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

Determination of sulfadoxine and pyrimethamine in microvolume human plasma using ultra high performance liquid chromatography-tandam mass spectrometry

To support the pharmacokinetic study of sulfadoxine (SD) and pyrimethamine (PM) in pregnant women and children, sensitive methods with small sample volume are desirable. Here we report a method to determine SD and PM with microvolume plasma samples: 5 µL plasma samples were cleaned up by protein precipitation with acetonitrile. The deuterated analytes were used as the internal standards. The samples after cleanup were injected onto an ACE Excel SuperC18 column (50 × 2.1 mm, 1.7 μm, Hichrom Limited) connected to a Waters I class UPLC coupled with a Sciex Triple Quad 6500+ Mass Spectrometer and eluted with water and acetonitrile both containing 0.1% formic acid in a gradient mode at 0.8mL/min. Detection utilized ESI+ as the ion source and MRM as the quantification mode. The precursor-to-product ion transitions m/z 311→245 for SD and 249→233 for PM were selected for quantification. The ion transitions for the corresponding internal standards were 315→249 for SD-d4 and 254→235 for PM-d3. The simplest linear regression weighted by 1/x was used for the calibration curves. The calibration ranges were 1-200 µg/mL SD and 2 - 1000ng/mL PM. The mean (± standard deviation) recoveries were 94.3±3.2% (SD) and 97.0±1.5% (PM). The validated method was applied to analysis of 1719 clinical samples, demonstrating the method is suitable for the pharmacokinetic study with samples collected up to day 28 post-dose.

Clinical needs assessment to inform development of a new assay to detect antimalarial drugs in patient samples: A case study

Point-of-care assays have greatly increased access to diagnostic information and improved healthcare outcomes globally, especially in the case of tropical diseases in rural settings. Increased recognition of the impact of these tools and increased funding, along with advances in technology have led to a surge in development of new assays. However, many new tools fail to fulfill their intended purpose due to a lack of clinical impact, operational feasibility, and input from envisioned operators. To be successful, they must fit into existing clinical decision-making models and be designed in collaboration with end users. We describe a case study of the development of a new low-cost sensor for antimalarial drugs, from initial planning through collection and incorporation of design feedback to final assay design. The assay uses an aptamer-based sensor to detect antimalarial drugs from patient samples for tracking antimalarial use in Southeast Asia, a region with a long history of emerging antimalarial drug resistance. Design and use-case input was collected from malaria control experts, researchers, and healthcare workers to develop target product profiles. Data was collected via surveys and in-person interviews during assay development and ultimately informed a change in assay format. This aptamer sensor platform can be easily adapted to detect other small molecule and protein targets and the design process described here can serve as a model for the development of effective new assays to improve access to healthcare technology.

Estimation of dihydroartemisinin in human plasma using a highly sensitive LTQ Orbitrap mass spectrometer with Xcalibur software

Background: Artemether (ARM), the O-methyl ether prodrug of dihydroartemisinin (DHA), is considered a first-line antimalarial agent. Artemether is extensively metabolized in vivo to its active metabolite DHA, and therefore its determination offers considerable difficulties. In the present study, DHA identification and estimation were accurately performed by the mass spectrometric analysis, using a high-resolution liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) LTQ Orbitrap hybrid mass spectrometer. Methods: The plasma samples were taken from healthy volunteers, and the spiked plasma was extracted by adding 1 mL of a mixture of dichloromethane and tert.-methyl butyl ether (8:2 v/v) to 0.5 mL of plasma. The internal standard solution (artemisinin 500 ng/mL) was added to the plasma samples. After vertexing and centrifugation, the organic layer was separated and transferred into another tube and dried under nitrogen. The residue was reconstituted in 100 μL of acetonitrile and was injected onto the LC-MS system for analysis. Measurement of standards and samples was carried out isocratically on a Surveyor HPLC system combined with an LTQ Orbitrap mass spectrometer using an ACE 5 C18-PFP column. Mobile phase A consisted of 0.1% v/v formic acid in water, Mobile phase B consisted of acetonitrile only, and isocratic elution was carried out with A:B 20:80, v/v. The flow rate was 500 μL/min. The ESI interface was operated in a positive ion mode with a spray voltage of 4.5 kV. Results: Artemether is not a very biologically stable compound and is immediately metabolized to its active metabolite dihydroartemisinin, so no clear peak was observed for artemether. Both artemether and DHA after ionization undergo neutral losses of methanol and water, respectively, in the source of the mass spectrometer. The ions observed were (MH-H₂O) m/z 267.15 for DHA and (MH-m/z 283.15 for internal standard artemisinin. The method was validated according to international guidelines. Discussion: The validated method was applied successfully for the determination and quantification of DHA in plasma samples. This method works well for the extraction of drugs, and the Orbitrap system with the help of Xcalibur software accurately and precisely determines the concentration of DHA in spiked as well as volunteer's plasma.

