Traditional Blood Sampling Research Articles

Unlocking the Potential of Dried Blood Spot Sampling for SARS-CoV-2 Antibody Detection: A Pathway to Efficient Pandemic Surveillance

Summary: The current SARS-CoV-2 pandemic has exerted unprecedented pressure on global healthcare systems, with an urgent demand for widespread testing to monitor virus spread and contribute to disease control. Aim: This study aimed to validate the use of Dried Blood Spot (DBS) sampling for analyzing the immune response to SARS-CoV-2 infection, employing an accessible enzyme-linked immunosorbent assay (ELISA) for detecting IgG antibodies. Methodology: Traditional venous blood sampling presents several challenges, including discomfort to patients, risk of healthcare provider exposure, and the need for specialized equipment, which can limit mass testing capabilities. Our research involved the comparison of DBS and venous blood samples from 170 individuals, all of whom had PCR-confirmed SARS-CoV-2 infection, to assess the efficacy of DBS for seroprevalence studies and vaccine response evaluation. Results: Our results confirmed that DBS sampling could detect SARS-CoV-2 IgG antibodies with 100% accuracy, showcasing perfect agreement (Cohen's k value of 1.00) between DBS and venous serum samples in detecting the viral antibodies. However, the analysis indicated no significant correlation between the antibody levels in the two sampling methods. Conclusion: These results suggest that DBS is a viable, rapid alternative for serological studies, offering a solution to current testing limitations and enhancing our public health approach to combating future pandemics.

Non-enzymatic Determination of Glucose in Artificial Urine Using 3D-µPADs through Silver Nanoparticles Formation

Patients with diabetes often experience blood glucose fluctuations, making monitoring crucial. Traditional blood sampling methods pose risks of infection and pain. An alternative non-invasive approach using urine tests has been explored. Recent studies highlight microfluidic paper-based analytical devices (µPADs) as convenient, simple, and easily fabricated tools for non-invasive glucose measurement. This study aims to develop a concept of measuring glucose in artificial urine using 3D-µPADs in a non-enzymatic manner by utilizing glucose as a reducing agent for silver nanoparticle (AgNPs) formation. Embedding three-dimensional connectors in µPADs links the sample and detection zones to limit reagent mixing and improve glucose detection resolution. The optimal conditions were NaOH 10 M, starch 1%, and AgNO3 30 mM, with sample and detection zone volumes of 10 and 9 µL, respectively. The fifth reaction sequence involved AgNO3 in the detection zone and a solution of glucose, NaOH, and starch in the sample zone at 1:1:1 volume ratio. The reagent drying time was 15 min, with immobilization once and reaction time of 9 min. The method showed excellent linearity (R2 = 0.9905), precision (%RSD = 4.27%), accuracy (77.32–92.58%), and limit of detection (11.11 mg/dL).

Salivary Diagnostics in Oral and Systemic Diseases - A Review

Salivary diagnostics, an emerging field in medical research, leverages the analysis of saliva for non- invasive detection, monitoring, and management of various diseases. This abstract explores the potential of saliva as a diagnostic fluid, highlighting its advantages such as ease of collection, cost-effectiveness, and patient acceptability compared to traditional blood or tissue sampling. Key biomarkers identified in saliva include proteins, nucleic acids, and metabolites that reflect systemic health conditions, oral diseases, infectious agents, and even systemic diseases like cancer and diabetes. Advances in technology, such as biosensors and genomic analysis, enhance the sensitivity and specificity of salivary diagnostics, paving the way for personalized medicine and early intervention strategies. Challenges including standardization, variability in saliva composition, and regulatory approval are also discussed, underscoring the need for further research and clinical validation. Salivary diagnostics holds promise as a valuable tool in future healthcare, potentially transforming how diseases are diagnosed and managed globally.

