Charge Transfer Copper Chelating Complex and Biogenically Synthesized Copper Oxide Nanoparticles Using Salvia officinalis Laves Extract in Comparative Spectrofluorimetric Estimation of Anticancer Dabrafenib

Cancer is a broad category of disease that can affect virtually any organ or tissue in the body when abnormal cells grow uncontrollably, invade surrounding tissue, and/or spread to other organs. Dabrafenib is indicated for the treatment of adult patients with advanced non-small cell lung cancer. In the present study, two newly developed spectrofluorimetric probes for the detection of the anticancer drug Dabrafenib (DRF) in its authentic and pharmaceutical products using an ecologically synthesized copper oxide nanoparticle (CuONPs) from Salvia officinalis leaf extract and a copper chelate complex are presented. The first system is based on the influence of the particular optical properties of CuONPs on the enhancement of fluorescence detection. The second system, on the other hand, acts through the formation of a copper charge transfer complex. Various spectroscopic and microscopic studies were performed to confirm the environmentally synthesized CuONPs. The fluorescence detections in the two systems were measured at λex 350 and λem of 432 nm. The results showed the linear concentration ranges for the DRF-CuONPs-SDS and DRF-Cu-SDS complexes were determined to be 1.0-500 ng mL- 1 and 1.0-200 ng mL- 1, respectively. FI = 1.8088x + 21.418 (r = 0.9997) and FI = 2.7536x + 163.37 (r = 0.9989) were the regression equations. The lower detection and quantification limits for the aforementioned fluorescent systems were determined to be 0.4 and 0.8 ng mL- 1 and 1.0 ng mL- 1, respectively. The results also showed that intra-day DRF assays using DRF-CuONPs-SDS and DRF-Cu(NO3)2-SDS systems yielded 0.17% and 0.54%, respectively. However, the inter-day assay results for the above systems were 0.27% and 0.65%, respectively. The aforementioned two systems were effectively used in the study of DRF with excellent percent recoveries of 99.66 ± 0.42% and 99.42 ± 0.56%, respectively. Excipients such as magnesium stearate, titanium dioxide, red iron oxide, and silicon dioxide used in pharmaceutical formulations, as well as various common cations, amino acids, and sugars, had no effect on the detection of compound.

Synthesis of (R)-(6-Methoxyquinolin-4-yl)[(1S,2S,4S,5R)-5-vinylquinuclidin-2-yl]methanol Tetraphenylborate Ion-Pair Complex: Characterization, Antimicrobial, and Computational Study

The (R)-(6-Methoxyquinolin-4-yl)[(1S,2S,4S,5R)-5-vinylquinuclidin-2-yl]methanol (quinine)-tetraphenylborate complex was synthesized by reacting sodium tetraphenyl borate with quinine in deionized water at room temperature through an ion-pair reaction (green chemistry) at room temperature. The solid complex was characterized by several physicochemical methods. The formation of ion-pair complex between bio-active molecules and/or organic molecules is crucial to comprehending the relationships between bioactive molecules and receptor interactions. The complex under study was examined for antimicrobial activity. All theoretical calculations were carried out in vacuum and water using the B3LYP level 6-311G(d,p) levels of theory. The theoretical computation allowed for the prediction and visualization of ionic interactions, which explained the complex's stability. The results of energy optimization showed that the Q-TPB complex is stable with a negative complexation energy. The obtained geometries showed that the boron (B-) and nitrogen (N+) in piperidine of the two molecules tetraphenylborate and quinine are close to each other, which makes it possible for ions to interact. The modest energy gap between HOMO and LUMO showed that the compound was stable. The computation of the electron transitions of the two models by density functional theory (TD-DFT) in the solvent at the theoretical level B3LYP/6-311G(d,p) allowed for the detection of three UV/visible absorption bands for both models and the discovery of a charge transfer between the host and the guest. The UV absorption, infrared, and H NMR are comparable with the experimental part.