Whole sporozoite immunization with Plasmodium falciparum strain NF135 in a randomized trial

BACKGROUND

Whole sporozoite immunization under chemoprophylaxis (CPS regime) induces long-lasting sterile homologous protection in the controlled human malaria infection model using Plasmodium falciparum strain NF54. The relative proficiency of liver-stage parasite development may be an important factor determining immunization efficacy. Previous studies show that Plasmodium falciparum strain NF135 produces relatively high numbers of large liver-stage schizonts in vitro. Here, we evaluate this strain for use in CPS immunization regimes.

METHODS

In a partially randomized, open-label study conducted at the Radboudumc, Nijmegen, the Netherlands, healthy, malaria-naïve adults were immunized by three rounds of fifteen or five NF135-infected mosquito bites under mefloquine prophylaxis (cohort A) or fifteen NF135-infected mosquito bites and presumptive treatment with artemether/lumefantrine (cohort B). Cohort A participants were exposed to a homologous challenge 19 weeks after immunization. The primary objective of the study was to evaluate the safety and tolerability of CPS immunizations with NF135.

RESULTS

Relatively high liver-to-blood inocula were observed during immunization with NF135 in both cohorts. Eighteen of 30 (60%) high-dose participants and 3/10 (30%) low-dose participants experienced grade 3 adverse events 7 to 21 days following their first immunization. All cohort A participants and two participants in cohort B developed breakthrough blood-stage malaria infections during immunizations requiring rescue treatment. The resulting compromised immunizations induced modest sterile protection against homologous challenge in cohort A (5/17; 29%).

CONCLUSIONS

These CPS regimes using NF135 were relatively poorly tolerated and frequently required rescue treatment, thereby compromising immunization efficiency and protective efficacy. Consequently, the full potential of NF135 sporozoites for induction of immune protection remains inconclusive. Nonetheless, the high liver-stage burden achieved by this strain highlights it as an interesting potential candidate for novel whole sporozoite immunization approaches.

TRIAL REGISTRATION

The trial was registered at ClinicalTrials.gov under identifier NCT03813108.

Optimization of HPLC-MS/MS method for determination of antimalarial adulterants in herbal products

The use of herbal products is booming all over the world because of being believed as safer than conventional drugs and free of side effects. However, there are untrustworthy manufacturers who adulterate herbal products by adding conventional drugs which might eventually lead to microbial resistance and herb-to-drug interactions. There is a need to develop methods for detecting adulterants in herbal products. A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for simultaneous identification and determination of conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products was developed. Stable isotopically labelled compounds (artemether-d₃, quindine-d₃, and sulfadoxine-d₃) were used as internal standards (ISs) for quantitative analysis. Extraction of analytes was performed using methanol: water: formic acid (90:10:0.1, v/v) and chromatographic separation was done in a gradient mode using mobile phase A: Ultrapure water containing 0.1% formic acid and 1 mM ammonium formate and mobile phase B: Acetonitrile/methanol (50:50) containing 0.1% formic acid and 1 mM ammonium formate. The calibration curves were linear (r² ≥ 0.991) over the range of 0.001-0.3 µg mL^-1 for all compounds. The limit of detection (LOD) ranged from 0.002 to 0.02 μg mL^-1 while the limit of quantification (LOQ) ranged from 0.006 to 0.08 μg mL^-1. Accuracy, expressed as recovery of spiked herbal products ranged from 52 to 128%. The precision, expressed as percent relative standard deviation (%RSD) at two concentration levels, ranged from 1.0 to 13.8%. The matrix effect expressed as the matrix factor (MF) ranged from 0.77 to 0.97. The developed method was used to identify and quantify conventional antimalarials in herbal product samples from Tanzania. Ten out of 50 herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine. The developed method is considered a valuable tool for getting a better understanding of the adulteration of conventional antimalarials in herbal products.

Direct multiclass desorption electrospray ionization-tandem mass spectrometry method for the analysis of sleep inducers and ototoxic drugs in dried blood spots

RATIONALE

An unconventional and innovative approach for the quantitative determination of 11 ototoxic and narcoleptic drugs in whole blood is described. The multiclass method allows the inclusion of the most widespread drugs on the market (antihistamines, antidepressants, antihypertensives, anxiolytics, opioids, Z-drugs) responsible for 10% of occupational accidents.

METHODS

The developed procedure involved the use of the desorption electrospray ionization (DESI) interface for the direct analysis of dried blood spots (DBS). All the issues strictly connected to the chemical-physical characteristics of DBS and DESI (sample inhomogeneity, DBS support, DESI geometry and solvent) were carefully evaluated and innovative strategies were applied. Haematocrit was managed using a small and measured volume of blood (2 μL) with analysis of the entire DBS.

