Development and validation of a dried blood spot-LC-APCI-MS assay for estimation of canrenone in paediatric samples

Clinical Validation of a Dried Blood Spot Assay for 8 Antihypertensive Drugs and 4 Active Metabolites

BACKGROUND

Drug nonadherence is one of the major challenges faced by resistant hypertension patients, and identification of this problem is needed for optimizing pharmacotherapy. Dried blood spot (DBS) sampling is a minimally invasive method designed to detect and determine the degree of nonadherence. In this study, a DBS method for qualifying 8 antihypertensive drugs (AHDs) and 4 active metabolites was developed and validated using ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS).

METHOD

The DBS assay was validated analytically and clinically, in accordance with FDA requirements. Analytical validation was accomplished using UHPLC-MS/MS. For clinical validation, paired peak and trough levels of DBS and plasma samples were simultaneously collected and comparatively analyzed using Deming regression and Bland-Altman analyses. All concentrations below the set lower limit were excluded. Deming regression analysis was used to predict comparison bias between the collected plasma and DBS samples, with DBS concentrations corrected accordingly.

RESULTS

The UHPLC-MS/MS method for simultaneously measuring 8 AHDs and their metabolites in DBS, was successfully validated. With Deming regression no bias was observed in N = 1; constant bias was seen in N = 6 and proportional bias in N = 11 of the AHDs and metabolites. After correction for bias, only one metabolite (canrenone) met the 20% acceptance limit for quantification, after Bland-Altman analyses. In addition, amlodipine, valsartan, and [enalaprilate] met the 25% acceptance limit.

CONCLUSIONS

A novel DBS assay for simultaneously qualifying and quantifying 8 AHDs and their metabolites, has been successfully developed and validated. The DBS assay is therefore a suitable method to detect drug nonadherence. However, with the exception of canrenone, the interchangeable use of plasma and DBS sampling to interpret drug quantities should be avoided.

Technological advancement in dry blood matrix microsampling and its clinical relevance in quantitative drug analysis

In the past few decades, dried blood matrix biosampling has witnessed a marvelous interest among the researcher due to its user-friendly operation during blood sampling in preclinical and clinical applications. It also complies with the basic 3Rs (reduce, reuse and recycle) philosophy. Because of comparative simplicity, a huge number of researchers are paying attention to its technological advancements for widespread application in the bioanalysis and diagnosis arena. In this review, we have explained different approaches to be considered during dried blood matrix based microsampling including their clinical relevance in therapeutic drug monitoring. We have also discussed various strategies for avoiding and minimizing major unwanted analytical interferences associated with this technique during drug quantification. Further, various recent technological advancement in microsampling devices has been discussed correlating their clinical applications.

Emerging trends in paper spray mass spectrometry: Microsampling, storage, direct analysis, and applications

Recent advancements in the sensitivity of chemical instrumentation have led to increased interest in the use of microsamples for translational and biomedical research. Paper substrates are by far the most widely used media for biofluid collection, and mass spectrometry is the preferred method of analysis of the resultant dried blood spot (DBS) samples. Although there have been a variety of review papers published on DBS, there has been no attempt to unify the century old DBS methodology with modern applications utilizing modified paper and paper-based microfluidics for sampling, storage, processing, and analysis. This critical review will discuss how mass spectrometry has expanded the utility of paper substrates from sample collection and storage, to direct complex mixture analysis to on-surface reaction monitoring.

Development and validation of a fast and sensitive UHPLC-ESI-MS method for the simultaneous quantification of spironolactone and its metabolites in ocular tissues

Glucocorticoids are a mainstay for the treatment of immune-mediated conditions and inflammatory diseases. However, their chronic use causes numerous side-effects including delays in corneal and cutaneous wound healing. This is attributed to off-target agonism of the mineralocorticoid receptor, which can be reduced by co-administration of a mineralocorticoid receptor antagonist such as spironolactone. The aim of this study was to develop a fast, selective and sensitive UHPLC-ESI-MS method for the simultaneous quantification of spironolactone, its active metabolites (7α-thiomethylspironolactone and canrenone), the latter's water-soluble prodrug potassium canrenoate and the synthetic glucocorticoid, dexamethasone, in corneal samples (17α-methyltestosterone served as an internal standard). A one-step extraction procedure using MeOH-H₂ O (1:1) was validated and employed to recover the analytes from the corneal tissue. Extracts were centrifuged and the supernatant analyzed under isocratic conditions. Compounds were detected using selected ion recording mode. The method satisfied US Food and Drug Administration guidelines with respect to selectivity, precision and accuracy and displayed linearity from 5 to 1000 ng/mL for all of the analytes. The lower limit of quantitation of the method was 5 ng/mL, making it sufficiently sensitive for quantification of the analytes in samples from in vivo studies.

