Impact of repeated micro and macro blood sampling on clinical chemistry and haematology in rats for toxicokinetic studies

Non-clinical rodent safety studies are essential in the development of new medicines to assess for potential adverse effects. Typically, toxicokinetic samples are collected from a satellite group. AstraZeneca implemented repeated microsampling of main study animals as standard in the one-month small molecule regulatory toxicology studies. A retrospective analysis of the clinical chemistry and haematology data collected in 52 independent studies from the adult rat controls explored the impact of micro and macro sampling of main study animals. For the majority of variables, the blood sampling technique had no significant impact on the mean or range. For microsampling, a few variables had statistically significant effects on the mean signal but these were considered to have limited biological relevance and would therefore not introduce a meaningful bias to any toxicological evaluation. The macrosampling had the expected effects on the red cell parameters of haemoglobin, haematocrit and red blood count due to the larger blood volume draw. In contrast, microsampling showed no such changes. In conclusion, this large-scale retrospective analysis supports the use of microsampling, for toxicokinetics, of main study animals and enables us to conduct rodent toxicology studies without satellite animals and further reduce the number of animals used in toxicological assessments.

Microsampling to support pharmacokinetic clinical studies in pediatrics

BACKGROUND

Conventional sampling for pharmacokinetic clinical studies requires removal of large blood volumes from patients. This can result in a physiological/emotional burden for children. Microsampling to support pharmacokinetic clinical studies in pediatrics may reduce this burden.

METHODS

Parents/guardians and bedside nurses completed a questionnaire describing their perception of the use of microsampling compared to conventional sampling to collect blood samples, based on their child's participation or their own role within a paired-sample pharmacokinetic clinical study. Responses were based on a seven-point Likert scale and were analyzed using frequency distributions.

RESULTS

Fifty-one parents/guardians and seven bedside nurses completed a questionnaire. Parents/guardians (96%) and bedside nurses (100%) indicated that microsampling was highly acceptable and recommended as a method for collecting blood samples for pediatric patients. Responding to a question about the child indicating pain during the blood sampling procedure, 61% of parent/guardians reported no pain in their children, 14% remained neutral, and 26% reported that their child indicated pain; 71% of the bedside nurses slightly agreed that the children indicated pain.

CONCLUSIONS

This study strongly suggests that parents/guardians and bedside nurses prefer microsampling to conventional sampling to conduct pediatric pharmacokinetic clinical studies. Employing microsampling may support increased participation by children in these studies.

IMPACT

Pharmacokinetic clinical studies require the withdrawal of blood samples at multiple times during a dosing interval. This can result in a physiological or emotional burden, particularly for neonates or pediatric patients. Microsampling offers an important opportunity for pharmacokinetic clinical studies in vulnerable patient populations, where smaller sample volumes can be collected. However, microsampling is not commonly used in clinical studies. Understanding the perceptions of parents/guardians and bedside nurses about microsampling may ascertain if this technique offers an improvement to conventional blood sample collection to perform pharmacokinetic clinical studies for pediatric patients.

A Joint Technology Combining the Advantages of Capillary Microsampling with Mass Spectrometry Applied to the Trans-Resveratrol Pharmacokinetic Study in Mice

Mice are the most frequently used animals in pharmacokinetic studies; however, collecting series of blood samples from mice is difficult because of their small sizes and tiny vessels. In addition, due to the small sample size, it is problematic to perform high required quantification. Thus, present work aims to find an effective strategy for overcoming these challenges using trans-resveratrol as a tool drug. Based on the idea of a joint technology, the capillary microsampling (CMS) was chosen for blood sample collection from mice after delivery of trans-resveratrol (150 mg/kg) by gavage, and a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the determination of trans-resveratrol and its main metabolites. All the mouse blood samples were exactly collected by CMS without obvious deviation. This provided credible samples for subsequent quantitative analysis. The HPLC-MS/MS method was found to be sensitive, accurate, and repeatable, and the pharmacokinetic parameters for all analytes were comparable with those reported in previous studies. However, the present joint technology offers the advantages of less animal damage, easy for sample preparation, and improved reliability. It has overcome some of the major limitations revealed in previous pharmacokinetic studies in mice and therefore provides a more effective option for future studies.