Fabrication and Applications of Potentiometric Membrane Sensors Based on Specific Recognition Sites for the Measurement of the Quinolone Antibacterial Drug Gemifloxacin

Supramolecular gemifloxacin (GF) sensors have been developed. Supramolecular chemistry is primarily concerned with noncovalent intermolecular and intramolecular interactions, which are far weaker than covalent connections, but they can be exploited to develop sensors with remarkable affinity for a target analyte. In order to determine the dose form of the quinolone antibacterial drug gemifloxacin, the current study's goal is to adapt three polyvinylchloride (PVC) membrane sensors into an electrochemical technique. Three new potentiometric membrane sensors with cylindric form and responsive to gemifloxacin (GF) were developed. The sensors' setup is based on the usage of o-nitrophenyl octyl ether (o-NPOE) as a plasticizer in a PVC matrix, β-cyclodextrin (β-CD) (sensor 1), γ-cyclodextrin (γ-CD) (sensor 2), and 4-tert-butylcalix[8]arene (calixarene) (sensor 3) as an ionophore, potassium tetrakis (4-chlorophenyl) borate (KTpClPB) as an ion additive for determination of GF. The developed method was verified according to IUPAC guidelines. The sensors under examination have good selectivity for GF, according to their selectivity coefficients. The constructed sensors demonstrated a significant response towards to GF over a concentration range of 2.4 × 10^-6, 2.7 × 10^-6, and 2.42 × 10^-6 mol L^-1 for sensors 1, 2, and 3, respectively. The sensors showed near-Nernstian cationic response for GF at 55 mV, 56 mV, and 60 mV per decade for sensors 1, 2, and 3, respectively. Good recovery and relative standard deviations during the day and between days are displayed by the sensors. They demonstrated good stability, quick response times, long lives, rapid recovery, and precision while also exhibiting good selectivity for GF in various matrices. To determine GF in bulk and dose form, the developed sensors have been successfully deployed. The sensors were also employed as end-point indicators for titrating GF with sodium tetraphenyl borate.

Fabrication and Applications of Potentiometric Membrane Sensors Based on γ-Cyclodextrin and Calixarene as Ionophores for the Determination of a Histamine H1-Receptor Antagonist: Fexofenadine

Supramolecular fexofenadine sensors have been constructed. Although noncovalent intermolecular and intramolecular interactions, which are far weaker than covalent contacts, are the main focus of supramolecular chemistry, they can be used to create sensors with an exceptional affinity for a target analyte. The objective of the current research study is to adapt two PVC membrane sensors into an electrochemical approach for the dosage form determination of histamine H1-receptor antagonists: fexofenadine. The general performance characteristics of two new modified potentiometric membrane sensors responsive to fexofenadine hydrochloride were established. The technique was based on the employment of γ-cyclodextrin (CD) (sensor 1), 4-tert-butylcalix[8]arene (calixarene) (sensor 2) as an ionophore, potassium tetrakis (4-chlorophenyl) borate (KTpClPB) as an ion additive, and (o-NPOE) as a plasticizer for sensors 1 and 2. The sensors showed fast responses over a wide fexofenadine concentration range (1 × 10^-2 to 4.5 (4.7) × 10^-6 M), with detection limits of 1.3 × 10^-6 M and 1.4 × 10^-6 M for sensors 1 and 2, respectively, in the pH range of 2-8. The tested sensors exhibit the fexofenadine near-Nernstian cationic response at 56 and 58 mV/decade for sensors 1 and 2, respectively. The sensors exhibit good stability, fast response times, accuracy, precision, and longer life for fexofenadine. Throughout the day and between days, the sensors exhibit good recovery and low relative standard deviations. Fexofenadine in its pure, dose form has been identified with success using the modified sensors. The sensors were employed as end-point indications for the titration of fexofenadine with NaTPB.