RESULTS

The proposed method was fully validated in terms of limits of detection, limits of quantitation (LOQs; between 60 pg/mm² and 1.6 ng/mm² ), linearity (one order of magnitude starting from LOQs) and inter- and intra-day precision (on three levels, with relative standard deviation values not exceeding 17%). Accuracy was calculated by comparison with an ultrahigh-performance liquid chromatography-tandem mass spectrometry method (suitable also as a confirmatory method).

CONCLUSIONS

Results showed a surprising sensitivity, demonstrating that this procedure could be suitable for applications in various fields, e.g. forensic analysis. Moreover, as a collateral benefit, it was discovered that the method is able to analyse very light traces left on plastic and glass surfaces by detached dried blood.

Analytical Methods for the Determination of Major Drugs Used for the Treatment of COVID-19. A Review

At the beginning of the COVID-19 outbreak (end 2019 - 2020), therapeutic treatments based on approved drugs have been the fastest approaches to combat the new coronavirus pandemic. Nowadays several vaccines are available. However, the worldwide vaccination program is going to take a long time and its success will depend on the vaccine public's acceptance. Therefore, outside of vaccination, the repurposing of existing antiviral, anti-inflammatory and other types of drugs, have been considered an alternative medical strategy for the COVI-19 infection. Due to the broad clinical potential of the drugs, but also to their possible side effects, analytical methods are needed to monitor the drug concentrations in biological fluids and pharmaceutical products. This review deals with analytical methods developed in the period 2015 - July 2021 to detect potential drugs that, according to a literature survey, have been taken into consideration for the treatment of COVID-19. The drugs considered here have been selected on the basis of the number of articles published in the period January 2020-July 2021, using the combination of the keywords: COVID-19 and drugs or SARS-CoV-2 and drugs. A section is also devoted to monoclonal antibodies. Over the period considered, the analytical methods have been employed in a variety of real samples, such as body fluids (plasma, blood and urine), pharmaceutical products, environmental matrices and food.

Development of single- and multiplex immunoassays for rapid detection and quantitation of amodiaquine in ACT drugs and rat serum

Amodiaquine (AQ) is a commonly used antimalarial drug, and N-desethyl-AQ (N-DEAQ) is an active metabolite of AQ. Given the significance of drug quality in the management of malaria cases, this study aims to develop antibody-based assays for the detection and quantitation of AQ without the need for sophisticated equipment. Two monoclonal antibodies (mAbs) against AQ, designated as JUN7 and TE7, were selected, which showed 72.7% and 9.5% cross-reactivity to N-DEAQ, respectively. These mAbs showed <0.1% cross-reactivity to other commonly used antimalarial drugs. An indirect competitive enzyme-linked immunosorbent assay (icELISA) based on JUN7 showed a 50% inhibitory concentration (IC50) of 0.16 ng/mL and a working range of 0.06-0.46 ng/mL. A lateral flow immunoassay (LFIA) based on JUN7 was also developed with a working range of 2.58-30.86 ng/mL. The icELISA and LFIA were applied for the quantification of AQ in commercial drugs, and the results were comparable to those determined using high-performance liquid chromatography. In addition, a combination dipstick for simultaneous, qualitative analysis of AQ and artesunate was developed. All immunoassays based on JUN7 can be applied for quality control of AQ-containing artemisinin-based combination therapies. As TE7 showed low cross-reactivity to N-DEAQ, an icELISA based on TE7 was developed with an IC50 of 0.38 ng/mL and a working range of 0.14-1.67 ng/mL. The TE7 icELISA was applied for the study of pharmacokinetics of AQ in rat serum after intragastric administration, and the results were consistent with those of previous studies.

Development and application of immunoassays for rapid quality control of the antimalarial drug combination artesunate-mefloquine

Artesunate-mefloquine is one of the commonly-used artemisinin-based combination therapies (ACTs). Given the significance of drug quality in the management of malaria cases, the objective of this study was to develop antibody-based assays as the point-of-care (POC) tests for monitoring the quality of this ACT. Using mefloquine conjugated to a carrier protein as the immunogen, we selected a specific monoclonal antibody (mAb) against mefloquine with no cross-reactivity to other antimalarial drugs. Using this mAb, we developed a direct competitive enzyme-linked immunosorbent assay (dcELISA) and a lateral flow immunoassay (LFIA) to measure the mefloquine contents. The dcELISA for mefloquine showed a 50% inhibitory concentration (IC₅₀) and a working range of 2.79 ng/mL and 0.58-16.37 ng/mL, respectively. With the aid of a portable optical scanner, the LFIA had a working range of 0.15-2.67 µg/mL for mefloquine. When used to measure mefloquine contents in commercial drugs, the dcELISA and LFIA results were compatible with those determined using high-performance liquid chromatography. Using the same LFIA format, we developed a combination LFIA, which correctly estimated the artesunate and mefloquine contents in commercial ACTs. Therefore, both LFIAs could be used as POC devices for rapid quality control of artesunate and mefloquine in ACTs.