Biomonitoring and Digital Data Technology as an Opportunity for Enhancing Animal Study Translation

The failure of animal studies to translate to effective clinical therapeutics has driven efforts to identify underlying cause and develop solutions that improve the reproducibility and translatability of preclinical research. Common issues revolve around study design, analysis, and reporting as well as standardization between preclinical and clinical endpoints. To address these needs, recent advancements in digital technology, including biomonitoring of digital biomarkers, development of software systems and database technologies, as well as application of artificial intelligence to preclinical datasets can be used to increase the translational relevance of preclinical animal research. In this review, we will describe how a number of innovative digital technologies are being applied to overcome recurring challenges in study design, execution, and data sharing as well as improving scientific outcome measures. Examples of how these technologies are applied to specific therapeutic areas are provided. Digital technologies can enhance the quality of preclinical research and encourage scientific collaboration, thus accelerating the development of novel therapeutics.

Capillary microsampling in clinical studies: opportunities and challenges in two case studies

Aim: Capillary microsampling of 15 μl whole blood from fingersticks or heelsticks was used to collect pharmacokinetic (PK) samples from pediatric subjects in two projects. Results: In a mebendazole multisite study in Ethiopia and Rwanda in subjects between 1 and 16 years old, complete PK profiles (7 timepoints) could be obtained, although some of the fingerstick samples were contaminated by the dosing formulation. In a multisite study with a respiratory syncytial virus drug in children between 1 and 24 months old, sparse PK sampling was done (2 samples). All samples were successfully analyzed even though some capillaries were not properly filled. Conclusion: CMS shows potential for PK sampling in pediatrics but may need further optimization.

Application of tail vein serial microsampling for plasma or dried plasma spots in toxicokinetic assessment in rats using acetaminophen as the model compound

In the current study, two groups of rats (five per group) were administered a single oral dose of 500 mg/kg acetaminophen. For toxicokinetic assessment, the Group 1 animals were bled via conventional sparse (two animals/time point) sublingual vein bleeding (~0.5 ml) with anesthesia, while the Group 2 animals were bled via serial tail vein microsampling (~0.075 ml) without anesthesia. All collected blood was processed for plasma. Each Group 2 plasma sample (~30 μl) was divided into 'wet' and 'dried' (dried plasma spots). All plasma samples were analyzed by LC-MS/MS for acetaminophen and its major metabolites acetaminophen glucuronide and acetaminophen sulfate. In addition, plasma and urine samples were collected for analysis of corticosterone and creatinine to assess stress levels. Comparable plasma exposure to acetaminophen and its two metabolites was observed in the plasma obtained via conventional sparse sublingual vein bleeding and serial tail vein microsampling and between the 'wet' and 'dried' plasma obtained by the latter. Furthermore, comparable corticosterone levels or corticosterone/creatinine ratios between the two groups suggested that serial microsampling without anesthesia did not increase the levels of stress as compared with conventional sampling with anesthesia, confirming the utility of microsampling for plasma or dried plasma spots in rodent toxicokinetic assessment.

Capillary microsampling in mice: effective way to move from sparse sampling to serial sampling in pharmacokinetics profiling

Pharmacokinetic studies are an integral part of drug discovery and development. Mice are the commonly used species for pharmacokinetics studies during early discovery studies. Conventionally, composite PK profiles are obtained from mice studies due to the physiological limitations of the total blood volume that can be drawn over a certain period.With advancements in bioanalytical instrumentation and in blood sampling techniques, analysis with small volume (<50 µL) became feasible enabling serial blood sampling from the mouse for PK studies. The objective of the current study was to develop and establish a serial blood sampling technique in mouse and compare it with the conventional sparse sampling method (composite PK) following oral administration of widely used NSAIDs, diclofenac, celecoxib and tenoxicam, into Swiss Albino mice.The pharmacokinetic parameters of all three probe drugs by serial blood sampling were comparable with that of sparse sampling method. There was no significant difference between the whole blood concentration time profiles of all three drugs between serial sampling and sparse sampling suggesting serial blood sampling method can be easily implemented for mice PK studies.Serial blood sampling technique requires use of fewer number of animals, less quantity of test compound and reduces the possible dosing errors as fewer number of animals need to be dosed resulting in quality PK data and enabling comparison of inter-animal differences in PK profile.

Comparison of toxicokinetic parameters of a drug and two metabolites following traditional and capillary microsampling in rat

Aim: Following the request of a regulatory authority, a rat study was conducted to compare pharmacokinetic parameters from traditional large volume sampling and capillary microsampling. Materials & methods: Rats were dosed with a proprietary compound in three dose groups and blood samples were collected via capillary microsampling (32 μl), immediately followed by traditional large volume sampling (300 μl) up to 24 h postdose. Resulting plasma samples were analyzed for parent drug and two metabolites. AUCs were compared between sampling techniques. Results: There was no statistical difference between AUCs from traditional and microsampling across different doses and analytes. Conclusion: Toxicokinetic parameters generated from plasma collected as a capillary microsample or traditional large volume sample are highly comparable.

