Simultaneous determination of propofol and remifentanil in rat plasma by liquid chromatography–tandem mass spectrometry: application to preclinical pharmacokinetic drug–drug interaction analysis

Propofol (Pro) is an ultra‐short‐acting hypnotic agent used for general anesthesia that has no analgesic properties. Remifentanil (Rem) is an ultra‐short‐acting opioid administered concomitantly as an analgesic with Pro. To evaluate the pharmacokinetic interactions between Pro and Rem, we developed and validated a method combining high‐performance liquid chromatography with tandem mass spectrometry for simultaneous determination of Pro and Rem. The proposed method was successfully used to study the pharmacokinetic interactions of Pro and Rem coadministered to rats. Copyright © 2014 John Wiley & Sons, Ltd.     

The effect of naringenin on the pharmacokinetics of ibrutinib in rat: A drug–drug interaction study

The aim of this study was to investigate the effect of naringenin on the pharmacokinetics of ibrutinib in rats. A simple and sensitive quantitation method based on ultra‐high‐performance liquid chromatography–Q‐Exactive Orbitrap tandem mass spectrometry was developed and validated for the determination of ibrutinib in rat plasma. The samples were extracted using ethyl acetate containing 1% triethylamine and separated on a Waters Acquity UPLC BEH C₁₈ column with acetonitrile and water containing 0.1% formic acid as mobile phase. The assay showed good linearity over the concentration range of 1–1000 ng/mL with coefficient of correlation >0.995. The LLOQ was 1 ng/mL. The assay showed acceptable precision (RSD < 8.65%), accuracy (RE within ±15%), extraction recovery (>78.25%) and negligible matrix effects. The validated method has been successfully applied to the pharmacokinetic study of ibrutinib in rats after oral administration of ibrutinib with or without coadministration of naringenin. Our results demonstrated that naringenin could significantly affect the pharmacokinetics of ibrutinib, including prolonging its half‐life, increase the area under the concentration–time curve and reducing its clearance time. This study indicated that there is potential for drug–drug interactions between naringenin and ibrutinib, and coadministration of ibrutinib with naringenin or naringenin‐containing herbal medicines should be avoided in the clinic.     

Interaction energy‐based drug–receptor interaction study of metal–bicyclam complexes

Bicyclams inhibit HIV replication by binding to the CXCR4 chemokine receptor, which is the main coreceptor for gp120 used by X4, T‐tropic strains of HIV for membrane fusion and cell entry. Bicyclam AMD3100 mainly interacts with the aspartic acid residues namely Asp171 and Asp262, which are located at the extracellular ends in the CXCR4 coreceptor. Incorporation of some metal ions by the macrocyclic rings of bicyclam enhances its binding affinity to the CXCR4 receptor and enhances their anti‐HIV activity because the acetate can make a strong coordination bond to the metal and one weaker hydrogen bond to nitrogen in the cyclam ring. The interaction energy (E_int) between 150 metal–bicyclam complexes and aspartic acid has been evaluated. The metal–bicyclam complexes are obtained by the incorporation of six metal ions namely Fe³⁺, Co³⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Pd²⁺ in 25 well‐known bicyclams including AMD3100. In most of the cases, Fe and Co–bicyclam complexes interact best with aspartic acid. The anti‐HIV activity of metal–bicyclam complexes can be predicted on the basis of interaction energy before the synthesis of the metal–bicyclam complex. On the basis of interaction energy, the anti‐HIV activity of bicyclam complexes can be predicted in advance to their synthesis. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Simultaneous bioanalysis and pharmacokinetic interaction study of acebrophylline,levocetirizine and pranlukast in Sprague–Dawley rats