Atropine-Phosphotungestate Polymeric-Based Metal Oxide Nanoparticles for Potentiometric Detection in Pharmaceutical Dosage Forms

The new research presents highly conductive polymeric membranes with a large surface area to volume ratio of metal oxide nanoparticles that were used to determine atropine sulfate (AT) in commercial dosage forms. In sensing and biosensing applications, the nanomaterials zinc oxide (ZnONPs) and magnesium oxide (MgONPs) were employed as boosting potential electroactive materials. The electroactive atropine phosphotungstate (AT-PT) was created by combining atropine sulfate and phosphotungstic acid (PTA) and mixing it with polymeric polyvinyl chloride (PVC) with the plasticizer o-nitrophenyl octyl ether (o-NPOE). The modified sensors AT-PT-ZnONPs or AT-PT-MgONPs showed excellent selectivity and sensitivity for the measurements of atropine with a linear concentration range of 6.0 × 10⁻⁸ − 1.0 × 10⁻³ and 8.0 × 10⁻⁸ − 1.0 × 10⁻³ mol L⁻¹ with regression equations of E_(mV) = (56 ± 0.5) log [AT] − 294 and E_(mV) = (54 ± 0.5) log [AT] − 422 for AT-PT-NPs or AT-PT-MgONPs sensors, respectively. The AT-PT coated wire sensor, on the other hand, showed a Nernstian response at 4.0 × 10⁻⁶ − 1.0 × 10⁻³ mol L⁻¹ and a regression equation E_(mV) = (52.1 ± 0.2) log [AT] + 198. The methodology-recommended guidelines were used to validate the suggested modified potentiometric systems against various criteria.

Rapid and sensitive LC-MS/MS method for the enantioanalysis of verapamil in rat plasma using superficially porous silica isopropyl-cyclofructan 6 chiral stationary phase after SPE: Application to a stereoselective pharmacokinetic study

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the rapid and sensitive enantioselective analysis of verapamil (VER) in rat plasma was developed and validated using new superficially porous silica isopropyl-cyclofructan 6 chiral column (LarihcShell-P, LSP). The isocratic mobile phase composed of acetonitrile: trifluoroacetic acid: 10 mM ammonium formate (100 : 0.1 : 0.1, v/v/v) at a flow rate of 0.3 mL/min was applied. Sulpride was utilized as the internal standard (IS). Positive multiple reaction monitoring (MRM) mode was used for mass spectrometry analysis, and the process of analysis was run for 5.2 min. The (S)-(-)- and (R)-(+)-VER enantiomers with the IS were extracted from plasma by using solid-phase extraction (SPE) procedure before the analysis. The C18 cartridge gave good recovery rates for both enantiomers without interference from plasma endogenous. The developed assay was successfully validated following the US-FDA guidelines. The method was linear over concentration ranges of 0.5-500 ng/mL (r² ≥ 0.997) for each enantiomer (plasma). The lower limits of quantification (LLOQ) for both isomers were 0.5 ng/mL. The intra- and inter-day relative standard deviations (RSD) were less than 8.7 % and the recoveries of (S)-(-)- and (R)-(+)-VER at three spiked levels of 1.5, 250.0 and 450.0 ranged from 92.0%-98.6%. The developed assay was effectively applied in monitoring the stereoselective pharmacokinetic study of VER enantiomers in rat plasma following oral administration of racemic VER. The pharmacokinetic parameters revealed that (S)-(-)-VER demonstrated prominently higher C_max and AUC values than (R)-(+)-enantiomer. The newly developed approach is the first chiral LC-MS/MS for the quantification of (S)-(-)- and (R)-(+)-VER utilizing superficially porous silica isopropyl-cyclofructan 6 chiral column in rat plasma after SPE.

Bioanalytical Method Development and Validation for the Determination of Vasopressin Receptor Antagonist Conivaptan in Mouse Plasma at NanoLevel and its Pharmacokinetic Application

Background:

Conivaptan inhibits two of vasopressin receptor (vasopressin receptor V1a and V2). Conivaptan is used for the treatment of hyponatremia, and in some instances, for the treatment of the heart failure.

Methods:

The present study aimed to develop a simple, sensitive, and accurate HPLC with ultraviolet detection for the assay of conivaptan (CON) in mouse plasma using bisoprolol as internal standard (IS). A precipitation procedure was used to extract CON and the IS from the mouse plasma. CON was chromatographically separated using a C18 analytical column at 25°C. The separation was carried out using a mixture of phosphate buffer (50 mM): acetonitrile (60: 40, v/v, pH 4.5) with a flow rate of 1.0 mL/min and detection was performed at 240 nm.