Non-invasive Blood Glucose Monitoring System

The project presents a novel approach to blood glucose monitoring, offering a non-invasive and pain-free method for individuals with diabetes to track their glucose levels. The system utilizes advanced sensor technology coupled with signal processing techniques to detect glucose levels in the body without the need for traditional needle pricking. The key components of the system include a power supply, voltage regulator, ESP32 microcontroller, LCD display, photo sensor, amplifier circuit, and linearization circuit, all seamlessly integrated to provide accurate and real-time glucose readings. This breakthrough technology holds great promise in revolutionizing diabetes management, enhancing the quality of life for millions of affected individuals.By placing the sensor on the individual’s hand, the Glucometer system employs a combination of photonic and electronic principles to non-invasively measure glucose levels. The photo sensor captures specific wavelengths of light that interact with glucose molecules within the tissue, generating a signal proportional to the glucose concentration. This signal is then amplified and processed through the integrated circuits, ensuring accurate linearization and calibration. The ESP32 microcontroller orchestrates these operations, facilitating seamless communication with the LCD display to present the glucose reading in a clear and user-friendly format.The Glucometer’s innovative design eliminates the discomfort associated with traditional blood sampling methods, making it a highly accessible and convenient tool for diabetes management. The system’s efficiency in providing accurate glucose readings without the need for invasive procedures represents a significant advancement in healthcare technology. With further development and refinement, the Glucometer holds the potential to significantly enhance the daily lives of individuals living with diabetes, offering a reliable and painless means of monitoring blood glucose levels.

Wearable microneedle-based colorimetric and fluorescence sensing for transdermal diagnostics

Interstitial fluid is a readily accessible source of biomarkers for various diseases, providing a less invasive and more convenient option than traditional blood or tissue sampling methods. Microneedle-based point-of-care testing devices have gained significant interest due to their potential for direct detection of target analytes in ISF, accomplished through minimally invasive penetration of the stratum corneum. Thus, microneedle-based devices can be considered as adhesive tools for diagnostic sensing and therapeutic drug administration. Microneedle-based colorimetric and fluorescence sensing has the potential to revolutionize disease diagnosis and monitoring, offering a rapid, highly sensitive, specific, and cost-effective alternative to traditional methods. These devices enable the detection of low levels of biomarkers in the collected fluid, which is particularly important in situations requiring prompt diagnosis and treatment. This review covers the types of microneedles and their fabrication methods, the detection principles of microneedle-based colorimetric and fluorescence sensing, as well as their key applications, advantages, and limitations. Additionally, the review explores ways to overcome current limitations and improve the performance, as well as future perspectives for the development of microneedle-based devices.

Recent Progress on Non-invasive Wearable Epidermal Biosensors

Wearable biosensors have the potential to provide valuable information about our physiological states and transform traditional healthcare. Compared to traditional blood sampling, on-body analysis of non-invasive biofluids can offer continuous and painless monitoring of relevant biomarkers. Recent developments in epidermal sensors feature integrated systems capable of sensing multiple factors while providing easy readout and great skin conformity. Innovative solutions based on advanced material fabrication and novel designs have also emerged to address challenges such as power, sensor sensitivity and selectivity, and communication. As a result, more possibilities have emerged to develop sophisticated integrations with more functionalities, optimized skin conformity, and less disruption of daily routine. While sensing performance and functions continue to improve, attention should also be drawn to practical problems such as biofouling, contamination, and complex composition dynamics. Moreover, although past and current research have highlighted studies investigating the use of sweat in diagnostics, more evidence of correlations between sweat biomarker levels and physiological conditions is needed to promote the utility of these systems.

Current Understanding of Dried Spots Platform for Blood Proteomics

Abstract: Dry Blood Spots (DBS) have been used in combination with liquid chromatography-mass spectrometry for targeted proteomics to identify sensitive and specific novel biomarkers. DBS presents several advantages over other traditional blood sampling methods. This review discusses the past, present and future of the technology, focusing on studies with clinical and population relevance. Arguments for and against DBS are presented by discussing technological advances, particularly those related to Mass Spectrometry (MS) and Multiple Reaction Monitoring (MRM), sample preparation issues, disease biomarkers, pharmacokinetics, and pharmacodynamics. There will be a focus on proteomic studies that rely on DBS as a sampling method. In this context, numerous studies on the diagnosis and treatment of several diseases. To date, proteomic reports of studies using DBS have shown that DBS can facilitate diagnosis and prognosis. DBS offers several advantages that make it a viable option for many fields. Moreover, some of its disadvantages can be easily overcome through automation to increase reproducibility and reduce protocol variability and standardization of parameters such as the volume of sample used. Within this context, here we propose to review the advantages and disadvantages of using DBS for blood proteomics and provide an understanding of how current DBS-based protocols are being conducted for future standardization and protocol optimization.

The use of dried blood spot cards to assess serologic responses of individuals vaccinated against measles, hepatitis A, tetanus, influenza and varicella zoster.