Analysis of capillary microsamples obtained from a skin-prick to measure vancomycin concentrations as a valid alternative to conventional sampling: A bridging study

A bridging study is presented to investigate the applicability of measuring vancomycin concentrations obtained by finger-prick. A total of 25 paired plasma samples, collected from finger prick as capillary microsampling and arterial plasma samples collected from an indwelling cannula as conventional sampling, were obtained from critically ill patients receiving vancomycin. The maximum concentration (C_max) and the minimum concentration (C_min) measured were 66.2 mg/L and 29.7 mg/L for capillary microsampling and 78.9 mg/L, 25.6 mg/L for conventional sampling, respectively. The area under the concentration-time curve from 0 to 6 h (AUC_0-6h) ranged between 94.8 and 269 mg/L.h for capillary microsampling and from 106 and 303 mg/L.h for conventional sampling. The comparative study conducted was assessed using three different statistical approaches: Bland-Altman and Passing-Bablok regression analyses and the USFDA criterion for the incurred sample reanalysis. The results of this analysis revealed no significant bias and a strong correlation between both sampling methods, with 95% of the calculated concentrations from the paired plasma samples laying within 20% of difference of the mean. This bridging study verifies that capillary microsampling may serve as an alternative to conventional sampling techniques to support clinical applications for measuring vancomycin concentrations in plasma.

Feedback from the European Bioanalysis Forum liquid microsampling consortium: microsampling: assessing accuracy and precision of handheld pipettes and capillaries

Aim: Microsampling in preclinical pharmacokinetics (PK) studies is currently widely adopted across the pharmaceutical industry. Materials & methods: The European Bioanalysis Forum liquid microsampling consortium member companies assessed the accuracy and precision of handheld pipettes and microcapillaries at volumes of less than 10 μl. The following key factors on pipetting performance were also evaluated: Pipette type (positive displacement, air displacement and microcapillary), experience of user and the liquid type. Water was selected as a best-case scenario for accuracy and precision determination and blood plasma as a ‘real world’ bioanalysis sample type. Conclusion: Accuracy and precision on the pipetted volume decreased at lower volumes and experienced laboratory technicians performed better compared with the infrequent users. With respect to the pipetting devices used, microcapillaries showed better or equivalent accuracy and precision compared with handheld pipettes across the volume range 1–8 μl independent of the matrix used.

A practical workflow for capillary microsampling in nonclinical studies

Aim: The result of investigation on the procedure of sample handling and bioanalysis of small volume of plasma sample for nonclinical studies stored in 0.5-ml micronic tubes was reported. Results/methodology: Sample integrity of the small volume (25 μl) during long-term storage and the feasibility and data reliability of performing multiple re-assays on the small volume sample using 5 μl aliquot per analysis was evaluated. Conclusion: Integrity was maintained in samples (25 μl) stored for up to 1 month in 0.5-ml micronic tubes at -20°C. A 25 μl sample is sufficient for four-times of re-assays. This evaluation demonstrated the feasibility of this workflow of handling and bioanalysis on small volume plasma sample for GLP studies under the US FDA guidance.

Clinical application of microsampling versus conventional sampling techniques in the quantitative bioanalysis of antibiotics: a systematic review

Conventional sampling techniques for clinical pharmacokinetic studies often require the removal of large blood volumes from patients. This can result in a physiological or emotional burden, particularly for neonates or pediatric patients. Antibiotic pharmacokinetic studies are typically performed on healthy adults or general ward patients. These may not account for alterations to a patient’s pathophysiology and can lead to suboptimal treatment. Microsampling offers an important opportunity for clinical pharmacokinetic studies in vulnerable patient populations, where smaller sample volumes can be collected. This systematic review provides a description of currently available microsampling techniques and an overview of studies reporting the quantitation and validation of antibiotics using microsampling. A comparison of microsampling to conventional sampling in clinical studies is included.

