Direct injection human plasma analysis for the quantification of antihypertensive drugs for therapeutic drug monitoring using hydrophilic interaction liquid chromatography/electrospray ionization mass spectrometry

Rapid methylation of valsartan in human plasma using evaporative derivatization reagent to improve its sensitivity in MALDI-TOF mass spectrometry

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a rapid and low-solvent-consumption technique. However, almost every mass in the low mass-to-charge-ratio region of the mass spectrum appears as strongly fluctuating matrix background signals. Thus, it is difficult to identify small molecules using this technique. In this study, we used methanol to methylate valsartan, an angiotensin II receptor blocker that is commonly used to treat high blood pressure and heart failure. The methylation derivatization of valsartan enhanced the detection sensitivity and transformed the detection m/z ratio. The liquid-phase microextraction of valsartan in human plasma (20 μL) was achieved by acidifying valsartan with HCl aqueous solution and extracting it with toluene. An acetyl chloride/anhydrous methanol mixture was added for methylation derivatization, which was completed within 30 min at 30 °C. Finally, the residue was re-dissolved in irbesartan methanolic solution, which together with the matrix 2-mercaptobenzothiazole was spotted on an AnchorChip target plate for MALDI-TOF MS analysis. Liquid-phase microextraction was performed and the methylation-derivatization parameters were investigated. The valsartan calibration range was 0.2-10 μg mL^-1 with good linearity in human plasma. In the within- and between-run analyses, the relative standard deviation and relative error were both <11.32%. This method was successfully applied to determine the valsartan concentration in the plasma of 10 patients with hypertension.

Hydrophilic Interaction Liquid Chromatography (HILIC): Latest Applications in the Pharmaceutical Researches

Background:

Significant advances have been occurred in analytical research since the 1970s by Liquid Chromatography (LC) as the separation method. Reverse Phase Liquid Chromatography (RPLC) method, using hydrophobic stationary phases and polar mobile phases, is the most commonly used chromatographic method. However, it is difficult to analyze some polar compounds with this method. Another separation method is the Normal Phase Liquid Chromatography (NPLC), which involves polar stationary phases with organic eluents. NPLC presents low-efficiency separations and asymmetric chromatographic peak shapes when analyzing polar compounds. Hydrophilic Interaction Liquid Chromatography (HILIC) is an interesting and promising alternative method for the analysis of polar compounds. HILIC is defined as a separation method that combines stationary phases used in the NPLC method and mobile phases used in the RPLC method. HILIC can be successfully applied to all types of liquid chromatographic separations such as pharmaceutical compounds, small molecules, metabolites, drugs of abuse, carbohydrates, toxins, oligosaccharides, peptides, amino acids and proteins.

Objective:

This paper provides a general overview of the recent application of HILIC in the pharmaceutical research in the different sample matrices such as pharmaceutical dosage form, plasma, serum, environmental samples, animal origin samples, plant origin samples, etc. Also, this review focuses on the most recent and selected papers in the drug research from 2009 to the submission date in 2020, dealing with the analysis of different components using HILIC.

Results and Conclusion:

The literature survey showed that HILIC applications are increasing every year in pharmaceutical research. It was found that HILIC allows simultaneous analysis of many compounds using different detectors.

A simple and sensitive HPLC-FL method for simultaneous determination of angiotensin II receptor antagonists in human plasma

Angiotensin II receptor antagonists are one of the most widely used classes of antihypertensive drugs. In this study, an HPLC fluorescence method after protein precipitation (PPT) extraction was developed and validated for determination of olmesartan, losartan, irbesartan, and valsartan in human plasma. The separation was carried out on a Luna cyano (250 × 4.6 mm i.d.; 5 μm particle size) column and the mobile phase was composed of acetonitrile and 0.1 % phosphoric acid in gradient elution, at a flow rate of 1.2 mL min^-1. A PPT method was optimized by a two-level factorial design with triplicate at the central point. The parameters that could affect the extraction (sample volume and acetonitrile/plasma volume ratio) were evaluated and the method was compared to microextraction by packed sorbent (MEPS) and liquid-liquid extraction (LLE). The developed method allowed the simultaneous quantification of the analytes employing a simple and cheap sample preparation method and a short chromatographic run (13 min). This method was fully validated showing selectivity, precision, accuracy, and linearity over the range of 25.0-1500.0 ng mL^-1 for olmesartan and valsartan, 25.0-2500.0 ng mL^-1 for irbesartan, and 35.0-2500.0 ng mL^-1 for losartan. Finally, the method was successfully applied in the analysis of human plasma from volunteers.

