Dried Urine Spot Analysis for assessing cardiovascular drugs exposure applicable in spaceflight conditions

Cardiovascular pharmacological countermeasures will be required as a preventive measure of cardiovascular deconditioning and early vascular ageing for long term space travelers. Physiological changes during spaceflight could have severe implications on drug pharmacokinetics and pharmacodynamics (PK/PD). However, limitations exist for the implementation of drug studies due to the requirements and constraints of this extreme environment. Therefore, we developed an easy sampling method on dried urine spot (DUS), for the simultaneous quantification of 5 antihypertensive drugs in human urine: irbesartan, valsartan, olmesartan, metoprolol and furosemide analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), considering spaceflight parameters. This assay was validated in terms of linearity, accuracy, and precision with satisfactory results. There were no relevant carry-over, matrix interferences. The targeted drugs were stable in urine collected by DUS until 6 months at +21 °C, +4°C, -20 °C (with or without desiccants) and at 30 °C during 48 h. Irbesartan, valsartan and olmesartan were not stable at 50 °C during 48 h. This method was found to be eligible for space pharmacology studies in terms of practicality, safety, robustness and energy costs. It has been successfully implemented in space tests programs led in 2022.

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

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.

Official International Association for Therapeutic Drug Monitoring and Clinical Toxicology Guideline: Development and Validation of Dried Blood Spot-Based Methods for Therapeutic Drug Monitoring

Dried blood spot (DBS) analysis has been introduced more and more into clinical practice to facilitate Therapeutic Drug Monitoring (TDM). To assure the quality of bioanalytical methods, the design, development and validation needs to fit the intended use. Current validation requirements, described in guidelines for traditional matrices (blood, plasma, serum), do not cover all necessary aspects of method development, analytical- and clinical validation of DBS assays for TDM. Therefore, this guideline provides parameters required for the validation of quantitative determination of small molecule drugs in DBS using chromatographic methods, and to provide advice on how these can be assessed. In addition, guidance is given on the application of validated methods in a routine context. First, considerations for the method development stage are described covering sample collection procedure, type of filter paper and punch size, sample volume, drying and storage, internal standard incorporation, type of blood used, sample preparation and prevalidation. Second, common parameters regarding analytical validation are described in context of DBS analysis with the addition of DBS-specific parameters, such as volume-, volcano- and hematocrit effects. Third, clinical validation studies are described, including number of clinical samples and patients, comparison of DBS with venous blood, statistical methods and interpretation, spot quality, sampling procedure, duplicates, outliers, automated analysis methods and quality control programs. Lastly, cross-validation is discussed, covering changes made to existing sampling- and analysis methods. This guideline of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology on the development, validation and evaluation of DBS-based methods for the purpose of TDM aims to contribute to high-quality micro sampling methods used in clinical practice.

Quantitation of Fentanyl Analogs in Dried Blood Spots by Flow-Through Desorption Coupled to Online Solid Phase Extraction Tandem Mass Spectrometry

An automated dried blood spot (DBS) elution coupled with solid phase extraction and tandem mass spectrometric analysis for multiple fentanyl analogs was developed and assessed. This method confirms human exposures to fentanyl, sufentanil, carfentanil, alfentanil, lofentanil, α-methyl fentanyl, and 3-methyl fentanyl in blood with minimal sample volume and reduced shipping and storage costs. Seven fentanyl analogs were detected and quantitated from DBS made from venous blood. The calibration curve in matrix was linear in the concentration range of 1.0 ng/mL to 100 ng/mL with a correlation coefficient greater than 0.98 for all compounds. The limit of detection varied from 0.15 ng/mL to 0.66 ng/mL depending on target analyte. Analysis of the entire DBS minimized the effects of hematocrit on quantitation. All quality control materials evaluated resulted in <15% error; analytes with isotopically labeled internal standards had <15% RSD, while analytes without matching standards had 15-24% RSD. This method provides an automated means to detect seven fentanyl analogs, and quantitate four fentanyl analogs with the benefits of DBS at levels anticipated from an overdose of these potent opioids.

HRMS using a Q-Exactive series mass spectrometer for regulated quantitative bioanalysis: how, when, and why to implement

High-resolution MS (HRMS) has seen an uptake in use for discovery qual/quan workflows, however, its utilization in late discovery/development has been slow. Past reports comparing HRMS to triple quadrupole (QQQ) instrumentation to date have indicated that HRMS instruments are capable of producing data acceptable for regulated bioanalysis, however lack the sensitivity required for sub ng/ml LLOQ assays. Recent advances in HRMS instrumentation have closed the sensitivity gap with QQQ and have even provided improved selectivity and sensitivity over QQQ SRM assays. Herein, the authors will describe how, when, and why HRMS (specifically Q-Exactive series mass spectrometers) should be considered for implementation in regulated quantitative bioanalysis assays.

Discovery bioanalysis and in vivo pharmacology as an integrated process: a case study in oncology drug discovery

Background: A bioanalytical team dedicated to in vivo pharmacology was set up to accelerate the selection and characterization of compounds to be evaluated in animal models in oncology. Results: A DBS-based serial microsampling procedure was optimized from sample collection to extraction to obtain a generic procedure. UHPLC–high-resolution mass spectrometer configuration allowed for fast quantitative and qualitative analysis. Using an optimized lead compound, we show how bioanalysis supported in vivo pharmacology by generating blood and tumor exposure, drug monitoring and PK/PD data. Conclusion: This process provided unique opportunities for the characterization of drug properties, selection and assessment of compounds in animal models and to support and expedite proof-of-concept studies in oncology.