Results:

The assay was validated according to the US Food and Drug (FDA) guidelines. The method demonstrated linearity over a concentration range of 150 - 2000 ng/mL (correlation coefficient: r 2 = 0.9985). The mean recovery of CON from the mouse plasma was 101.13%. All validation parameters for CON were within the acceptable range.

Conclusion:

The investigated method has been shown to be suitable for estimating the CON in plasma samples, and this method is sensitive and highly selective, allowing the estimation of its concentrations up to the nano-scale. The suggested method was successfully used in a pharmacokinetic study of CON in mouse plasma.

Comparative study of β-cyclodextrin, γ-cyclodextrin and 4-tert-butylcalix[8]arene ionophores as electroactive materials for the construction of new sensors for trazodone based on host-guest recognition

BACKGROUND

Trazodone (TRZ) is a second-generation non-tricyclic antidepressant derived from a triazolopyridine derivative, which is mainly used to treat emotional disorders and conditions related to depressive disorders.

PURPOSE

This study investigated the design, development and characteristics of polyvinyl chloride (PVC) membrane sensors for trazodone HCl (TRZ).

METHODS

The developed sensing membranes were constructed using β-cyclodextrin (β-CD; sensor 1), γ-cyclodextrin (γ-CD; sensor 2) or 4-tert-butylcalix[8]arene (t-BC8; sensor 3) ionophores as sensing materials in addition to ionic sites and dioctyl phthalate in the PVC matrix.

RESULTS

Sensors 1, 2 and 3 displayed fast, stable and near-Nernstian response over a relatively wide trazodone concentration range (7.0×10-6-1×10-3, 5.0×10-5-1×10-3and 8.0×10-6-1.0×10-3 M, respectively), with detection limits of 2.2×10-6, 1.5×10-5 and 2.42×10-6 M, respectively in the pH range of 3.0-6.0. The sensors demonstrated good selectivity for TRZ in the presence of different ionic compounds. The accuracy and precision of the proposed sensors were assessed by the determination of 40.7 μg/ml of TRZ, which showed average recoveries of 99.6%, 99.1% and 98.5% with mean relative standard deviations of 2.4%, 2.5% and 2.6% for sensor 1, 2 and 3 respectively. Molecular modeling was used to calculate the host-guest binding energy. The lowest free binding energy was -6.243, -5.752 and -5.7105 kcal/mol for 1:1 stoichiometry host-guest complexes of trazodone and β-CD, γ-CD and t-BC8, respectively, which was in-line with a Nernstian response.

CONCLUSION

The investigated methods can be applied for the determination of TRZ in pharmaceutical preparations. The results of investigated dosage-form of TRZ show good agreement with those using the US Pharmacopeia method.

Levetiracetam

A comprehensive profile of levetiracetam is presented in this chapter which includes its description, formula, elemental analysis, appearance, uses and applications. Different earlier studies included for example methods of synthesis are described with its typical structural schemes. The profile also listed the drug's physical characteristics indicating its solubility, X-ray powder diffraction pattern, thermal methods of analysis as well as its spectroscopic characteristics. Different methods of analysis which includes compendial method of analysis, as well as reported method of analysis which include spectrophotometry, spectrofluorometry, electrochemical method, chromatographic method, and immunoassay method of analysis. The study was include drug stability, clinical pharmacology, e.g., mechanism of action, pharmacokinetic study. Around 70 references are recorded as a proof of this chapter.

Validated Microemulsion Liquid Chromatography-Fluorescence Method for the Quantification of Duloxetine and its Two Main Metabolites in Plasma: Application to Clinical Pharmacokinetic Studies

Background:

Duloxetine (DL) is a selective serotonin and norepinephrine reuptake inhibitor. The drug is used in the treatment of major depression, anxiety, pain related to diabetic peripheral neuropathy and stress urinary incontinence. </P><P> Objective: This study described, for the first time, the development and validation of a highly selective and sensitive microemulsion liquid chromatography-fluorescence (MELC-FL) method with low environmental pollution and without extraction steps for the simultaneous quantification of DL, and its two main metabolites; 5-hydroxy-6-methoxy duloxetine (5-HDL) and 4-hydroxy duloxetine glucuronide (4- HDLG) in plasma.

