Analytical sample preparation strategies for the determination of antimalarial drugs in human whole blood, plasma and urine

Lab-in-syringe automated protein precipitation and salting-out homogenous liquid-liquid extraction coupled online to UHPLC-MS/MS for the determination of beta-blockers in serum

A sample preparation method involving tandem implementation of protein precipitation and salting-out homogenous liquid-liquid extraction was developed for the determination of beta-blockers in serum. The entire procedure was automated using a computer-controlled syringe pump following the Lab-In-Syringe approach. It is based on the denaturation of serum proteins with acetonitrile followed by salt-induced phase separation upon which the proteins accumulate as a compact layer at the interphase of the solutions. The extract is then separated and diluted in-syringe before being submitted to online coupled UHPLC-MS/MS. A 1 mL glass syringe containing a small stir bar for solution mixing at up to 3000 rpm, was used to deal with sample volumes as small as 100 μL. A sample throughput of 7 h^-1 was achieved by performing the chromatographic run and sample preparation procedure in parallel. Linear working ranges were obtained for all analytes between 5 and 100 ng mL^-1, with LOD values ranging from 0.4 to 1.5 ng mL^-1. Accuracy values in the range of 88.2-106% and high precision of <11% RSD suggest applicability for routine analysis that can be further improved using deuterated standards.

Determination of antimalarial drugs in pharmaceutical formulations and human blood by liquid chromatography: a review

Malaria is a life-threatening disease being treated by oral medication. This is the best treatment to reduce morbidity and mortality, prevent disease progression to the most severe form, lower the transmission of the disease and hinder the appearance of strains resistant to antimalarials. According to the World Health Organization, the most common antimalarial drugs are chloroquine, primaquine, mefloquine, lumefantrine, artemether, and artesunate in single dosage forms or fixed-dose combination. Within this context, the present review aims to show the evolution of different analytical methods that have been applied to the determination of these antimalarial drugs in pharmaceutical formulations and human blood by liquid chromatography in the last 10 years, along with statistical analyses of the methods.

Application of curcumin as a green and new sorbent in deep eutectic solvent-based dispersive micro-solid phase extraction of several polycyclic aromatic hydrocarbons from honey samples prior to gas chromatography-mass spectrometry determination

A green, simple, and efficient dispersive micro-solid phase extraction method was developed for the extraction of polycyclic aromatic hydrocarbons from honey samples. In this method, for the first time, curcumin was used as an efficient and green sorbent to extract the analytes from the sample. After that the adsorbed analytes were eluted using a deep eutectic solvent prepared by mixing tetrabutylammonium chloride: ethylene glycol and analyzed by gas chromatography-mass spectrometry. Important experimental factors affecting adsorption and desorption steps of the method were optimized and under optimal experimental conditions, low limits of detection (0.14-0.37 ng/g) and quantification (0.49-1.3 ng/g), wide linear range (1.3-500 ng/g) with a coefficient of determination ≥0.994 were obtained. Relative standard deviation values for intra- and interday precisions were ≤7.5% for all of the analytes at a concentration of 2 ng/g for each analyte (n = 6). Extraction recovery of the method was in the range of 72-81%. Finally, 20 honey samples were analyzed and the analytes were successfully detected. The method is environment friendly because of the use of curcumin as a sorbent. Also, biodegradability of the used deep eutectic solvent components is another advantage of the method.

Quantitative microsampling for bioanalytical applications related to the SARS-CoV-2 pandemic: Usefulness, benefits and pitfalls

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SARS-CoV-2 emergency sparks the need for diagnostic and therapeutic actions.

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Microsampling is emerging in as an attractive alternative to traditional sampling.

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Advantages and challenges of the main microsampling techniques are reported.

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Available microsampling applications of interest for SARS-CoV-2 are described.

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Most useful information for researchers and clinicians are gathered and provided.

The multiple pathological effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and its total novelty, mean that currently a lot of diagnostic and therapeutic tools, established and tentative alike, are needed to treat patients in a timely, effective way. In order to make these tools more reliable, faster and more feasible, biological fluid microsampling techniques could provide many advantages. In this review, the most important microsampling techniques are considered (dried matrix spots, volumetric absorptive microsampling, microfluidics and capillary microsampling, solid phase microextraction) and their respective advantages and disadvantages laid out. Moreover, currently available microsampling applications of interest for SARS-CoV-2 therapy are described, in order to make them as much widely known as possible, hopefully providing useful information to researchers and clinicians alike.

Quantitative determination of the antimalarials artemether and lumefantrine in biological samples: A review

Malaria is a worldwide health issue, with 216 million cases reported in 2016. Due to the widespread resistance of Plasmodium falciparum to conventional drugs, the first line treatment recommended by World Health Organization for uncomplicated malaria is artemisinin-based combined therapy (ACT), which combines two drugs with different mechanisms of action. The association of artemether and lumefantrine is the most common ACT used in the clinical practice. However, there have been reports of clinical artemisinin and derivatives partial resistance, which is defined as delayed parasite clearance. In this context, the monitoring of drug concentration in biological matrices is essential to evaluate treatment response, the need of dose adjustment and the occurrence of dose dependent adverse effects. Furthermore, it is also important for pharmacokinetic studies and in the development of generic and similar drugs. Determination of antimalarial drugs in biological matrices requires a sample pre-treatment, which involves drug extraction from the matrix and analyte concentration. The most used techniques are protein precipitation (PP), liquid-liquid extraction (LLE) and solid phase extraction (SPE). Subsequently, a liquid chromatography step is usually applied to separate interferences that could be extracted along with the analyte. Finally, the analytes are detected employing techniques that must be selective and sensitive, since the analyte might be present in trace levels. The most used approach for detection is tandem mass spectrometry (MS-MS), but ultraviolet (UV) is also employed in several studies. In this article, a review of the scientific peer-review literature dealing with validated quantitative analysis of artemether and/or lumefantrine in biological matrices, from 2000 to 2018, is presented.