The combination of acebrophylline (ABP), levocetirizine (LCZ) and pranlukast (PRN) is used to treat allergic rhinitis, asthma, hay‐fever and other conditions where patients experience difficulty in breathing. This study was carried out with the aim of developing and validating a reverse‐phase high‐performance liquid chromatographic bioanalytical method to simultaneously quantitate ABP, LCZ and PRN in rat plasma. The objective also includes determination of the pharmacokinetic interaction of these three drugs after administration via the oral route after individual and combination treatment in rat. Optimum resolution between the analytes was observed with a C₁₈ Kinetex column (250 mm × 4.6 mm × 5 μm). The chromatography was performed in a gradient elution mode with a 1 mL/min flow rate. The calibration curves were linear over the concentration range of 100–1600 ng/mL. The intra‐ and inter‐day precision and accuracy were found to be within acceptable limits as specified in US Food and Drug Administration guideline for bioanalytical method validation. The analytes were stable on the bench‐top (8 h), after three freeze–thaw cycles, in the autosampler (8 h) and as a dry extract (?80°C for 48 h). The statistical results of the pharmacokinetic study in Sprague–Dawley rats showed a significant change in pharmacokinetic parameters for PRN upon co‐administration of the three drugs.     

Two high‐performance liquid chromatography–tandem mass spectrometry methods for determination of edaravone and taurine in human plasma: Application to drug–drug interaction and pharmacokinetic studies

Two high‐performance liquid chromatography–tandem mass spectrometry methods were developed and validated for the quantification of edaravone (method A) or taurine (method B) in human plasma. After protein precipitation, separations were achieved on an Ultimate XB‐C8 (2.1 × 50 mm, 3.0 µm) column for edaravone and a ZORBAX SB‐Aq column (2.1 × 100 mm, 3.5 µm) for taurine, respectively. The detection used electrospray ionization source via multiple reaction monitoring in positive‐ion mode for edaravone and negative‐ion mode for taurine, respectively. The lower limits of quantification were 10.0 ng/mL for edaravone and 3.00 μg/mL for taurine. The selectivity, accuracy, and precision of the methods were all within acceptable limits. Two methods were successfully applied to a drug–drug interaction study and a pharmacokinetic study of edaravone and taurine in healthy Chinese volunteers after intravenous infusion of single or compound injection. The results showed that co‐administration of edaravone with taurine increased the C_max and AUC_0‐24 of taurine in human plasma while taurine did not affect the systemic exposure of edaravone. Edaravone and taurine have the dose‐dependent pharmacokinetic profiles in human.     

Rapid solid‐phase extraction coupled with GC–MS method for the determination of venlafaxine in rat plasma: Application to the drug–drug pharmacokinetic interaction study of venlafaxine combined with fluoxetine

A rapid and sensitive gas chromatography with mass spectrometry method for the determination of venlafaxine in rat plasma has been developed and applied to a drug–drug interaction study of fluoxetine on pharmacokinetics of venlafaxine in rats. Rat plasma was spiked with 2% aqueous ammonia before subjected to preactivated C₁₈ solid‐phase extraction columns and eluted with methanol. No endogenous interferences were observed under optimal condition. The calibration curve was linear (R ² = 0.9994) in the range of 10–1000 ng/mL. The quantification limit of venlafaxine in rat plasma was 10 ng/mL. The accuracy was in the range of 85–110%, and the extraction recovery was no less than 50%. Both the intra‐ and interday precision were 5.0–10.7%. The concentration–time curve showed that plasma concentrations of the coadministration group (group B) were higher than that of single dose group (group A). Both values of C _max (0.069 mg/L) and AUC_0→∞ (0.291 mg h/L) in group B were statistically greater than that of C _max (0.046 mg/L) and AUC_0→∞ (0.181 mg·h/L) in group A (P  < 0.05). The results indicated that a significant effect of fluoxetine was shown on the pharmacokinetics of venlafaxine, suggesting that drug–drug interactions are of concern for the treatment of depression with the combined use of venlafaxine and fluoxetine.     