Methods:

The studied analytes and methyl paraben (an internal standard) were detected using excitation and emission wavelengths of 280 and 340 nm, respectively. The analysis was performed on Water Symmetry C18 analytical column (100 Å, 150 mm x 3.9 mm, 5 µm) by directly injecting the plasma after appropriate dilution with microemulsion mobile phase. Total analytical run time was 4 min.

Results:

The MELC-FL method was statistically validated according to the FDA guidelines for bioanalytical methods for linearity, accuracy, precision, specificity, robustness, and stability. Linear calibration plots were achieved in the ranges of 25-1200 ng/mL for DL and 50-1500 ng/mL for 5-HDL and 4- HDLG (r2 ≥ 0.997) in rat plasma. The intra- and inter- assay precisions and accuracy were acceptable. The overall recoveries of DL and its two main metabolites from rat plasma were between 97.12% and 103.12% with an RSD value between 0.34% and 4.57%.

Conclusion:

The present study supports the possible use of the microemulsion mobile phase in LC as a “greener ” mobile phase. The developed method offered an advantage in the form of direct analysis of biological samples after appropriate dilution with eco-friendly microemulsion mobile phase, which decreased the possibility of sample loss during analysis. The developed assay was successfully applied in a pharmacokinetic study and it established the applicability of the method for the determination of concentration-time profiles of DL and its two main metabolites in rat plasma after systemic administration.

A simple liquid chromatography-tandem mass spectrometry method to accurately determine the novel third-generation EGFR-TKI naquotinib with its applicability to metabolic stability assessment

Naquotinib (ASP8273, NQT) is a novel third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKIs). NQT was found to be more effective than osimertinib against the EGFR L858R plus T790M mutation (L858R+T790M). A rapid resolution liquid chromatography (RRLC)-tandem mass spectrometry (MS/MS) method was developed and validated for NQT quantification and its metabolic stability was investigated. NQT and foretinib (FTB) as an internal standard (IS) were separated using a mobile phase under isocratic conditions with a C18 column (reversed phase system). The linearity of the analytical method ranged from 5 to 500 ng mL⁻¹ (coefficient of correlation [r²] ≥ 0.9999) in a human liver microsome (HLM) matrix. The limit of detection and limit of quantification were 0.78 and 2.36 ng mL⁻¹, respectively. The inter-day and intra-day accuracy and precision were −6.36 to 1.88 and 0.99 to 2.58%, respectively. The metabolic stability of NQT in the HLM matrix was calculated using the in vitro half-life (t_1/2, 67.96 min) and intrinsic clearance (Cl_int, 2.12 mL min⁻¹ kg⁻¹). NQT is considered to be a moderate extraction ratio drug that is moderately excreted from the human body compared with other related TKIs. This proposed methodology is thought to be the first method for assessing NQT concentration and its metabolic stability.

The first established LC-MS/MS method for NQT analysis. NQT was shown to be moderately excreted from the human body.

Cellular responses of hyaluronic acid-coated chitosan nanoparticles

In recent years, nanotechnology has been proven to offer promising biomedical applications for in vivo diagnostics and drug delivery, stressing the importance of thoroughly investigating the biocompatibility of potentially translatable nanoparticles (NPs). Herein, we report the cellular responses of uncoated chitosan NPs (CS NPs) and hyaluronic acid-coated chitosan NPs (HA-CS NPs) when introduced into Chinese hamster ovary cells (CHO-K1) in a dose-dependent manner (2.5, 0.25, 0.025, 0.0025, and 0.00025 mg mL-1) at two time points (24 and 48 h). MTS assay, cell proliferation, showed a decrease in the viability of cells when treated with 0.25 and 2.5 mg mL-1 CS NPs. When exposed to high doses of CS NPs, the lactate dehydrogenase (LDH) enzyme started to leak out of the cells and the cellular levels of mitochondrial potentials were significantly reduced accompanied by a high production of intracellular reactive oxygen species (ROS). Our study provides molecular evidence of the biocompatibility offered by HA-CS NPs, through ROS scavenging capabilities rescuing cells from the oxidative stress, showing no observed cellular stress and thereby revealing the promising effect of anionic hyaluronic acid to significantly reduce the cytotoxicity of CS NPs. Our findings are important to accelerate the translation and utilization of HA-CS NPs in drug delivery, demonstrating the pronounced effect of surface modifications on modulating the biological responses.