Traditional blood sampling by venipuncture is cumbersome and relatively expensive. Dried blood spot (DBS) sampling is desirable because of its ease of sample collection, transportation and storage. It has been used in clinical diagnosis but not been thoroughly studied for the potential use to assess the immune status of individuals following natural infection or preventive vaccination. The goal of this study was to compare DBS to traditional blood samplings in detection of antibodies in individuals vaccinated against measles, hepatitis A, tetanus, influenza and varicella zoster. Enzyme linked immunosorbent assay (ELISA) was used to test DBS eluates and serum samples for antibodies against measles, varicella, tetanus and hepatitis A. Sensitivities, specificities, and correlation coefficients were evaluated to compare optical density (OD) values of paired serum and DBS samples. The long-term stability of DBS samples at different temperatures was assessed using simulated immune measles blood. DBS OD was highly correlated with serum OD for antibodies to measles (r = 0.93), varicella (r = 0.82), and tetanus (r = 0.91). Sensitivities of DBS OD ranged from 86–99% and specificities ranged from 96–100% using cut-offs established by each assay. By contrast, the hepatitis A data showed a low sensitivity (31%) and weak correlation (r = 0.14) between DBS and serum samples. Antibody titers in serum samples for anti-influenza A (H1N1 and H3N1) failed to correlate in DBS eluates in HAI and MN assays. DBS samples were stable for 4 weeks when stored at room temperature and for 6 months at 4°C. DBS sampling was sensitive, specific, and highly correlated with traditional venipuncture sampling in detection of antibodies against measles, tetanus and varicella zoster, but not hepatitis A and influenza. Thus, the success of using DBS sampling to assess the antibody levels in immunized individuals may be dependent on the pathogens and the development of the assay used.

Therapeutic Drug Monitoring of Tyrosine Kinase Inhibitors Using Dried Blood Microsamples.

Therapeutic drug monitoring (TDM) of tyrosine kinase inhibitors (TKIs) is not yet performed routinely in the standard care of oncology patients, although it offers a high potential to improve treatment outcome and minimize toxicity. TKIs are perfect candidates for TDM as they show a relatively small therapeutic window, a wide inter-patient variability in pharmacokinetics and a correlation between drug concentration and effect. Moreover, most of the available TKIs are susceptible to various drug-drug interactions and medication adherence can be checked by performing TDM. Plasma, obtained via traditional venous blood sampling, is the standard matrix for TDM of TKIs. However, the use of plasma poses some challenges related to sampling and stability. The use of dried blood microsamples can overcome these limitations. Collection of samples via finger-prick is minimally invasive and considered convenient and simple, enabling sampling by the patients themselves in their home-setting. The collection of small sample volumes is especially relevant for use in pediatric populations or in pharmacokinetic studies. Additionally, working with dried matrices improves compound stability, resulting in convenient and cost-effective transport and storage of the samples. In this review we focus on the different dried blood microsample-based methods that were used for the quantification of TKIs. Despite the many advantages associated with dried blood microsampling, quantitative analyses are also associated with some specific difficulties. Different methodological aspects of microsampling-based methods are discussed and applied to TDM of TKIs. We focus on sample preparation, analytics, internal standards, dilution of samples, external quality controls, dried blood spot specific validation parameters, stability and blood-to-plasma conversion methods. The various impacts of deviating hematocrit values on quantitative results are discussed in a separate section as this is a key issue and undoubtedly the most widely discussed issue in the analysis of dried blood microsamples. Lastly, the applicability and feasibility of performing TDM using microsamples in a real-life home-sampling context is discussed.

Comparison of pulse oximetry and earlobe blood gas with CO-oximetry in children with sickle cell disease: a retrospective review

ObjectivesTo investigate the agreement between pulse oximetry (SpO2) and oxygen saturation (SaO2) measured by CO-oximetry on arterialised earlobe blood gas (EBG) in children and adolescents with sickle cell disease (SCD).Design...

Analysis of the Heterogeneous Distribution of Amiloride and Propranolol in Dried Blood Spot by UHPLC-FLD and MALDI-IMS.

Dried blood spot (DBS) has lately experienced an increase in its use in bioanalysis due to its several advantages compared with traditional blood sampling methods. Nevertheless, the use of DBS with quantitative purposes is hindered by the heterogeneous distribution of some compounds in the supporting matrix and the dependence of the response on different factors, such as the hematocrit, blood volume, and sampling position. In this study the effect of those factors in the analytical response was investigated by ultra high performance liquid chromatography coupled to fluorescence detection, using amiloride and propranolol as model compounds. The results showed a heterogeneous and drug-dependent distribution of the compounds in the blood spot. While amiloride concentration was higher in the center, propranolol concentration was higher in the periphery of the spot. Besides, the influence of the hematocrit on the quantitative results was observed. MALDI mass spectrometry imaging (MALDI-IMS) has allowed study of the distribution of the two cardiovascular drugs when they were placed in the DBS card using water:methanol solutions, demonstrating that they followed a similar distribution pattern as in blood. This work has showed the potentiality of the MALDI-IMS technique to predict the distribution of the drugs in the DBS card.