Novel membrane devices and their potential utility in blood sample collection prior to analysis of dried plasma spots

Background: Construction and application of a novel membrane substrate dried plasma spot (DPS) card is described. Results/methodology: The online automation compatible prototype DPS card employs a membrane filter to remove red blood cells from whole blood for the collection of plasma. The described autoDPS card provides acceptable quantitative precision and accuracy data from plasma filtered from 45% hematocrit whole blood. When significantly lower or higher hematocrit (30 and 60%) whole blood fortified with guanfacine is applied, the quantitative precision and accuracy data fall outside regulated 15/20 bioanalytical acceptance criteria. Conclusion: The described prototype DPS card works well for normal hematocrit whole blood, but further development is needed for samples of much lower or higher hematocrit.

DBS direct elution: optimizing performance in high-throughput quantitative LC–MS/MS analysis

Background: Automated DBS direct elution techniques eliminate the manual extraction burden of DBS bioanalysis, offer good quantitative performance, the ability to eliminate hematocrit-based assay bias, and, previous reports have demonstrated that significant increases in assay sensitivity compared with manual DBS extraction are possible. Results: An investigation into elucidating parameters for optimized generic DBS direct elution for high sample throughput quantitative bioanalytical applications is presented for the first time. Generic direct elution conditions were identified that enabled LC–MS/MS assay sensitivity to be maximized while retaining acceptable chromatographic performance. Conclusion: Compared with generic conventional DBS manual extraction, assay sensitivity was demonstrated to be increased up to 33-fold across four representative small molecule compounds, using the recommended direct elution conditions.

Hematocrit-independent recovery of immunosuppressants from DBS using heated flow-through desorption

Background: We applied our concept for automated flow-through desorption of DBS to investigate the effect of desorption temperature on recovery. For this purpose, a method has been developed for the determination of four immunosuppressants in DBS. Results: We compared recoveries of four immunosuppressants for measurements with and without temperature-enhanced desorption at different hematocrit (Ht) levels. Temperature-enhanced desorption increased recovery substantially for tacrolimus, sirolimus and everolimus at all Ht values and for cyclosporine At high Ht. In addition, recovery became largely independent from Ht variations. Under the optimized conditions, a brief validation using spiked blood samples showed that the method complies with acceptance criteria for quantitative bioanalysis. Conclusion: This method enables a quantitative analysis of immunosuppressants in DBS independent from the Ht.

Dried blood spot analysis for rat and dog studies: validation, hematocrit, toxicokinetics and incurred sample reanalysis

Background: Execution of experiments to introduce dried blood spot (DBS) sampling for preclinical GLP studies and subsequent clinical studies. Results: Bridging data showed high concordance with DBS:plasma ratios of 0.9 in rats and 1.1 in dogs, demonstrating no preferential uptake or association with cellular components of the blood. The DBS methodology was fully validated incorporating additional experiments pertinent to DBS sampling, storage and analysis. Individual hematocrit (Hct) values in the test animals (rats and dogs) were within the validated Hct range. DBS concentration data and the resulting TK profiles were not impacted by an Hct bias. Incurred sample reanalysis showed high correlation in dogs (97%) and rats (100%) meeting acceptance criteria. Conclusion: Successfully validated and adopted DBS for preclinical GLP studies.

Automated high-capacity on-line extraction and bioanalysis of dried blood spot samples using liquid chromatography/high-resolution accurate mass spectrometry

RATIONALE

Pharmacokinetic data to support clinical development of pharmaceuticals are routinely obtained from liquid plasma samples. The plasma samples require frozen shipment and storage and are extracted off-line from the liquid chromatography/tandem mass spectrometry (LC/MS/MS) systems. In contrast, the use of dried blood spot (DBS) sampling is an attractive alternative in part due to its benefits in microsampling as well as simpler sample storage and transport. However, from a practical aspect, sample extraction from DBS cards can be challenging as currently performed. The goal of this report was to integrate automated serial extraction of large numbers of DBS cards with on-line liquid chromatography/high-resolution accurate mass spectrometry (LC/HRAMS) bioanalysis.

METHODS

An automated system for direct DBS extraction coupled to a LC/HRAMS was employed for the quantification of midazolam (MDZ) and α-hydroxymidazolam (α-OHMDZ) in human blood. The target analytes were directly extracted from the DBS cards onto an on-line chromatographic guard column followed by HRAMS detection. No additional sample treatment was required. The automated DBS LC/HRAMS method was developed and validated, based on the measurement at the accurate mass-to-charge ratio of the target analytes to ensure specificity for the assay.

RESULTS

The automated DBS LC/HRAMS method analyzed a DBS sample within 2 min without the need for punching or additional off-line sample treatment. The fully automated analytical method was shown to be sensitive and selective over the concentration range of 5 to 2000 ng/mL. Intra- and inter-day precision and accuracy was less than 15% (less than 20% at the LLOQ). The validated method was successfully applied to measure MDZ and α-OHMDZ in an incurred human sample after a single 7.5 mg dose of MDZ.

CONCLUSIONS

The direct DBS LC/HRAMS method demonstrated successful implementation of automated DBS extraction and bioanalysis for MDZ and α-OHMDZ. This approach has the potential to promote workload reduction and sample throughput increase.