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.

Liquid Chromatographic Methods for COVID-19 Drugs, Hydroxychloroquine and Chloroquine

COVID-19 has been a threat throughout the world since December 2019. In attempts to discover an urgent treatment regime for COVID-19, hydroxychloroquine (HCQ) and chloroquine (CQ) have been on solidarity clinical trial. However, many countries have pulled HCQ and CQ from their COVID-19 treatment regimens recently, some countries still continue using them for patients who have previously started HCQ and CQ and they may complete their course under the supervision of a doctor. HCQ and CQ are 4-aminoquinoline drugs and it is safe to use them for autoimmune diseases, rheumatoid arthritis, systemic lupus erythematosus and malaria as well. Determination of CQ, HCQ and their metabolites in biologic fluids and in pharmaceuticals has great importance, especially for pharmacokinetics, pharmacodynamics and epidemiological studies. In this review, liquid chromatographic methods developed in the last 10 years were summarized focusing on sample preparation and detection methods for HCQ and CQ determination in biological fluids and pharmaceutical preparations. It is hoped that this article could be helpful to facilitate the use of these drugs in clinical trials or drug research studies as it provides comprehensive information on the reported analytical methods.

Structure-switching aptamer sensors for the specific detection of piperaquine and mefloquine

Tracking antimalarial drug use and efficacy is essential for monitoring the current spread of antimalarial drug resistance. However, available methods for determining tablet quality and patient drug use are often inaccessible, requiring well-equipped laboratories capable of performing liquid chromatography-mass spectrometry (LC-MS). Here, we report the development of aptamer-based fluorescent sensors for the rapid, specific detection of the antimalarial compounds piperaquine and mefloquine-two slow-clearing partner drugs in current first-line artemisinin-based combination therapies (ACTs). Highly selective DNA aptamers were identified that bind piperaquine and mefloquine with dissociation constants (K _d's) measured in the low nanomolar range via two independent methods. The aptamers were isolated from a library of single-stranded DNA molecules using a capture-systematic evolution of ligands by exponential enrichment (SELEX) technique and then adapted into structure-switching aptamer fluorescent sensors. Sensor performance was optimized for the detection of drug from human serum and crushed tablets, resulting in two sensing platforms. The patient sample platform was validated against an LC-MS standard drug detection method in samples from healthy volunteers and patients with malaria. This assay provides a rapid and inexpensive method for tracking antimalarial drug use and quality for the containment and study of parasite resistance, a major priority for malaria elimination campaigns. This sensor platform allows for flexibility of sample matrix and can be easily adapted to detect other small-molecule drugs.

HPLC methods for choloroquine determination in biological samples and pharmaceutical products

OBJECTIVE

Review and assess pharmaceutical and clinical characteristics of chloroquine including high-performance liquid chromatography (HPLC)-based methods used to quantify the drug in pharmaceutical products and biological samples.

EVIDENCE ACQUISITION

A literature review was undertaken on the PubMed, Science Direct, and Scielo databases using the following keywords related to the investigated subject: 'chloroquine', 'analytical methods', and 'HPLC'.

RESULTS

For more than seven decades, chloroquine has been used to treat malaria and some autoimmune diseases, such as lupus erythematosus and rheumatoid arthritis. There is growing interest in chloroquine as a therapeutic alternative in the treatment of HIV, Q fever, Whipple's disease, fungal, Zika, Chikungunya infections, Sjogren's syndrome, porphyria, chronic ulcerative stomatitis, polymorphic light eruption, and different types of cancer. HPLC coupled to UV detectors is the most employed method to quantify chloroquine in pharmaceutical products and biological samples. The main chromatographic conditions used to identify and quantify chloroquine from tablets and injections, degradation products, and metabolites are presented and discussed.

CONCLUSION

Research findings reported in this article may facilitate the repositioning, quality control, and biological monitoring of chloroquine in modern pharmaceutical dosage forms and treatments.