Development and clinical applications of the dried blood spot method for therapeutic drug monitoring of anti-epileptic drugs.

Anti-epileptic drugs (AEDs) have various pharmacokinetic profiles, inter-individual variabilities, high possibilities of drug-drug interactions and narrow therapeutic indices. To provide optimal treatment for patients, therapeutic drug monitoring (TDM) is necessary. However, TDM requires sufficient quantities of blood samples to measure drug concentrations. Therefore, TDM could be a burden, particularly in paediatric cases. A good alternative that overcomes these disadvantages is the dried blood spot (DBS) method, which is simple, convenient to use and less invasive, requiring a lower quantity of blood than traditional blood sampling methods. However, the DBS method is affected by haematocrit (Hct) levels to varying extents depending on the drug properties. In addition, different papers with varying characteristics are available for use when applying the DBS method. Therefore, it has not yet been applied to TDM in clinical practice. To achieve this, several steps are required, including method development, method validation and clinical validation. Currently, the development status of the DBS method is different for each AED and unclear. Therefore, we assessed the development status of the following 19 AEDs in 26 studies: lamotrigine, valproic acid, levetiracetam, phenytoin, topiramate, carbamazepine, carbamazepine epoxide, gabapentin, phenobarbital, pregabalin, clobazam, clonazepam, ethosuximide, felbamate, monohydroxycarbamazepine, nitrazepam, rufinamide, vigabatrin and zonisamide. Among them, carbamazepine, lamotrigine, topiramate and valproic acid have been developed such that they are nearly available for TDM. In addition, Whatman 903 Protein Saver Cards and concentration analysis by liquid chromatography with triple quadrupole mass spectrometer were used most often.

Prognostic value of suPAR and hs-CRP on cardiovascular disease

Background and aimsStudies have shown that soluble urokinase Plasminogen Activator Receptor (suPAR) and CRP (both inflammatory markers) and coronary artery calcification (CAC) are independent risk predictors for cardiovascular (CV) disease. The aim of this study is to assess whether suPAR and CRP have an increased predictive prognostic value beyond the traditional CV risk factors and the CAC score. MethodsA population sample of 1179 subjects, free of CV disease was included. The subjects underwent traditional CV risk evaluation, CAC assessment and blood sampling for suPAR and CRP. CV events were extracted from The Danish National Patient Register after 6.5 years. The additive values of suPAR and CRP were evaluated by unadjusted Kaplan Meier analysis, adjusted hazard ratio and ROCAUC models. Results1179 participants (47.6% males, mean age 55 years) were included. 73 events occurred. In Kaplan Meier analyses, suPAR and CRP were significantly associated with CV events (p = 0.03 and p = 0.002). Adjusted for the CV risk factors and the CAC score, the hazard ratios for suPAR and CRP were 1.17 (95% confidence interval [CI] 1.01–1.34) and 1.04 (95% CI 1.01–1.06), respectively. suPAR was associated with a substantial risk among women (2.03; 95% CI 1.45–2.84) and 60-year-old subjects (1.44; 95% CI 1.09–1.90). By ROCAUC, neither suPAR nor CRP provided significant estimates (0.7100 and 0.7054) compared to the traditionally CV risk factors (0.6952, p = 0.24 and p = 0.16) and CAC score (0.7481, p = 0.33 and p = 0.32). ConclusionsAdjusted for traditional CV risk factors and CAC score, suPAR and CRP were of minor importance in risk prediction.

Analytical and Clinical Validity Study of FirstStepDx PLUS: A Chromosomal Microarray Optimized for Patients with Neurodevelopmental Conditions.