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.

Quantitative analysis of methyl and propyl parabens in neonatal DBS using LC–MS/MS

Aim: Excipients are used to overcome the chemical, physical and microbiological challenges posed by developing formulated medicines. Both methyl and propyl paraben are commonly used in pediatric liquid formulations. There is no data on systemic exposure to parabens in neonates. The European Study of Neonatal Exposure to Excipients project has investigated this. Results & methodology: DBS sampling was used to collect opportunistic blood samples. Parabens were extracted from the DBS and analyzed using a validated LC–MS/MS assay. Discussion & conclusion: The above assay was applied to analyze neonatal DBS samples. The blood concentrations of parabens in neonates confirm systemic exposure to parabens following administration of routine medicines.

Dried blood spots analysis with mass spectrometry: Potentials and pitfalls in therapeutic drug monitoring

Therapeutic drug monitoring (TDM) relays in the availability of specialized laboratory assays, usually available in reference centers that are not accessible to all patients. In this context, there is a growing interest in the use of dried blood spot (DBS) sampling, usually obtained from finger pricks, which allows simple and cost-effective logistics in many settings, particularly in Developing Countries. The use of DBS assays to estimate plasma concentrations is highly dependent on the hematocrit of the blood, as well as the particular characteristics of the measured analyte. DBS assays require specific validation assays, most of them are related to hematocrit effects. In the present manuscript, the application of mass spectrometric assays for determination of drugs for TDM purposes in the last ten years is reviewed, as well as the particular validation assays for new DBS methods.

Observational infant exploratory [(14)C]-paracetamol pharmacokinetic microdose/therapeutic dose study with accelerator mass spectrometry bioanalysis

AIMS

The aims of the study were to compare [(14)C]-paracetamol ([(14)C]-PARA) paediatric pharmacokinetics (PK) after administration mixed in a therapeutic dose or an isolated microdose and to develop further and validate accelerator mass spectrometry (AMS) bioanalysis in the 0-2 year old age group.

METHODS

[(14)C]-PARA concentrations in 10-15 µl plasma samples were measured after enteral or i.v. administration of a single [(14)C]-PARA microdose or mixed in with therapeutic dose in infants receiving PARA as part of their therapeutic regimen.

RESULTS

Thirty-four infants were included in the PARA PK analysis for this study: oral microdose (n = 4), i.v. microdose (n = 6), oral therapeutic (n = 6) and i.v. therapeutic (n = 18). The respective mean clearance (CL) values (SDs in parentheses) for these dosed groups were 1.46 (1.00) l h(-1), 1.76 (1.07) l h(-1), 2.93 (2.08) l h(-1) and 2.72 (3.10) l h(-1), t(1/2) values 2.65 h, 2.55 h, 8.36 h and 7.16 h and dose normalized AUC(0-t) (mg l(-1) h) values were 0.90 (0.43), 0.84 (0.57), 0.7 (0.79) and 0.54 (0.26).

CONCLUSIONS

All necessary ethical, scientific, clinical and regulatory procedures were put in place to conduct PK studies using enteral and systemic microdosing in two European centres. The pharmacokinetics of a therapeutic dose (mg kg(-1)) and a microdose (ng kg(-1)) in babies between 35 to 127 weeks post-menstrual age. [(14)C]-PARA pharmacokinetic parameters were within a two-fold range after a therapeutic dose or a microdose. Exploratory studies using doses significantly less than therapeutic doses may offer ethical and safety advantages with increased bionalytical sensitivity in selected exploratory paediatric pharmacokinetic studies.

Applied Pharmaceutical Analysis India 2014 conference report

Applied Pharmaceutical Analysis (APA) India 23-26 February 2014, Ahmedabad, India The fifth Applied Pharmaceutical Analysis (APA) India meeting was held in February 2014 at Hyatt Ahmedabad, India. With the theme of 'The Science of Measurement: Current status and Future trends in Bioanalysis, Biotransformation and Drug Discovery Platforms', the conference was attended by over 160 delegates. The agenda comprised advanced and relevant research topics in the key areas of bioanalysis and drug metabolism. APA India 2014 provided a unique platform for networking and professional linking to participants, innovators and policy-makers. As part of the global research community, APA India continues to grow and receive considerable attention from the drug discovery and development community of India.

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.