Incorporating dried blood spot LC–MS/MS analysis for clinical development of a novel oncolytic agent

Aim: Design and execution of a dried blood spot (DBS-LC–MS/MS) assay for pharmacokinetic analyses in oncology patients. Results & discussion: The methodology was validated to collect and store DBS samples from multiple clinical sites, and analyze blood with diverse hematocrit ranges (25–55) to match the potential patient population. Bridging data comparing DBS and plasma showed high degree of concordance with DBS:plasma ratios of 0.81, demonstrating no preferential uptake or association with cellular components of the blood. Pharmacokinetic analysis supporting clinical development was performed using 20 μl of blood collected as DBS. Incurred sample reanalysis showed high correlation. Conclusion: Successful validation of a DBS method and implementation in the clinic enabled pharmacokinetic analysis during the clinical development of a novel oncolytic agent in oncology patients.

Volumetric absorptive microsampling combined with impact-assisted extraction for hematocrit effect free assays

Aim: Volumetric absorptive microsampling (VAMS) is a recent technology available for sampling and analyzing low blood volume. The present work describes the utilization of VAMS for the quantitation of naproxen and ritonavir in human blood using a novel bead-based impact-assisted extraction (IAE) procedure. Results: Sampling volume accuracy of the VAMS device was independent of the blood hematocrit (HCT) level, however analyte recovery decreased with increasing HCT when extracted using ultrasonication. In contrast, IAE was unaffected by HCT, resulting in quantitative recovery for all levels evaluated. Precision and accuracy batches, as well as matrix effect evaluation, met acceptance criteria. Conclusion: The IAE procedure coupled with VAMS is immune to HCT biases affecting sampling volume and recovery.

Outsourcing bioanalytical services at Janssen Research and Development: the sequel anno 2017

The strategy of outsourcing bioanalytical services at Janssen has been evolving over the last years and an update will be given on the recent changes in our processes. In 2016, all internal GLP-related activities were phased out and this decision lead to the re-orientation of the in-house bioanalytical activities. As a consequence, in-depth experience with the validated bioanalytical assays for new drug candidates is currently gained together with the external partner, since development and validation of the assay and execution of GLP preclinical studies are now transferred to the CRO. The evolution to externalize more bioanalytical support has created opportunities to build even stronger partnerships with the CROs and to refocus internal resources. Case studies are presented illustrating challenges encountered during method development and validation at preferred partners when limited internal experience is obtained or with introduction of new technology.

Capillary microsampling in nonclinical safety assessment: practical sampling and bioanalysis from a CRO perspective

Microsampling has the 3R benefits of refining blood collection techniques while reducing the number of animals required for rodent safety assessment studies. There are significant scientific benefits of correlating study findings with systemic exposure and consequently, there is an industry drive to utilize microsampling in regulatory toxicology studies. This article will focus on capillary microsampling and will discuss the initial considerations before using capillary microsampling, study design and some practicalities of sample collection. From a bioanalytical perspective, the impact of different sample collection and storage workflows on the design of method validation experiments, the suitability of using microsampling for unstable analytes and aspects supporting analysis of peptides, large molecules and for biomarker applications will be discussed.

The application of capillary microsampling in GLP toxicology studies

Aim: Capillary microsampling (CMS) to collect microplasma volumes is gradually replacing traditional, larger volume sampling from rats in GLP toxicology studies. Methodology: About 32 µl of blood is collected with a capillary, processed to plasma and stored in a 10- or 4-µl capillary which is washed out further downstream in the laboratory. CMS has been standardized with respect to materials, assay validation experiments and application for sample analysis. Conclusion: The implementation of CMS has resulted in blood volume reductions in the rat from 300 to 32 µl per time point and the elimination of toxicokinetic satellite groups in the majority of the rat GLP toxicology studies. The technique has been successfully applied in 26 GLP studies for 12 different projects thus far.

Effects of Capillary Microsampling on Toxicological Endpoints in Juvenile Rats

Blood sampling during juvenile rat toxicology studies is required to determine the toxicokinetic (TK) profile of compounds. Juvenile rats are too small to undergo repeated blood sampling using conventional methods, which collect 200-300 μl blood at each time point. Recently, capillary microsampling (CMS) gained interest because sample sizes are almost 10 times smaller enabling multi-sample collection from 1 rat. Here, we evaluated the use of CMS in juvenile rats in support of reduced animal usage. Juvenile rats at postnatal day (PND) 4, 10, and 17 underwent CMS via the submandibular, tail, and jugular veins. The CMS methods for pups at different ages were evaluated based on sample quality and technical practicality as well as on acute and chronic changes of toxicological parameters. The best location for CMS was the submandibular vein for PND 4 and 10 pups and the tail vein for PND 17 pups. No effects were found on clinical signs, body and organ weights and biochemistry parameters when 2 × 32 μl of blood was withdrawn from PND 4 pups or when 3 × 32 μl was taken from PND 10 and 17 pups within 24 h. Significant changes in several hematology parameters were observed 24 h after CMS due to a decrease of red blood cells and renewed production. These values had recovered to normal 7 days after CMS. CMS is feasible in juvenile rats for TK assessment. Utilizing this method could decrease the number of additional animals by 75%.