Quadruple isotope dilution gas chromatography-mass spectrometry after simultaneous derivatization and spraying based fine droplet formation liquid phase microextraction method for the accurate and sensitive quantification of chloroquine phosphate in human serum, urine and saliva samples at trace levels

This study presents an accurate and precise analytical strategy for the determination of chloroquine phosphate at trace levels in human body fluids (urine, serum, and saliva). Simultaneous derivatization-spraying based fine droplet formation-liquid phase microextraction (SD-SFDF-LPME) method was used to derivatize and preconcentrate the analyte prior to gas chromatography-mass spectrometry (GC-MS) measurements. Acetic anhydride was employed as derivatizing agent in this study. After optimizing the SD-SFDF-LPME method, the limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.16 and 0.53 mg/kg, respectively. Quadruple isotope dilution (ID⁴) was coupled to the SD-SFDF-LPME method in order to alleviate matrix effects and promote accuracy/precision of the method. Chloroquine acetamide-d3 was firstly synthesized in our research laboratory and used as the isotopic analogue of the analyte in the ID⁴ experiments. Superior percent recovery results (99.4% - 101.0%) with low standard deviation values were obtained for the spiked samples. This validated the developed SD-SFDF-LPME-ID⁴-GC-MS method as highly accurate and precise for the determination of chloroquine phosphate at trace levels. In addition, the isotopic analogue of the analyte was obtained via the acetamide derivative of the analyte, which is an alternative to obtain isotopic analogues of organic compounds that are not accessible or commercially available.

The use of dried blood spots for characterizing children's exposure to organic environmental chemicals

Biomonitoring is a commonly used tool for exposure assessment of organic environmental chemicals with urine and blood samples being the most commonly used matrices. However, for children's studies, blood samples are often difficult to obtain. Dried blood spots (DBS) represent a potential matrix for blood collection in children that may be used for biomonitoring. DBS are typically collected at birth to screen for several congenital disorders and diseases; many of the states that are required to collect DBS archive these spots for years. If the archived DBS can be accessed by environmental health researchers, they potentially could be analyzed to retrospectively assess exposure in these children. Furthermore, DBS can be collected prospectively in the field from children ranging in age from newborn to school-aged with little concern from parents and minimal risk to the child. Here, we review studies that have evaluated the measurement of organic environmental toxicants in both archived and prospectively collected DBS, and where available, the validation procedures that have been performed to ensure these measurements are comparable to traditional biomonitoring measurements. Among studies thus far, the amount of validation has varied considerably with no studies systematically evaluating all parameters from field collection, shipping and storage contamination and stability to laboratory analysis feasibility. These validation studies are requisite to ensure reliability of the measurement and comparability to more traditional matrices. Thus, we offer some recommendations for validation studies and other considerations before DBS should be adopted as a routine matrix for biomonitoring.

A 'Dilute and Shoot' Liquid Chromatography-Mass Spectrometry Method for Multiclass Drug Analysis in Pre-Cut Dried Blood Spots

Drugs able to affect the auditory and nervous systems and consumed by workers to treatdifferent pathologies can represent a possible source of risk in the work environment. All the target compounds involved in the presented project show ototoxic and/or narcoleptic side effects and, for these reasons, occupational safety organizations have recognized them as potential causes of work injuries. A multiclass method for the analysis of 15 drugs among the most widespread worldwide (belonging to nine different classes including antihistamines, beta-blockers, antidepressants, Z-drugs and opioids), was developed and validated. This study describes a rapid, sensitive and effective method to analyse these substances in whole blood using tailored pre-cut dried blood spots. Detection was achieved with a triple quadrupole mass spectrometer after an easy and simple 'dilute and shoot' solubilisation followed by an UPLC separation. All the issues linked to the use of the dried blood spots and whole blood, such as haematocrit variability, volumetric evaluation and sample carrier choice were carefully studied and managed during method development. From the validation study results it emerged that this approach can be deemed successful thanks to its few pg µL-1 LOQs, good linear intervals, absolute recoveries of no less than 75%, an almost negligible matrix effect and accuracy and precision in line with the European and American guidelines for validation. All the obtained goals have been specifically pursued in order to encourage method diffusion as a primary prevention intervention, even in small private workplaces.

Development of an easy and rapid analytical method for the extraction and preconcentration of chloroquine phosphate from human biofluids prior to GC-MS analysis

A vortex assisted spraying based fine droplet formation liquid phase microextraction (VA-SFDF-LPME) method was developed to determine chloroquine phosphate at trace levels in human serum, urine and saliva samples by gas chromatography–mass spectrometry (GC–MS) with single quadrupole mass analyzer. In the first part, several liquid phase microextraction (LPME) and magnetic solid phase extraction (MSPE) methods were compared to each other in order to observe their extraction ability for the analyte. VA-SFDF-LPME method was selected as an efficient and easy extraction method due to its higher extraction efficiency. Optimization studies were carried out for the parameters such as extraction solvent type, sodium hydroxide volume/concentration, sample volume, spraying number and mixing type/period. Tukey's method based on post hoc test was applied to all experimental data for the selection of optimum values. Optimum extraction parameters were found to be 12 mL initial sample volume, two sprays of dichloromethane, 0.75 mL of 60 g/kg sodium hydroxide and 15 s vortex. Under the optimum conditions, limit of detection and quantification (LOD and LOQ) were calculated as 2.8 and 9.2 μg/kg, respectively. Detection power of the GC–MS system was increased by approximately 317 folds with the developed extraction/preconcentration method. The applicability and accuracy of the proposed method was evaluated by spiking experiments and percent recovery results for human urine, serum and saliva samples were found in the range of 90.9% and 114.0% with low standard deviation values (1.9–9.4).