Therapeutic drug monitoring by dried blood spot: progress to date and future directions

This article discusses dried blood spot (DBS) sampling in therapeutic drug monitoring (TDM). The most important advantages of DBS sampling in TDM are the minimally invasive procedure of a finger prick (home sampling), the small volume (children), and the stability of the analyte. Many assays in DBS have been reported in the literature over the previous 5 years. These assays and their analytical techniques are reviewed here. Factors that may influence the accuracy and reproducibility of DBS methods are also discussed. Important issues are the correlation with plasma/serum concentrations and the influence of hematocrit on spot size and recovery. The different substrate materials are considered. DBS sampling can be a valid alternative to conventional venous sampling. However, patient correlation studies are indispensable to prove this. Promising developments are dried plasma spots using membrane and hematocrit correction using the potassium concentration.

Procedures and practices for the validation of bioanalytical methods using dried blood spots: a review

Dried blood spot (DBS) sampling, the collection of whole blood samples on paper, is an emerging technique used for bioanalytical methods. Several analytical challenges, such as possible effects of spotting volume, hematocrit and spot inhomogeneity are identified for these methods, however, no regulatory-based guidelines for the specific validation of DBS-based assays are available hitherto. To date, 68 validation reports concerning methods for the quantitative determination of drugs in human DBS could be traced in the literature, with large differences in the extensiveness of the reported validations. This review aims to present an overview of these published validations. Additionally, the different challenges of DBS-based assays are discussed and recommendations on how to perform validation tests addressing these challenges are provided.

Bisoprolol, ramipril and simvastatin determination in dried blood spot samples using LC-HRMS for assessing medication adherence

The use of dried blood spot (DBS) collection cards was investigated for the quantification of three therapeutic drugs used in cardiovascular therapy for assessing medication adherence. A liquid chromatography-high resolution mass spectrometry (LC-HRMS) method was developed and validated for the determination of bisoprolol, ramipril and simvastatin. Whole blood spiked with target analytes was used to produce 30 μl blood spots on specimen collection cards. An 8mm disc was cut from the dried blood spot and extracted using methanol: water (70:30, v/v) containing the internal standard, atenolol. Extracts were vortexed, sonicated and then centrifuged. Gradient chromatographic elution was achieved using a Zorbax Eclipse C18 HD 100 mm × 2.1 mm, 1.8 μm pore size column and a mobile phase flow rate of 0.6 ml/min and the column oven temperature at 40 °C with a run time of 3 min. MS detection was carried out in electrospray positive ion mode for the three target drugs and for the IS. Drug recoveries from spiked blood spots were ≥ 92% for bisoprolol and ramipril and ~43% for simvastatin and the drugs were stable in DBS for at least 12 weeks. Validation of the LC-HRMS method showed good linearity and the accuracy (relative error) and precision (coefficient of variation) values were within the pre-defined limits of ≤ 15% at all concentrations. Matrix effects and the effects of different volumes of blood applied to the collection card were investigated. The LC-HRMS method successfully identified control volunteers who were known to be either adherent or non-adherent. There were no false positives from volunteers taking other cardiovascular drugs or from volunteers receiving no medication.

Application of DBS sampling in combination with LC–MS/MS for pharmacokinetic evaluation of a compound with species-specific blood-to-plasma partitioning

Background: Dried blood spot (DBS) sampling in combination with LC–MS/MS has been used increasingly in drug discovery for quantitative analysis to support pharmacokinetic (PK) studies. In this study, we assessed the effect of blood-to-plasma (B:P) partitioning on the bioanalytical performance and PK data acquired by DBS for a compound AMG-1 with species and concentration-dependent B:P ratio. Results: B:P partitioning did not adversely affect bioanalytical performance of DBS for AMG-1. For rat, (B:P ratio of 0.63), PK profiles from DBS and plasma methods were comparable. For dog, concentration-dependence of B:P ratio was observed both in vivo and in vitro. Additional studies demonstrated concentration-dependence of the compound’s unbound fraction in plasma, which may contribute to the concentration-dependence of the B:P ratio. Conclusion: DBS is a promising sampling technique for preclinical pharmacokinetic studies. For compounds with high B:P ratio, caution needs to be applied for data comparison and interpretation between matrices.