LC-MS/MS method for the simultaneous analysis of seven antimalarials and two active metabolites in dried blood spots for applications in field trials: Analytical and clinical validation

In epidemiological studies, antimalarials measurements in blood represent the best available marker of drugs exposure at population level, an important driver for the emergence of drug resistance. We have developed a liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for the simultaneous quantification of 7 frequently used antimalarials (amodiaquine, chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine) and 2 active metabolites (N-desethyl-amodiaquine, desbutyl-lumefantrine) in 10-μl dried blood spots (DBS). This sampling approach is suitable for field studies wherein blood samples processing, transportation and storage are problematic. Sample preparation included extraction from a 3 mm-disk punched out of the DBS with 100-μl of methanol + 1% formic acid containing deuterated internal standards for all drugs. Good performances were achieved in terms of trueness (-12.1 to +11.1%), precision (1.4-15.0%) and sensitivity, with lower limits of quantification comprised between 2 ng/ml (sulfadoxine) and 20 ng/ml (chloroquine, quinine, pyrimethamine, mefloquine, lumefantrine and desbutyl-lumefantrine). All analytes were stable in DBS kept for 24 h at room temperature and at 37 °C. The developed assay was applied within the frame of a pharmacokinetic study including 16 healthy volunteers who received a single dose of artemether-lumefantrine. Lumefantrine concentrations in plasma and in DBS were highly correlated (R = 0.97) at all time points, confirming the assumption that lumefantrine concentrations determined in DBS confidently reflect blood concentrations. The blood/plasma ratio of 0.56 obtained using the Bland-Altman approach (and corresponding to the slope of the linear regression) is in line with very low penetration of lumefantrine into red blood cells. This sensitive multiplex LC-MS/MS assay enabling the simultaneous analysis of antimalarials in DBS is suitable for epidemiological studies in field conditions.

Deproteinization assessment using isotopically enriched compounds to trace the coprecipitation of low-molecular-weight selenium species with proteins

Studies have shown that information related to the presence of low-molecular-weight metabolites is frequently lost after deproteinization of complex matrices, such as blood and plasma, during sample preparation. Therefore, the effect of several deproteinization reagents on low-molecular-weight selenium species has been compared by species-specific isotope labeling. Two isotopically enriched selenium tracers were used to mimic models of small inorganic anionic (⁷⁷Se-selenite) and organic zwitterionic (⁷⁶Se-selenomethionine) species. The results presented here show that the use of a methanol-acetonitrile-acetone (1:1:1 v/v/v) mixture provided approximately two times less tracer loss from plasma samples in comparison with the classic procedure using acetonitrile, which may not be optimal as it leads to important losses of low-molecular-weight selenium species. In addition, the possible interactions between selenium tracers and proteins were investigated, revealing that both coprecipitation phenomena and association with proteins were potentially responsible for selenite tracer losses during protein precipitation in blood samples. However, coprecipitation phenomena were found to be fully responsible for losses of both tracers observed in plasma samples and of the selenomethionine tracer in blood samples. This successfully applied strategy is anticipated to be useful for more extensive future studies in selenometabolomics.

Development of a simple and sensitive HPLC-UV method for the simultaneous determination of cannabidiol and Δ(9)-tetrahydrocannabinol in rat plasma

There has been increased interest in the medical use of cannabinoids in recent years, particularly in the predominant natural cannabinoids, cannabidiol (CBD) and Δ(9)-tetrahydrocannabinol (THC). The aim of the current study was to develop a sensitive and reliable method for the quantification of CBD and THC in rat plasma. A combination of protein precipitation using cold acetonitrile and liquid-liquid extraction using n-hexane was utilised to extract CBD and THC from rat plasma. Samples were then evaporated and reconstituted in acetonitrile and 30 μL was injected into an HPLC system. Separation was achieved using an ACE C18-PFP 150 mm × 4.6 mm, 3 μm column at 55 °C with isocratic elution using a mobile phase consisting of acetonitrile-water (62:38, v/v) at 1 mL/min for 20 min. Both cannabinoids, as well as the internal standard (4,4-dichlorodiphenyltrichloroethane, DDT) were detected at 220 nm. Our new method showed linearity in the range of 10-10,000 ng/mL and a lower limit of quantification (LLOQ) of 10 ng/mL for both cannabinoids, which is comparable to previously reported LC-MS/MS methods. Inter- and intra-day precision and accuracy were below 15% RSD and RE, respectively. To demonstrate the suitability of the method for in vivo studies in rats, the assay was applied to a preliminary pharmacokinetic study following IV bolus administration of 5 mg/kg CBD or THC. In conclusion, a simple, sensitive, and cost-efficient HPLC-UV method for the simultaneous determination of CBD and THC has been successfully developed, validated and applied to a pharmacokinetic study in rats.