Enantioselective in vitro ADME, absolute oral bioavailability, and pharmacokinetics of (-)-lumefantrine and (+)-lumefantrine in mice

Lumefantrine (LFN) is a chiral antimalarial drug. Enantioselective in vitro attributes and absolute oral pharmacokinetics for (-)-LFN and (+)-LFN have been characterized in mice. No stereoselectivity was seen with either of the enantiomers when compared with rac-LFN in the executed in vitro studies (solubility, metabolic stability, protein binding, permeability and blood partitioning). Post intravenous or oral administration of rac-LFN, the AUC_0-∞ and MRT of (+)-LFN was higher over (-)-LFN, which is reflected in higher clearance value for (-)-LFN. Following (-)-LFN intravenous administration to mice, the key PK parameters were comparable to (-)-LFN from rac-LFN; however, post intravenous administration of (+)-LFN alone to mice, the AUC_0-∞ was 1.3-fold higher than (+)-LFN from rac-LFN. Similarly, post oral administration of (-)-LFN to mice, both AUC_0-∞ and C_max were 1.3-fold higher than (-)-LFN from rac-LFN. On other hand, (+)-LFN showed 1.4-fold higher AUC_0-∞ and 1.7-fold higher C_max post oral administration over (+)-LFN from rac-LFN.

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.

A dried blood spot assay with HPLC-MS/MS for the determination of larotrectinib in mouse blood and its application to a pharmacokinetic study

Larotrectinib is a first-generation tropomyosin kinase inhibitor, approved for the treatment of solid tumors. In this paper, we present a validated dried blood spot (DBS) method for the quantitation of larotrectinib from mouse blood using HPLC-MS/MS, which was operated under multiple reaction monitoring mode. To the DBS disc cards, acidified methanol enriched with internal standard (IS; enasidenib) was added and extracted using tert-butyl methyl ether as an extraction solvent with sonication. Chromatographic separation of larotrectinib and the IS was achieved on an Atlantis dC₁₈ column using 10 mm ammonium formate-acetonitrile (30:70, v/v) delivered at a flow-rate of 0.80 ml/min. Under these optimized conditions, the retention times of larotrectinib and the IS were ~0.93 and 1.37 min, respectively. The total run time was 2.50 min. Larotrectinib and the IS were analyzed using positive ion scan mode and parent-daughter mass to charge ion (m/z) transitions of 429.1 → 342.1 and 474.1 → 267.1, respectively, were used for the quantitation. The calibration range was 1.06-5,080 ng/ml. No matrix effect or carryover was observed. Hematocrit did not influence DBS larotrectinib concentrations. All of the validation parameters met the acceptance criteria. The applicability of the validated method was shown in a mouse pharmacokinetic study.

Analytical Methods on Determination in Pharmaceuticals and Biological Materials of Chloroquine as Available for the Treatment of COVID-19

With the outbreak caused by the severe acute respiratory syndrome coronavirus (COVID-19), people's health and existing economies on a global scale are seriously threatened. Currently, most of the countries all over the world are studying extensively to better understand the antimalarial chloroquine (CQ) and hydroxychloroquine (HCQ) for therapeutic purposes due to the COVID-19 outbreak. However, CQ and HCQ can have serious side effects, from psychiatric effects to sudden death. Therefore, a faster and more effective detection method is needed to monitor drug concentrations. In this review, a large study was conducted on the detection techniques and quantitative determination methods of CQ and its related metabolites. In this review, chromatography, electrophoresis, electroanalytical, spectroscopic, and immunological methods for CQ and related metabolites are discussed extensively. It is hoped that a better understanding of the CQ used for therapeutic purposes in the COVID-19 outbreak will be provided.