Quantitative determination of atenolol in dried blood spot samples by LC-HRMS: a potential method for assessing medication adherence

The use of blood spot collection cards was investigated as a means of obtaining small volume samples for the quantification of therapeutic drugs for assessing medication adherence. A liquid chromatography-high resolution TOF mass spectrometry (LC-HRMS) method, based on the measurement at the accurate mass to charge ratio of the target analyte, was used to ensure specificity for atenolol in the dried blood spot (DBS) samples. A working method was developed and validated. For the preparation of DBS samples whole blood spiked with analyte was used to produce 30 μl blood spots on specimen collection cards. A 5mm disc was cut from the dried blood spot and extracted using methanol:water (60:40, v/v) containing the internal standard, atenolol-d(7). Extracts were vortexed, sonicated and then centrifuged. Gradient chromatographic elution was achieved using an Ascentis Express C18 100mm×2.1mm column and a mobile phase flow rate of 0.2 ml/min and the column oven temperature at 30 °C. MS detection was carried out in electrospray positive ion mode for target ions at accurate mass m/z 267.1703 for atenolol and 274.2143 for the IS. Drug extraction efficiency from spiked blood spots was demonstrated to be 96±5% and the drug was stable in DBS for at least 10 weeks. The developed LC-HRMS method was linear within the tested calibration range of 25-1500 ng/ml and validation showed the accuracy (relative error) and precision (coefficient of variation) values were within the pre-defined limits of ≤ 5% at all concentrations with a limit of quantification of 25 ng/ml. Factors with potential to affect drug quantification measurements such as the matrix effects, volume of blood applied onto the collection card and effect of different sampling cards were investigated. The developed LC-HRMS method was applied to blood spots on sampling card taken from adult healthy volunteers previously administered a 50mg atenolol tablet and a DBS concentration-time profile was obtained for atenolol. Requiring only a micro volume (30 μl) blood sample for analysis, the developed DBS based assay has the potential to assess patient adherence to atenolol.

Silica coated paper substrate for paper-spray analysis of therapeutic drugs in dried blood spots

Paper spray is a newly developed ambient ionization method that has been applied for direct qualitative and quantitative analysis of biological samples. The properties of the paper substrate and spray solution have a significant impact on the release of chemical compounds from complex sample matrices, the diffusion of the analytes through the substrate, and the formation of ions for mass spectrometry analysis. In this study, a commercially available silica-coated paper was explored in an attempt to improve the analysis of therapeutic drugs in dried blood spots (DBS). The dichloromethane/isopropanol solvent has been identified as an optimal spray solvent for the analysis. The comparison was made with paper spray using chromatography paper as substrate with methanol/water as solvent for the analysis of verapamil, citalopram, amitriptyline, lidocaine, and sunitinib in dried blood spots. It has been demonstrated that the efficiency of recovery of the analytes was notably improved with the silica coated paper and the limit of quantitation (LOQ) for the drug analysis was 0.1 ng mL(-1) using a commercial triple quadrupole mass spectrometer. The use of silica paper substrate also resulted in a sensitivity improvement of 5-50-fold in comparison with chromatography papers, including the Whatman ET31 paper used for blood cards. Analysis using a hand-held miniature mass spectrometer Mini 11 gave LOQs of 10-20 ng mL(-1) for the tested drugs, which is sufficient to cover the therapeutic ranges of these drugs.

Microassay of drugs and modern measurement techniques

Details of the development of conventional analytical methods for the determination of drugs in pediatric plasma/serum samples via microassays are presented. Examples of the development of small-volume sampling and the use of the newer detection systems such as LC/MS/MS for enhanced detection are presented. Dried blood spot sampling has conventionally been used for the study of inborn errors of metabolism using Guthrie cards. Limited applications in the area of drug-level determination, for example, in therapeutic drug monitoring had been reported but the methodology had not been widely used up until relatively recently. In the last few years, there has been a resurgence of interest in this methodology for drug-level determinations, and examples of drug analysis in pediatric and neonatal patients where the small-volume samples are particularly useful are presented. The application of the methodology in pharmacokinetic/pharmacodynamic studies is discussed. The utilization of solid-phase microextraction and stir bar sorptive extraction in drug analysis is presented. Clinical applications of these methodologies are reported including the development of in vivo solid-phase microextraction.

Validation of a high-sensitivity assay for zatebradine in dried blood spots of human blood at pg/ml concentrations using HILIC–MS/MS

Background: One of the main reasons for the increased popularity of dried blood spots (DBS) is related to the 3Rs principles (replacement, refinement and reduction) for animal use in drug development. The small blood volume collected using this technique may have a significant impact on the assay sensitivity. An approach that made use of hydrophilic interaction chromatography (HILIC) to enhance the LC–MS assay sensitivity was explored and optimized for a tool compound. Results: A very high-sensitivity assay in dried spots of human blood was validated in the range of 5 to 5000 pg/ml. The use of HILIC increased LC–MS sensitivity up to fivefold compared with other reversed phase chromatographic methods. Conclusion: The good compatibility of the DBS extracts with HILIC and the results of the assay validation for zatebradine at a very low LLOQ demonstrate the high potential and the high performance of this approach.