Introduction:Chromosomal microarray analysis (CMA) is recognized as the first-tier test in the genetic evaluation of children with developmental delays, intellectual disabilities, congenital anomalies and autism spectrum disorders of unknown etiology.Array Design:To optimize detection of clinically relevant copy number variants associated with these conditions, we designed a whole-genome microarray, FirstStepDx PLUS (FSDX). A set of 88,435 custom probes was added to the Affymetrix CytoScanHD platform targeting genomic regions strongly associated with these conditions. This combination of 2,784,985 total probes results in the highest probe coverage and clinical yield for these disorders.Results and Discussion:Clinical testing of this patient population is validated on DNA from either non-invasive buccal swabs or traditional blood samples. In this report we provide data demonstrating the analytic and clinical validity of FSDX and provide an overview of results from the first 7,570 consecutive patients tested clinically. We further demonstrate that buccal sampling is an effective method of obtaining DNA samples, which may provide improved results compared to traditional blood sampling for patients with neurodevelopmental disorders who exhibit somatic mosaicism.

MicroRNA-urile salivare ca biomarkeri pentru malignitatea orală

Background. Saliva sampling is a non-invasive, cheap, easy-to-access alternative to traditional tissue and blood sampling. Saliva is an accurate indicator of bodily conditions, and salivary biomarkers may serve as early diagnostic tools. In this study we aimed to validate the salivary expression of a panel of 5 microRNAs, identified from a literature screen as potential noninvasive biomarkers for oral squamous cell carcinoma (OSCC) diagnosis, prediction and therapy monitoring. Materials and methods. The research subjects included patients diagnosed with oral squamous cell carcinoma hospitalized at the Clinic of Oral & Maxillofacial Surgery in Timisoara. The biological samples (saliva) were collected from the patients before the biopsy procedure. We included in this study a group of 4 patients and a control group of 4 individuals without OSCC. For microRNA quantification, we performed reverse transcription using the TaqMan® MicroRNA Reverse Transcription Kit (Thermofisher) followed by quantitative Real-Time PCR (qRTPCR) using TaqMan™ MicroRNA Assays (Thermofisher); all qRT-PCR reactions were performed in triplicate. Results. With the exception of miR-181b, all the investigated microRNAs were found to have deregulated expression in OSCC patients’ saliva. Hsa-miR-137 was found to be up-regulated in the saliva of OSCC patients while hsa-miR-205 was found to be strongly down-regulated. However, we were able to confirm the activation of expression of hsa-miR-127-5b and the strong repression of hsa-miR-375 in the saliva of OSCC patients. The data upon hsa-miR-181 expression in OSCC have been conflicting, ranging from strong down-regulation in tissue samples and possible usage as therapeutic tool to correlation with metastasis propensity; however, we have not detected changes in the expression levels in saliva. Conclusions. Detection of deregulated miRNA biomarkers in saliva samples is a promising noninvasive assay for risk assessment of oral malignancy, which may add value to the histologic diagnosis.

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

IntroductionSerial sampling methods have been used for rat pharmacokinetic (PK) studies for over 20years. Currently, it is still common to take 200–250μL 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 (≤50μL) techniques have been reported as an alternative process for collecting blood samples from rats. MethodsIn 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. ResultsFor 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. DiscussionThe 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.

Paediatricians' opinions of microneedle-mediated monitoring: a key stage in the translation of microneedle technology from laboratory into clinical practice.

Microneedle (MN) arrays could offer an alternative method to traditional drug delivery and blood sampling methods. However, acceptance among key end-users is critical for new technologies to succeed. MNs have been advocated for use in children and so, paediatricians are key potential end-users. However, the opinions of paediatricians on MN use have been previously unexplored. The aim of this study was to investigate the views of UK paediatricians on the use of MN technology within neonatal and paediatric care. An online survey was developed and distributed among UK paediatricians to gain their opinions of MN technology and its use in the neonatal and paediatric care settings, particularly for MN-mediated monitoring. A total of 145 responses were obtained, with a completion response rate of 13.7%. Respondents believed an alternative monitoring technique to blood sampling in children was required. Furthermore, 83% of paediatricians believed there was a particular need in premature neonates. Overall, this potential end-user group approved of the MN technology and a MN-mediated monitoring approach. Minimal pain and the perceived ease of use were important elements in gaining favour. Concerns included the need for confirmation of correct application and the potential for skin irritation. The findings of this study provide an initial indication of MN acceptability among a key potential end-user group. Furthermore, the concerns identified present a challenge to those working within the MN field to provide solutions to further improve this technology. The work strengthens the rationale behind MN technology and facilitates the translation of MN technology from lab bench into the clinical setting.

Potassium-based algorithm allows correction for the hematocrit bias in quantitative analysis of caffeine and its major metabolite in dried blood spots.