Validated DBS method for filgotinib quantitation in rat dried blood spots and its application to a pharmacokinetic study in rats

Filgotinib is a selective JAK1 (Janus kinase) inhibitor, showed efficacy in patients suffering from moderate-to-severe rheumatoid arthritis. In this paper, we present the data on the development and validation of a sensitive, selective and high-throughput LC-MS/MS (liquid chromatography with tandem mass spectrometry) method for the quantitation of filgotinib from rat dried blood spot (DBS) cards. To the DBS disc cards, 0.2% formic acid enriched with internal standard (IS) was added and sonicated. Thereafter the extraction of filgotinib and the IS (tofacitinib) was accomplished using ethyl acetate as an extraction solvent. The resolution of filgotinib and the IS was achieved on a Gemini C₁₈ column with an isocratic mobile phase, which is a mixture of 0.2% formic acid:acetonitrile (20:80, v/v) at a flow-rate of 0.9 mL/min. The total run time was 2.90 min and the retention time of filgotinib and the IS was ~1.31 and 0.89 min, respectively. Filgotinib and the IS were analyzed using positive ion scan mode and parent-daughter mass to charge ion (m/z) transition of 426.3→291.3 and m/z 313.2→149.2, respectively, for quantitation. The calibration range was 1.37-1937 ng/mL. No matrix effect and carry over were observed. All the validation parameters met the acceptance criteria. The validated method has been applied to a pharmacokinetic study in rats. A good correlation between DBS and plasma concentrations for filgotinib was observed.

Multiplexed therapeutic drug monitoring of antipsychotics in dried plasma spots by LC-MS/MS

In this work, a convenient method for the therapeutic monitoring of seven common antipsychotic drugs in "dried plasma spot" samples has been developed. It is based on the liquid chromatography tandem mass spectrometry technique, operating in multiple reaction monitoring mode, and a straightforward procedure for the simultaneous extraction of all antipsychotics in a single step, with high extraction yield. The method was fully validated with proper accuracy, precision, selectivity and sensitivity, for all the drugs. Limits of quantification were 0.12, 1.09, 1.46, 1.47, 5.70, 1.32, 1.33 µg/L for haloperidol, aripiprazole, olanzapine, quetiapine, clozapine, risperidone, and paliperidone, respectively. Accuracy, intra- and interday precision values were <10% for all drugs at all concentration levels examined. The method was tested in the analysis of 30 plasma samples from real patients for each drug. The proposed analytical approach, by combining practical and logistical advantages of microsampling with liquid chromatography tandem mass spectrometry analytical performance, could offer an ideal strategy for accurate and timely therapeutic drug monitoring of antipsychotic drugs in most clinical settings, even in remote centers and/or in out-patient settings, bringing so many potential improvements in psychiatric patient care.

The Steps to Therapeutic Drug Monitoring: A Structured Approach Illustrated With Imatinib

Pharmacometric methods have hugely benefited from progress in analytical and computer sciences during the past decades, and play nowadays a central role in the clinical development of new medicinal drugs. It is time that these methods translate into patient care through therapeutic drug monitoring (TDM), due to become a mainstay of precision medicine no less than genomic approaches to control variability in drug response and improve the efficacy and safety of treatments. In this review, we make the case for structuring TDM development along five generic questions: 1) Is the concerned drug a candidate to TDM? 2) What is the normal range for the drug's concentration? 3) What is the therapeutic target for the drug's concentration? 4) How to adjust the dosage of the drug to drive concentrations close to target? 5) Does evidence support the usefulness of TDM for this drug? We exemplify this approach through an overview of our development of the TDM of imatinib, the very first targeted anticancer agent. We express our position that a similar story shall apply to other drugs in this class, as well as to a wide range of treatments critical for the control of various life-threatening conditions. Despite hurdles that still jeopardize progress in TDM, there is no doubt that upcoming technological advances will shape and foster many innovative therapeutic monitoring methods.

High sensitivity methods to quantify chloroquine and its metabolite in human blood samples using LC-MS/MS

Aim:

Chloroquine is an antimalarial drug used in the treatment of Plasmodium vivax malaria. Three methods to quantify chloroquine and its metabolite in blood matrices were developed and validated.

Methodology & results:

Different high-throughput extraction techniques were used to recover the drugs from whole blood (50 μl), plasma (100 μl) and dried blood spots (15 μl as punched discs) followed by quantification with LC–MS/MS. The intra- and inter-batch precisions were below 15%, and thus meet regulatory acceptance criteria.

Conclusion:

The developed methods demonstrated satisfactory validation performance with high sensitivity and selectivity. The assays used simple and easy to automate extraction techniques. All methods were reliable with robust performance and demonstrated to be suitable to implement into high-throughput routine analysis of clinical pharmacokinetic samples.

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.

Predictors of residual antimalarial drugs in the blood in community surveys in Tanzania

Background

Understanding pattern of antimalarials use at large scale helps ensuring appropriate use of treatments and preventing the spread of resistant parasites. We estimated the proportion of individuals in community surveys with residual antimalarials in their blood and identified the factors associated with the presence of the most commonly detected drugs, lumefantrine and/or desbutyl-lumefantrine (LF/DLF) or sulfadoxine-pyrimethamine (SP).