Integrated Analytical Quality by Design (AQbD) Approach for the Development and Validation of Bioanalytical Liquid Chromatography Method for Estimation of Valsartan

The present studies describe the systematic development and validation of a simple, rapid, sensitive and cost-effective reversed-phase high-performance liquid chromatographic bioanalytical method for the estimation of valsartan in rat plasma employing analytical quality by design (AQbD) principles quality risk management was applied for identifying the critical method parameters (CMPs) and subsequently method optimization was performed employing Box–Behnken design by selecting mobile phase pH, flow rate and % organic modifier as the CMPs and evaluated for critical analytical attributes (CAAs) such as peak area, retention time, peak tailing and number of theoretical plates. The developed method was then transferred to bioanalysis, where liquid–liquid extraction process was used for separating the drug from rat plasma. The optimization of extraction process was performed with the help of face-centered cubic design by selecting centrifugation speed and centrifugation time as the CMPs for maximizing % recovery, signal-to-noise ratio and purity threshold of the drug peak after extraction as the CAAs. Optimum chromatographic solution was chosen by mathematical and graphical search techniques, and design space was demarcated. Validation studies performed for the developed method indicated linearity ranging between 5 and 100 ng.mL−1, whereas accuracy and precision study showed good percent recovery (99–102%) along with % relative standard deviation within ±2%. Sensitivity evaluation revealed limit of detection and limit of quantification were found to be 0.76 ng.mL−1 and 2.29 ng.mL−1, respectively. In a nutshell, the present work demonstrates significant merits of AQbD approach for holistic process understanding and analytical method development and validation with enhanced robustness and performance.

UHPLC-MS/MS method with protein precipitation extraction for the simultaneous quantification of ten antihypertensive drugs in human plasma from resistant hypertensive patients

Today the management of resistant hypertension is a critical health problem: the main difficulty on this field is the discrimination of cases of poor therapeutic adherence from cases of real resistance. This gives rise to the need of high throughput and reliable quantification methods for the Therapeutic Drug Monitoring (TDM) of antihypertensive drugs. The aim of this work was the development and validation of a UHPLC-Tandem mass spectrometry assay for this application and its use in plasma from patients with resistant hypertension. The novelty of this method resides in the ability to simultaneously quantify a wide panel of antihypertensive drugs: amlodipine, atenolol, clonidine, chlortalidone, doxazosin, hydrochlorothiazide, nifedipine, olmesartan, ramipril and telmisartan. Moreover, this method stands out for its simplicity and cheapness, resulting feasible for clinical routine. Both standards and quality controls were prepared in human plasma. After the addition of internal standard, each sample underwent protein precipitation with acetonitrile and was then dried. Extracts were resuspended in water:acetonitrile 90:10 (0.05% formic acid) and then injected into the chromatographic system. Chromatographic separation was performed on an Acquity(®) UPLC HSS T3 1.8μm 2.1×150mm column, with a gradient of water and acetonitrile, both added with 0.05% formic acid. Accuracy, intra-day and inter-day precision fitted FDA guidelines for all analytes, while matrix effects and recoveries resulted stable between samples for each analyte. Finally, we tested this method by monitoring plasma concentrations in 22 hypertensive patients with good results. This simple analytical method could represent a useful tool for the management of antihypertensive therapy.

Doping control analysis of 46 polar drugs in horse plasma and urine using a 'dilute-and-shoot' ultra high performance liquid chromatography-high resolution mass spectrometry approach

The high sensitivity of ultra high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS) allows the identification of many prohibited substances without pre-concentration, leading to the development of simple and fast 'dilute-and-shoot' methods for doping control for human and equine sports. While the detection of polar drugs in plasma and urine is difficult using liquid-liquid or solid-phase extraction as these substances are poorly extracted, the 'dilute-and-shoot' approach is plausible. This paper describes a 'dilute-and-shoot' UHPLC-HRMS screening method to detect 46 polar drugs in equine urine and plasma, including some angiotensin-converting enzyme (ACE) inhibitors, sympathomimetics, anti-epileptics, hemostatics, the new doping agent 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), as well as two threshold substances, namely dimethyl sulfoxide and theobromine. For plasma, the sample (200μL) was protein precipitated using trichloroacetic acid, and the resulting supernatant was diluted using Buffer A with an overall dilution factor of 3. For urine, the sample (20μL) was simply diluted 50-fold with Buffer A. The diluted plasma or urine sample was then analysed using a UHPLC-HRMS system in full-scan ESI mode. The assay was validated for qualitative identification purpose. This straightforward and reliable approach carried out in combination with other screening procedures has increased the efficiency of doping control analysis in the laboratory. Moreover, since the UHPLC-HRMS data were acquired in full-scan mode, the method could theoretically accommodate an unlimited number of existing and new doping agents, and would allow a retrospectively search for drugs that have not been targeted at the time of analysis.