A reliable and stable method for the determination of foretinib in human plasma by LC-MS/MS: Application to metabolic stability investigation and excretion rate

Foretinib (GSK1363089) is a multiple receptor tyrosine kinases inhibitor. In this study, a reliable, fast liquid chromatography-tandem mass spectrometric method was described for assaying foretinib in plasma, urine, and rat liver microsome samples. Simple extraction procedure by protein preciptation with acetonitrile was implemented for foretinib and brigatinib (internal standard) analysis. Chromatographic resolution of analytes was achieved on C₁₈ column with the help of isocratic mobile phase. The binary mobile phase consisted of 60% ammonium formate (10 mM, pH 4.2) and 40% acetonitrile at a flow rate of 0.25 mL/min. Run time was 3 min, and both foretinib and brigatinib were eluted within 0.74 and 1.95 min; they were detected in positive ion mode utilizing multiple reactions monitoring mode. Linearity of the proposed method ranged from 5 to 500 ng/mL (r²≥ 0.9993) in the human plasma. Lower limit of quantification and detection were 6.0 and 1.8 ng/mL, respectively. Intraday and interday precision and accuracy were 0.16 to 1.67 % and -2.39 to -0.52 %. In vitro half-life and intrinsic clearance were 24.93 min and 6.56 mL/min/kg, respectively. Literature review showed that no previous studies have been proposed for the analytical quantification of foretinib in human plasma or its metabolic stability. The established method was also applied to estimate the rate of foretinib excretion in rat urine. The developed method can be used for foretinib pharmacokinetic applications.

LC-MS/MS reveals the formation of iminium and quinone methide reactive intermediates in entrectinib metabolism: In vivo and in vitro metabolic investigation

Entrectinib (RXDX-101) is orally available inhibitor of the tyrosine kinases including tropomyosin receptor kinases (Trk) A-C, C-ros oncogene 1 (ROS1) and anaplastic lymphoma kinase (ALK), with potential antineoplastic activity. Entrectinib (ENB) granted breakthrough designation by FDA for NTRK + Solid tumors. In vitro metabolism of ENB generates quinone methide and iminium reactive intermediates that were captured by potassium cyanide and GSH, respectively forming stable conjugates that were characterized by LC-MS/MS. Seven in vitro ENB metabolites were identified through four metabolic reactions including hydroxylation, N-dealkylation, N-oxidation and reduction. Furthermore, four reactive intermediates including two quinone methide and two iminium ions were detected and the bioactivation mechanisms were supposed. In vivo metabolism of ENB was done by giving single oral dose (35.2 mg/kg) to Sprague Dawley rats. In vivo metabolism generates five phase I metabolites similar to in vitro metabolism except no metabolic reactions were identified on indazole ring. One phase II metabolite was characterized in in vivo metabolism of ENB resulted from glucuronidation of hydroxyl metabolite of ENB. Reporting these data for ENB is very crucial in the development stage. Reviewing literatures revealed the absence of previous articles have been done for the ENB in vitro or in vivo metabolism study or structural characterization of the formed reactive intermediates.