Methods

A cross-sectional survey was conducted in 2015 in three regions of Tanzania with different levels of malaria endemicity. Interviews were conducted and blood samples collected through household surveys for further antimalarial measurements using liquid chromatography coupled to tandem mass spectrometry. In addition, diagnosis and treatment availability was investigated through outlet surveys. Multilevel mixed effects logistic regression models were used to estimate odds ratios for having LF/DLF or SP in the blood.

Results

Amongst 6391 participants, 12.4% (792/6391) had LF/DLF and 8.0% (510/6391) SP in the blood. Factors associated with higher odds of detecting LF/DLF in the blood included fever in the previous two weeks (OR = 2.6, p<0.001), living in districts of higher malaria prevalence (OR = 1.5, p<0.001) and living in a ward in which all visited drug stores had artemisinin-based combination therapies in stocks (OR = 2.7, p = 0.020). Participants in older age groups were less likely to have LF/DLF in the blood (OR = 0.9, p<0.001). Factors associated with higher odds of having SP in the blood included being pregnant (OR = 4.6, p<0.001), living in Mwanza (OR = 3.9, p<0.001 compared to Mbeya), fever in the previous two weeks (OR = 1.7, p<0.001) and belonging to older age groups (OR = 1.2, p<0.001).

Conclusion

The most significant predictors identified were expected. History of fever in the past two weeks and young age were significant predictors of LF/DLF in the blood, which is encouraging. Antimalarial drug pressure was high and hence the use of recommended first-line drugs in combination with malaria Rapid Diagnostics Tests should be promoted to ensure appropriate treatment.

Novel organophosphorus aminopyrimidines as unique structural DNA-targeting membrane active inhibitors towards drug-resistant methicillin-resistant Staphylococcus aureus

A series of novel unique structural organophosphorus aminopyrimidines were developed as potential DNA-targeting membrane active inhibitors through an efficient one-pot procedure from aldehydes, phosphonate and aminopyrimidine. The biological assay revealed that some of the prepared compounds displayed antibacterial activities. In particular, imidazole derivative 2c exhibited more potent inhibitory activity against MRSA with an MIC value of 4 μg mL^-1 in comparison with the clinical drugs chloromycin and norfloxacin. Experiments revealed that the active molecule 2c had the ability to rapidly kill the tested strains without obviously triggering the development of bacterial resistance, showed low toxicity to L929 cells and could disturb the cell membrane. The molecular docking study discovered that compound 2c could bind with DNA gyrase via hydrogen bonds and other weak interactions. Further exploration disclosed that the active molecule 2c could also effectively intercalate into MRSA DNA and form a steady 2c-DNA supramolecular complex, which might further block DNA replication to exert powerful antibacterial effects.

Appropriateness of malaria diagnosis and treatment for fever episodes according to patient history and anti-malarial blood measurement: a cross-sectional survey from Tanzania

Background

Monitoring the impact of case management strategies at large scale is essential to evaluate the public health benefit they confer. The use of methodologies relying on objective and standardized endpoints, such as drug levels in the blood, should be encouraged. Population drug use, diagnosis and treatment appropriateness in case of fever according to patient history and anti-malarials blood concentration was evaluated.

Methods

A cross-sectional survey took place between May and August 2015 in three regions of Tanzania with different levels of malaria endemicity. Interviews were conducted and blood samples were collected by dried blood spots through household surveys for further anti-malarial measurements. Appropriate testing when individuals attended care was defined as a patient with history of fever being tested for malaria and appropriate treatment as (i) having anti-malarial in the blood if the test result was positive (ii) having anti-malarial in the blood if the person was not tested, and (iii) no anti-malarial in the blood when the test result was negative.

Results

Amongst 6391 participants included in the anti-malarial analysis, 20.8% (1330/6391) had anti-malarial drug detected in the blood. Only 28.0% (372/1330) of the individuals with anti-malarials in their blood reported the use of anti-malarials within the previous month. Amongst all participants, 16.0% (1021/6391) reported having had a fever in the previous 2 weeks and 37.5% of them (383/1021) had detectable levels of anti-malarials in the blood. Of the individuals who sought care in health facilities, 69.4% (172/248) were tested and 52.0% (129/248) appropriately treated. When other providers were sought, 6% (23/382) of the persons were appropriately tested and 44.2% (169/382) appropriately treated. Overall, the proportion of individuals treated was larger than that being tested [47.3% (298/630) treated, 31.0% (195/630) tested].

Conclusion

This study showed high prevalence of circulating anti-malarial drug in the sampled population. Efforts should be made to increase rapid diagnostic tests use at all levels of health care and improve compliance to test result in order to target febrile patients that are sick with malaria and reduce drug pressure. Objective drug measurements collected at community level represent a reliable tool to evaluate overall impact of case management strategies on population drug pressure.