Although dried blood spot (DBS) sampling is increasingly receiving interest as a potential alternative to traditional blood sampling, the impact of hematocrit (Hct) on DBS results is limiting its final breakthrough in routine bioanalysis. To predict the Hct of a given DBS, potassium (K(+)) proved to be a reliable marker. The aim of this study was to evaluate whether application of an algorithm, based upon predicted Hct or K(+) concentrations as such, allowed correction for the Hct bias. Using validated LC-MS/MS methods, caffeine, chosen as a model compound, was determined in whole blood and corresponding DBS samples with a broad Hct range (0.18-0.47). A reference subset (n = 50) was used to generate an algorithm based on K(+) concentrations in DBS. Application of the developed algorithm on an independent test set (n = 50) alleviated the assay bias, especially at lower Hct values. Before correction, differences between DBS and whole blood concentrations ranged from -29.1 to 21.1%. The mean difference, as obtained by Bland-Altman comparison, was -6.6% (95% confidence interval (CI), -9.7 to -3.4%). After application of the algorithm, differences between corrected and whole blood concentrations lay between -19.9 and 13.9% with a mean difference of -2.1% (95% CI, -4.5 to 0.3%). The same algorithm was applied to a separate compound, paraxanthine, which was determined in 103 samples (Hct range, 0.17-0.47), yielding similar results. In conclusion, a K(+)-based algorithm allows correction for the Hct bias in the quantitative analysis of caffeine and its metabolite paraxanthine.

Enantioselective pharmacokinetics and cardiovascular effects of nebivolol in L-NAME hypertensive rats

The cardiovascular effects and pharmacokinetics of nebivolol were assessed in N(G)-nitro-l-arginine methyl ester (L-NAME) hypertensive and normotensive control rats. Male Wistar rats were randomly divided to drink tap water (control) or L-NAME solution for 2 weeks. The effects of nebivolol (3 or 10 mg kg(-1) i.v.) on blood pressure (BP), heart rate and BP variability (BPV) were recorded in awake L-NAME and control rats. Short-term and beat-to-beat BPV was assessed by the s.d. and spectral analysis of the BP recordings. Nebivolol pharmacokinetics was studied by means of traditional blood sampling. Nebivolol showed enantioselective pharmacokinetics in both experimental groups; the clearance and the volume of distribution of l-nebivolol were significantly greater than those of the d-enantiomer. The hypotensive response to nebivolol was significantly enhanced in L-NAME rats (Δmean arterial pressure (MAP): -16.1±1.1%, P<0.05 vs. control rats) compared with normotensive animals (ΔMAP: -1.4±2.1%). An analysis of the beat-to-beat BPV showed a greater reduction in VLF BPV in the L-NAME compare with the control rats. Nebivolol significantly reduced the low-frequency/high-frequency ratio in hypertensive L-NAME animals compared with normotensive rats. Short-term BPV was markedly reduced by nebivolol in both experimental groups, although the attenuation of the s.d. of BP recording was greater in L-NAME rats. In conclusion, the hypotensive efficacy of nebivolol is significantly enhanced in L-NAME rats compared with normotensive animals, which is most likely due to a greater reduction in vascular sympathetic activity. Nebivolol markedly attenuated short-term BPV in both experimental groups, suggesting that β-blockers with additional pharmacological actions provide beneficial cardiovascular effects by controlling high BP and its short-term variability.

A new approach for pharmacokinetic studies of natural products: measurement of isoliquiritigenin levels in mice plasma, urine and feces using modified automated dosing/blood sampling system

The present study was undertaken to investigate the pharmacokinetics of isoliquiritigenin (isoLQ) as determined by the automated dosing/blood sampling (ABS) and traditional manual blood sampling techniques in awake and freely moving mice using combined liquid chromatography tandem mass spectrometry. Pharmacokinetic comparison was conducted by allocating mice into two groups; an ABS group (intravenous study and oral studies, n = 5 each) and a manual group (intravenous and oral studies; n = 5 each). Significant differences in pharmacokinetic parameters (area under the curve and clearances) were observed between ABS and manual groups. This could be mainly due to the blood sampling site difference (via heart puncture in traditional manual group and via carotid artery in ABS groups). The low F of isoLQ could be mainly due to a considerable gastrointestinal and/or hepatic first-pass effect and not to incomplete absorption. The driving force for distribution and elimination of drugs is its concentration in the arterial blood. Therefore, the ABS method was found to be a useful drug development tool for accelerating the process of preclinical in vivo studies and for obtaining reliable and accurate pharmacokinetic parameters in mice.