Development and application of a UPLC‐MS/MS method for simultaneous determination of fenofibric acid and berberine in rat plasma: application to the drug–drug pharmacokinetic interaction study of fenofibrate combined with berberine after oral administration in rats

With the purpose of carrying out pharmacokinetic interaction studies ofnberberine (BBR) and fenofibrate (FBT), an UPLC‐MS/MS method has been developed and validated. The analytes, BBR and fenofibric acid (FBA, metabolite of FBT) and the internal standard, tetrahydropalmatine, were extracted with dichloromethane–diethyl ether (3:2, v/v) and separated on an Agilent Eclipse XDB C₁₈ column using a mobile phase composed of acetonitrile and water. With positive ion electrospray ionization, the analytes were monitored on a triple quadrupole mass spectrometer in multiple reaction monitoring mode. Linear calibration curves were obtained over the concentration ranges of 0.1–100.0 ng/mL for BBR and 10.0–50,000.0 ng/mL for FBA. For BBR and FBA, the intra‐ and inter‐day precisions were <11.5 and 11.9%, respectively. The accuracy was within 11.7% and 11.3%. The mean recoveries of BBR at three concentrations of 0.2, 20.0, 80.0 ng/mL were >85.6%, and those of FBA at three concentrations of 20.0, 2500.0, 40,000.0 ng/mL were >87.9%. Consequently, the proposed method was applied to the pharmacokinetic interaction study of FBT combined with BBR after oral administration in rats and was proved to be sensitive, specific and reliable to analyze BBR and FBA in biological samples simultaneously. Copyright © 2016 John Wiley & Sons, Ltd.     

Identification of cytochrome P450 isoforms involved in the metabolism of artocarpin and assessment of its drug–drug interaction

Artocarpin isolated from an agricultural plant Artocarpus communis has shows anti‐inflammation and anticancer activities. In this study, we utilized recombinant human UDP‐glucuronosyltransferasesupersomes (UGTs) and human liver microsomes to explore its inhibitory effect on UGTs and cytochrome p450 enzymes (CYPs). Chemical inhibition studies and screening assays with recombinant human CYPs were used to identify if CYP isoform is involved in artocarpin metabolism. Artocarpin showed strong inhibition against UGT1A3, UGT1A6, UGT1A7, UGT1A8, UGT1A9, UGT1A10, UGT2B7, CYP2C8 and CYP3A4. In particular, artocarpin exhibited competitive inhibition against CYP3A4 and noncompetitive inhibition against UGT1A3 and UGT1A7. The half inhibition concentration values for CYP3A4, UGT1A3 and UGT1A7 were 4.67, 3.82 and 4.82 μm , and the inhibition kinetic parameters for them were 0.78, 2.67 and 3.14 μm , respectively. After artocarpin was incubated in human liver microsomes and determined by HPLC, we observed its main metabolites (M1 and M2). In addition, we proved that CYP2D6 played the key role in the biotransformation of artocarpin in human liver microsomes. The result of molecular docking further confirmed that artocarpin interacted with CYP2D6, CYP2C8 and CYP3A4 through hydrogen bonds. This study provided preliminary results for further research on artocarpin or artocarpin‐containing herbs.     

An evaluation of the CYP2D6 and CYP3A4 inhibition potential of metoprolol metabolites and their contribution to drug–drug and drug–herb interaction by LC‐ESI/MS/MS

The aim of the present study was to evaluate the contribution of metabolites to drug–drug interaction and drug–herb interaction using the inhibition of CYP2D6 and CYP3A4 by metoprolol (MET) and its metabolites. The peak concentrations of unbound plasma concentration of MET, α‐hydroxy metoprolol (HM), O‐desmethyl metoprolol (ODM) and N‐desisopropyl metoprolol (DIM) were 90.37 ± 2.69, 33.32 ± 1.92, 16.93 ± 1.70 and 7.96 ± 0.94 ng/mL, respectively. The metabolites identified, HM and ODM, had a ratio of metabolic area under the concentration–time curve (AUC) to parent AUC of ≥0.25 when either total or unbound concentration of metabolite was considered. In vitro CYP2D6 and CYP3A4 inhibition by MET, HM and ODM study revealed that MET, HM and ODM were not inhibitors of CYP3A4‐catalyzed midazolam metabolism and CYP2D6‐catalyzed dextromethorphan metabolism. However, DIM only met the criteria of >10% of the total drug related material and <25% of the parent using unbound concentrations. If CYP inhibition testing is solely based on metabolite exposure, DIM metabolite would probably not be considered. However, the present study has demonstrated that DIM contributes significantly to in vitro drug–drug interaction. Copyright © 2016 John Wiley & Sons, Ltd.     

