × 2.1 mm i.d., 3.5 µm) using the mobile phase of water and acetonitrile (25:75, v/v) containing 0.1% formic acid with a flow rate of 0.5 mL/min. The linear ranges for AL, NHA, ARP, and DHA were 0.5-50 ng/mL, 1.0-50 ng/mL, 0.5-50 ng/mL, and 0.05-5.0 ng/mL, respectively. The average recovery in the plasma sample was stable and reproducible. The precision and accuracy of the intra- and inter-run were within assay variability criteria limits. The developed method was suitable for in vitro biotransformation studies in plasma and animal pharmacokinetic studies after intramuscular injection of AL formulations.

An LC-MS/MS method for the simultaneous determination of goserelin and testosterone in rat plasma for pharmacokinetic and pharmacodynamic studies.

A liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed, using testosterone-d3 as a surrogate analyte, for the simultaneous quantification of goserelin and testosterone in rat plasma. According to this method, the pharmacokinetic and pharmacodynamic data were obtained from a single plasma sample aliquot. The method involved the addition of alarelin as an internal standard (IS) for goserelin and testosterone-(13)C3 for testosterone or testosterone-d3. The conditions for the separation of these two compounds were achieved on a ZORBAX Eclipse Plus C18 column (Agilent, 2.1 × 50 mm, 1.8 µm, Stockport, UK) in a single chromatographic run at a flow rate of 400 µL/min. In order to minimize interferences of complex matrix, the extraction of plasma consisted of a protein precipitation step using methanol, followed by purification using an Oasis(®) HLB solid-phase extraction column. The method was validated in the concentration range of 0.01-30.0 ng/mL for goserelin and 0.05-30.0 ng/mL for testosterone-d3, respectively. The within- and between-run precisions were 1.7-9.2% and 2.1-6.9%, respectively. The within- and between-run accuracies were -1.8 to 5.3% and -4.9 to 4.0%, respectively. This accurate and highly specific assay provides a useful method to evaluate the pharmacokinetics and pharmacodynamics of goserelin in rats.

An analytical strategy to characterize the pharmacokinetics and pharmacodynamics of triptorelin in rats based on simultaneous LC-MS/MS analysis of triptorelin and endogenous testosterone in rat plasma.

Triptorelin, a gonadotropin-releasing hormone agonist, has been used in the treatment of hormone-responsive prostate cancer by inducing testosterone suppression. Research on the relationship between the time courses of triptorelin and testosterone is very important, but accurate quantification of triptorelin and testosterone simultaneously in biological specimens is a challenging analytical problem. In the present study, a rapid, sensitive, and selective method for simultaneous determination of triptorelin and testosterone in rat plasma by solid-phase extraction and liquid chromatography-tandem mass spectrometry was developed using a ZORBAX RRHD Eclipse Plus C8 column (2.1 × 50 mm, 1.8 µm) with a 0.05% propionic acid/methanol gradient. In view of the polarity difference between the two analytes, two internal standards, i.e., leuprolide and testosterone-(13)C3, were used for individual quantitation of triptorelin and testosterone. Endogenous testosterone was determined by reference to a calibration curve prepared using testosterone-D3 as a surrogate analyte. The method exhibits excellent linearity over three orders of magnitude for each analyte. The lower limit of quantification was 0.01 ng/mL for triptorelin and 0.05 ng/mL for testosterone, with consumption of 100 µL of plasma. The method was successfully applied to characterize the pharmacokinetics and pharmacodynamics of slow-release 28-day form triptorelin acetate biodegradable microspheres in rats after intramuscular injections of three consecutive doses of 0.6 mg/kg per 28 days. The results revealed that the pharmacokinetic profile of triptorelin produced an initial flare-up in testosterone levels, rapid castration within 5 days after injection, and long-term castration until the next dose.

[Characteristics and influencing factors of air pollution in and out of the highway toll gates].

During June and July 2003, CO, NO2, THC and PM10 were sampled at the four highway toll gates in Chongqing. Air temperature, air pressure, wind velocity and traffic flow were also monitored simultaneously. The relation between air pollution parameters and influencing factors was analyzed by applying the methods of bivariate correlation and partial correlation. As shown in the monitoring result, the outdoor average concentrations of CO and PM10 exceed indoor ones, but NO2 and THC are reverse. The average concentrations of CO and NO2 at the toll gates don't exceed the indoor and outdoor air quality standards except for the toll gate in Chongqing and Chayuan. One-hour average concentrations of outdoor and indoor THC are 7.728 mg/m3 and 7.216 mg/m3 respectively, and exceed ten times of the indoor air quality standard. One-hour average concentrations of indoor and outdoor PM10 change acutely respectively, and the their maximum concentrations are 0.631 mg/m3 and 0.217 mg/m3 which exceed indoor air quality standard and the second class of ambient air quality standard. Polluting state of Chongqing toll is the worst among the four sampled tolls, and three indexes are bigger than others. Indoor and outdoor air pollutants have correlativity. Correlations of CO, PM10 and NO2 are significant at the 0.01 level respectively, and correlations between indoor and outdoor THC are significant at the 0.05 level. In the influencing factors analysis, traffic flow is significantly correlative with NO2, THC and PM10 (p < 0.01 or 0.01 < p < 0.05), and not significantly correlative with CO (p > 0.01). Air pressure and ambient temperature are predominating factors which influencing the concentration variation, and wind speed is a minor meteorological factor influencing the fluctuations of the data.