A new selective, and sensitive method for the determination of lixivaptan, a vasopressin 2 (V2)-receptor antagonist, in mouse plasma and its application in a pharmacokinetic study

A new, selective and sensitive HPLC method for the determination of lixivaptan, an oral selective vasopressin 2 (V2)-receptor antagonist, was investigated and validated. A Waters symmetry C18 column was used as a stationary phase in isocratic elution mode using a mobile phase composed of KH2PO4(100 mM)-acetonitrile (40: 60, v/v) at a flow rate of 1.5 mL min-1. Diclofenac was used as the internal standard (IS). Lixivaptan and the IS were extracted from plasma by protein precipitation and were detected at 260 nm. Lixivaptan and diclofenac were eluted at 3.6 and 6.2 min, respectively. The developed method showed good linearity over the calibration range of 50 -1000 ng mL-1with a lower limit of detection of 16.5 ng mL-1. The extraction percentage of lixivaptan in the mouse plasma was in the range of 88.88 - 114.43%, which indicates acceptable extraction. The aforementioned method was validated according to guidelines of the International Council on Harmonization (ICH). The intra- and inter-day coefficients of variation did not exceed 5.5%. This method was presented to be simple, sensitive, and accurate and was successfully adapted in a pharmacokinetic study of the profile of lixivaptan in mouse plasma. A mean maximum plasma concentration of lixivaptan of 113.82 ng mL-1was achieved in 0.5 h after oral administration of a 10 mg kg-1dose in mouse as determined using the developed method.

Development and validation of an HPLC-MS/MS method for the determination of arginine-vasopressin receptor blocker conivaptan in human plasma and rat liver microsomes: application to a metabolic stability study

Purpose

To develop and validate a bio-analytical HPLC–MS/MS method for the determination of conivaptan (CVA) an arginine-vasopressin receptor blocker in human plasma and in rat liver microsomes (RLMs).

Methods

Analytes were separated on a reversed phase C18 column (50 mm × 2.1 mm, 1.8 μm). The mobile phase was a mixture of acetonitrile and 10 mM ammonium formate (40:60 v/v, pH 4.0) and was pumped isocratically for 4 min at a flow rate of 0.2 ml/min. Multiple reaction monitoring in positive ionization mode was used for the assay.

Results

The method yielded a linear calibration plot (r²= 0.9977 and 0.9998) over 5–500 ng/ml with a limit of detection at 1.52 and 0.88 ng/ml for human plasma and RLMs, respectively. The reproducibility of detection of CVA in human plasma and RLMs was found to be in an acceptable range.

Conclusion

The method developed in this study is applicable for accurately quantifying CVA in human plasma and rat liver microsomal samples. The optimized procedure was applied to study of metabolic stability of CVA. Conivaptan concentration rapidly decreased in the first 2 min of RLMs incubation and the conversion reached a plateau for the remainder of the incubation period. The in vitro half-life (t_1/2) was estimated at 11.51 min and the intrinsic clearance (CL_in) was 13.8 ± 0.48 ml/min/kg.

LC-MS/MS reveals the formation of reactive ortho-quinone and iminium intermediates in saracatinib metabolism: Phase I metabolic profiling

Saracatinib (AZD-0530) is a drug under clinical trials that developed by AstraZeneca. It is considered a dual kinase inhibitor, with selective actions as a Src inhibitor and a Bcr-Abl tyrosine-kinase inhibitor. Saracatinib chemical structure contains N-methyl piperazine group and 1,3 benzodioxole group. N-methyl piperazine group that can be bioactivated to form iminium intermediates which can be captured by KCN. 1,3-Benzodioxole group can be bioactivated to form ortho-quinone intermediate that can be conjugated with GSH. The formed conjugates are stable and can be identified using LC-MS/MS. In our current work, we are trying to give insight into the reasons that may be responsible for saracatinib side effects. Using LC-MS/MS, in vitro metabolic pathways were investigated for saracatinib in rat liver microsomes. Ten saracatinib phase I metabolites were characterized and the metabolic pathways were found to be hydroxylation, oxidation, reduction, dealkylation, N-oxidation and ether cleavage. Also, four potential reactive intermediates (three cyanide adducts and one GSH conjugate) were identified and the bioactivation mechanisms were explained. The existence of these four reactive metabolites may be the main reason for observed saracatinib side effects in clinical trials. Literature review showed no previous articles have been proposed the detailed structural identification of the formed reactive metabolites.