Radiation curable materials – principles and new perspectives

Increasing environmental concerns and the ensuing legislation to cut emissions of volatile organic compounds (VOCs) have been major driving forces behind the development of radiation cured coatings over the past 25 years. Today radiation cured coatings are known for their good overall performance and their excellent resistance against chemical and physical surface damages. Advanced photoinitiator systems allow the light stabilisation of UV‐curable formulations and the outdoor application of the coating. The rapid curing, combined with the possibility of immediate processing of the coated objects opens the way for radiation curing – in 100%‐, water based‐, and dual cure systems as well as for radiation curable powder coatings – for a wide variety of application.     

Interaction of zanamivir with DNA and RNA: Models for drug–DNA and drug–RNA bindings

Zanamivir (ZAN) is the first of a new generation of influenza virus-specific drugs known as neuraminidase inhibitors, which acts by interfering with life cycles of influenza viruses A and B. It prevents the virus spreading infection to other cells by blocking the neuraminidase enzyme present on the surface of the virus. The aim of this study was to examine the stability and structural features of calf thymus DNA and yeast RNA complexes with zanamivir in aqueous solution, using constant DNA or RNA concentration (12.5 mM) and various zanamivir/polynucleotide (P) ratios of 1/20, 1/10, 1/4, and 1/2. FTIR and UV–visible spectroscopy are used to determine the drug external binding modes, the binding constant and the stability of zanamivir–DNA and RNA complexes in aqueous solution. Structural analysis showed major interaction of zanamivir with G-C (major groove) and A-T (minor groove) base pairs and minor perturbations of the backbone PO₂ group with overall binding constants of K_{zanamivir–DNA} = 1.30 × 10⁴ M⁻¹ and K_{zanamivir–RNA} = 1.38 × 10⁴ M⁻¹. The drug interaction induces a partial B to A-DNA transition, while RNA remains in A-conformation.     

Predicting drug pharmacokinetic properties using molecular interaction fields and SIMCA

We have developed a method that combines molecular interaction fields with soft independent modeling of class analogy (SIMCA) Wold:1977 to predict pharmacokinetic drug properties. Several additional considerations to those made in traditional QSAR are required in order to develop a successful QSPR strategy that is capable of accommodating the many complex factors that contribute to key pharmacokinetic properties such as ADME (absorption, distribution, metabolism, and excretion) and toxicology. An accurate prediction of oral bioavailability, for example, requires that absorption and first-pass hepatic elimination both be taken into consideration. To accomplish this, general properties of molecules must be related to their solubility and ability to penetrate biological membranes, and specific features must be related to their particular metabolic and toxicological profiles. Here we describe a method, which is applicable to structurally diverse data sets while utilizing as much detailed structural information as possible. We address the issue of the molecular alignment of a structurally diverse set of compounds using idiotropic field orientation (IFO), a generalization of inertial field orientation Clark:1998. We have developed a second flavor of this method, which directly incorporates electrostatics into the molecular alignment. Both variations of IFO produce a characteristic orientation for each structure and the corresponding molecular fields can then be analyzed using SIMCA. Models are presented for human intestinal absorption, blood-brain barrier penetration and bioavailability to demonstrate ways in which this tool can be used early in the drug development process to identify leads likely to exhibit poor pharmacokinetic behavior in pre-clinical studies, and we have explored the influence of conformation and molecular field type on the statistical properties of the models obtained.     