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.

Evaluation of two blood microsampling approaches for drug discovery PK studies in rats

Background: Serial sampling in discovery rat PK studies could be performed via capillary microsampling (CMS) of blood or by using the Mitra™ device to collect dried blood samples. Results: Blood CMS results were compared with Mitra sampling results for four test compounds dosed in rat PK studies. The PK profiles obtained from CMS sampling were found to be very similar to those obtained from the Mitra sampling. For 15-µl blood CMS samples, freezing before the dilution step was found to be acceptable. Conclusion: Blood CMS using 15-µl glass capillary microsamples works well for serial blood sampling in rat PK studies. The Mitra microsampling device provides an alternative method for collecting 10 µl of blood as a dried blood sample.

Utility of capillary microsampling for rat pharmacokinetic studies: Comparison of tail-vein bleed to jugular vein cannula sampling

INTRODUCTION

Serial sampling methods have been used for rat pharmacokinetic (PK) studies for over 20 years. Currently, it is still common to take 200-250 μL of blood at each timepoint when performing a PK study in rats and using serial sampling. While several techniques have been employed for collecting blood samples from rats, there is only limited published data to compare these methods. Recently, microsampling (≤ 50 μL) techniques have been reported as an alternative process for collecting blood samples from rats.

METHODS

In this report, five compounds were dosed orally into rats. For three proprietary compounds, jugular vein cannula (JVC) sampling was used to collect whole blood and plasma samples and capillary microsampling (CMS) was used to collect blood samples from the tail vein of the same animal. For the two other compounds, marketed drugs fluoxetine and glipizide, JVC sampling was used to collect both whole blood and blood CMS samples while tail-vein sampling from the same rats was also used to collect both whole blood and blood CMS samples.

RESULTS

For the three proprietary compounds, the blood AUC as well as the blood concentration-time profile that were obtained from the tail vein were different from those obtained via JVC sampling. For fluoxetine, the blood total exposure (AUC) was not statistically different when comparing tail-vein sampling to JVC sampling, however the blood concentration-time profile that was obtained from the tail vein was different than the one obtained from JVC sampling. For glipizide, the blood AUC and concentration-time profile were not statistically different when comparing the tail-vein sampling to the JVC sampling. For both fluoxetine and glipizide, the blood concentration profiles obtained from CMS were equivalent to the blood concentration profiles obtained from the standard whole blood sampling, collected at the same sampling site.

DISCUSSION

The data in this report provide strong evidence that blood CMS is a valuable small volume blood sampling approach for rats and that it provides results for test compound concentrations that are equivalent to those obtained from traditional whole blood sampling. The data also suggest that for some compounds, the concentration-time profile that is obtained for a test compound based on sampling from a rat tail vein may be different from that obtained from rat JVC sampling. In some cases, this shift in the concentration-time profile will result in different PK parameters for the test compound. Based on these observations, it is recommended that a consistent blood sampling method should be used for serial microsampling in discovery rat PK studies when testing multiple new chemical entities. If the rat tail vein sampling method is selected for PK screening, then conducting a bridging study on the lead compound is recommended to confirm that the rat PK obtained from JVC sampling is comparable to the tail-vein sampling.

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.

Capillary microsampling of whole blood for mouse PK studies: an easy route to serial blood sampling

Background: Capillary microsampling (CMS) of 8 µl of blood provides a methodology that can be utilized for serial sampling in drug discovery mouse PK studies. Results: Blood CMS sample results were compared to plasma sample results for three compounds (with expected Cb/Cp of 1 to 2) and found to be similar. In addition, for three compounds, blood CMS results were found to be equivalent to results generated with standard whole blood sampling. In a 5-day repeated dose PK study, four mice were dosed (IV) daily and sampled on both day one and day five using blood CMS procedure. Conclusion: Blood CMS using 8 µl glass capillary microsamples provides a straightforward and effective approach for mouse serial blood sampling.