Hyaluronic Acid Coated Chitosan Nanoparticles Reduced the Immunogenicity of the Formed Protein Corona

Studying the interactions of nanoparticles (NPs) with serum proteins is necessary for the rational development of nanocarriers. Optimum surface chemistry is a key consideration to modulate the formation of the serum protein corona (PC) and the resultant immune response. We investigated the constituent of the PC formed by hyaluronic acid-coated chitosan NPs (HA-CS NPs). Non-decorated chitosan NPs (CS NPs) and alginate-coated chitosan NPs (Alg-CS NPs) were utilized as controls. Results show that HA surface modifications significantly reduced protein adsorption relative to controls. Gene Ontology analysis demonstrates that HA-CS NPs were the least immunogenic nanocarriers. Indeed, less inflammatory proteins were adsorbed onto HA-CS NPs as opposed to CS and Alg-CS NPs. Interestingly, HA-CS NPs differentially adsorbed two unique anti-inflammatory proteins (ITIH4 and AGP), which were absent from the PC of both controls. On the other hand, CS and Alg-CS NPs selectively adsorbed a proinflammatory protein (Clusterin) that was not found on the surfaces of HA-CS NPs. While further studies are needed to investigate abilities of the PCs of only ITIH4 and AGP to modulate the interaction of NPs with the host immune system, our results suggest that this proof-of-concept could potentially be utilized to reduce the immunogenicity of a wide range of nanomaterials.

Development and validation of HPLC-MS/MS method for the determination of lixivaptan in mouse plasma and its application in a pharmacokinetic study

The aim of the present study was to develop a simple, sensitive and accurate liquid chromatography-electrospray ionization tandem mass spectrometry (ESI-MS/MS) method for the determination of lixivaptan (LIX) in mouse plasma using vildagliptin as the internal standard (IS). A precipitation procedure was used for the extraction of LIX and vildagliptin from mouse plasma. Chromatographic separation of LIX was achieved using a C₁₈ analytical column (50 × 2.1 mm, 1.8 μm) at 25°C. The mobile phase comprised acetonitrile and ammonium formate (10 mm, pH 3.1; 40:60, v/v) pumped at a flow rate of 0.3 mL min^-1 . A tandem mass spectrometer with an electrospray ionization source was used to perform the assay. Quantification of LIX at m/z 290 → 137 and IS at 154 → 97 was attained through multiple reaction monitoring. The investigated method was authenticated following the bio-analytical method of validation guidelines of the US Food and Drug Administration. The developed method showed a good linearity over the concentration range from 5 to 500 ng mL^-1 , and the calibration curve was linear (r = 0.9998). The mean recovery of LIX from mouse plasma was 99.2 ± 0.68%. All validation parameters for LIX were within the levels required for acceptance. The proposed method was effectively used for a pharmacokinetic study of LIX in mouse plasma.

Ionophore-based potentiometric PVC membrane sensors for determination of phenobarbitone in pharmaceutical formulations

The fabrication and development of two polyvinyl chloride (PVC) membrane sensors for assaying phenobarbitone sodium are described. Sensors 1 and 2 were fabricated utilizing β- or γ-cyclodextrin as ionophore in the presence of tridodecylmethylammonium chloride as a membrane additive, and PVC and dioctyl phthalate as plasticizer. The analytical parameters of both sensors were evaluated according to the IUPAC guidelines. The proposed sensors showed rapid, stable anionic response (-59.1 and -62.0 mV per decade) over a relatively wide phenobarbitone concentration range (5.0 × 10-6-1 × 10-2 and 8 × 10-6-1 × 10-2 mol L-1) in the pH range of 9-11. The limit of detection was 3.5 × 10-6 and 7.0 × 10-6 mol L-1 for sensors 1 and 2, respectively. The fabricated sensors showed high selectivity for phenobarbitone over the investigated foreign species. An average recovery of 2.54 μg mL-1 phenobarbitone sodium was 97.4 and 101.1 %, while the mean relative standard deviation was 3.0 and 2.1 %, for sensors 1 and 2, respectively. The results acquired for determination of phenobarbitone in its dosage forms utilizing the proposed sensors are in good agreement with those obtained by the British Pharmacopoeial method.