Determination of eurycomanone in rat plasma using hydrophilic interaction liquid chromatography–tandem mass spectrometry for pharmacokinetic study

In this study, a rapid, sensitive, and reliable hydrophilic interaction liquid chromatography–tandem mass spectrometry (HILIC‐MS/MS) method for the determination of eurycomanone in rat plasma was developed and validated. Plasma samples were pretreated with a protein precipitation method and quercitrin was used as an internal standard (IS). A HILIC silica column (2.1 × 100 mm, 3 μm) was used for hydrophilic‐based chromatographic separation, using the mobile phase of 0.1% formic acid with acetonitrile in gradient elution at a flow rate of 0.25 mL/min. Precursor–product ion pairs for multiple‐reaction monitoring were m /z 409.1 → 391.0 for eurycomanone and m /z 449.1 → 303.0 for IS. The linear range was 2–120 ng/mL. The intra‐ and inter‐day accuracies were between 95.5 and 103.4% with a precision of <4.2%. The developed method was successfully applied to the pharmacokinetic analysis of eurycomanone in rat plasma after oral dosing with pure compound and E. longifolia extract. The C _max and AUC_0–t , respectively, were 40.43 ± 16.08 ng/mL and 161.09 ± 37.63 ng h/mL for 10 mg/kg eurycomanone, and 9.90 ± 3.97 ng/mL and 37.15 ± 6.80 ng h/mL for E. longifolia extract (2 mg/kg as eurycomanone). The pharmacokinetic results were comparable with each other, based on the dose as eurycomanone.     

Validated LC‐MS/MS method for the simultaneous determination of hyperoside and 2′′–O‐galloylhyperin in rat plasma: application to a pharmacokinetic study in rats

An LC‐MS/MS method was developed for the first time to simultaneously determine hyperoside and 2′′–O‐galloylhyperin, two major components in Pyrola calliantha extract, in rat plasma. Following extraction by one‐step protein precipitation with methanol, the analytes were separated on a Venusil MP‐C₁₈ column within 2 min, using methanol–water–formic acid (50:50:0.1, v/v/v) as the mobile phase at a flow rate of 0.4 mL/min. Detection was performed on electrospray negative ionization mass spectrometry by multiple‐reaction monitoring of the transitions of 2′′–O‐galloylhyperin at m/z 615.1 → 301.0, of hyperoside at m/z 463.1 → 300.1, and of internal standard at m/z 415.1 → 295.1. The limits of quantification were 2 ng/mL for both hyperoside and 2′′–O‐galloylhyperin. The precisions were <13.1%, and the accuracies were between ?9.1 and 5.5% for both compounds. The method was successfully applied in pharmacokinetic studies following intravenous administration of the total flavonoids of P. calliantha extract in rats. Copyright © 2013 John Wiley & Sons, Ltd.     

Mechanisms of pharmacokinetic interaction between propranolol and quinidine in rats.

In order to study the mechanism of propranolol-quinidine interaction, the effects of quinidine on propranolol pharmacokinetics were examined in male Wistar rats. The concurrent oral administration of quinidine (10 mg/kg) markedly increased the plasma concentration of propranolol (2.5 mg/kg), and the area under the propranolol concentration-time curve increased about 3.6-fold. These results are consistent with previous observations in man and indicate the possible usefulness of the male Wistar rat as an animal model for investigating the mechanisms of the drug interaction. When propranolol was given intravenously, a concurrent administration of quinidine increased the apparent distribution volume of propranolol, mainly by decreasing its plasma protein binding. However, the systemic clearance of propranolol was not significantly altered by quinidine. Thus, quinidine increased the availability of oral propranolol from 13.8 +/- 2.2 to 44.2 +/- 4.6% (p less than 0.01). Furthermore, quinidine delayed the elimination of propranolol from the isolated perfused rat liver. These results indicate that quinidine reduces the presystemic elimination of propranolol in the liver, thereby increasing its systemic availability after oral administration.     

Learning size-adaptive molecular substructures for explainable drug–drug interaction prediction by substructure-aware graph neural network

Drug–drug interactions (DDIs) can trigger unexpected pharmacological effects on the body, and the causal mechanisms are often unknown. Graph neural networks (GNNs) have been developed to better understand DDIs. However, identifying key substructures that contribute most to the DDI prediction is a challenge for GNNs. In this study, we presented a substructure-aware graph neural network, a message passing neural network equipped with a novel substructure attention mechanism and a substructure–substructure interaction module (SSIM) for DDI prediction (SA-DDI). Specifically, the substructure attention was designed to capture size- and shape-adaptive substructures based on the chemical intuition that the sizes and shapes are often irregular for functional groups in molecules. DDIs are fundamentally caused by chemical substructure interactions. Thus, the SSIM was used to model the substructure–substructure interactions by highlighting important substructures while de-emphasizing the minor ones for DDI prediction. We evaluated our approach in two real-world datasets and compared the proposed method with the state-of-the-art DDI prediction models. The SA-DDI surpassed other approaches on the two datasets. Moreover, the visual interpretation results showed that the SA-DDI was sensitive to the structure information of drugs and was able to detect the key substructures for DDIs. These advantages demonstrated that the proposed method improved the generalization and interpretation capability of DDI prediction modeling.

SA-DDI is designed to learn size-adaptive molecular substructures for drug–drug interaction prediction and can provide explanations that are consistent with pharmacologists.     

Quantification of β‐eudesmol in rat plasma using LC–MS/MS and its application to a pharmacokinetic study

A sensitive and specific LC–MS/MS assay for determination of β ‐eudesmol in rat plasma was developed and validated. After liquid–liquid extraction with ethyl ether , the analyte and IS were separated on a Capcell Pak C₁₈ column (50 × 2.0 mm, 5 μm) by isocratic elution with acetonitrile—water–formic acid (77.5:22.5:0.1, v /v/v) as the mobile phase at a flow rate of 0.4 mL/min. An ESI source was applied and operated in positive ion mode; a selected reaction monitoring scan was used for quantification by monitoring the precursor–product ion transitions of m/z 245.1 → 163.1 for β ‐eudesmol and m/z 273.4 → 81.2 for IS. Good linearity was observed in the concentration range of 3–900 ng/mL for β ‐eudesmol in rat plasma. Intra‐ and inter‐day precision and accuracy were both within ±14.3%. This method was applied for pharmacokinetic studies after intravenous bolus of 2.0 mg/kg or intragastric administration of 50 mg/kg β ‐eudesmol in rats.     

Research on drug–receptor interactions and prediction of drug activity via oriented immobilized receptor capillary electrophoresis

Oriented covalent immobilized β₂‐adrenergic receptor (β₂‐AR) CE (OIRCE) was developed to determine the interactions between a set of natural extracts of Radix Paeoniae Rubra (NERPR) and β₂‐AR, and to predict the activity of NERPR. The inner capillary surface is chemically bonded with stable β₂‐AR coating via microwave‐assisted technical synthesis. The modified capillaries were characterized via infrared spectroscopy and fluorescence microscopy. Furthermore, the bonding amounts of β₂‐AR were first obtained via fluorescence spectroscopy method. In determining the amount of bonded β₂‐AR, the regression equation A  =  576 707C + 35.449 and the correlation coefficient 0.9995 were obtained. This result revealed an excellent linear relationship in the range of 2 × 10^?4 mg/mL to 1 × 10^?3 mg/mL. The normalized capacity factor (K_RCE) was obtained using OIRCE in evaluating drug–receptor interactions. Related theories and equations were used to calculate K_RCE values from apparent migration times of a solute and EOF. The order of K_RCE and the binding constant (K_b) values between drugs and β₂‐AR was well consistent. The results confirmed that the OIRCE and K_RCE values can be effectually used to investigate drug‐receptor interactions, and OIRCE has the potential to predict drug activity and to select leading compounds from natural chemicals.