Estimated Plasma Concentration Research Articles

Examining Downstream Effects of Concizumab in Hemophilia A with a Mathematical Modeling Approach

BackgroundTissue factor pathway inhibitor (TFPI) is an anticoagulant protein that inhibits FXa, the TF-FVIIa-FXa complex, and early forms of the prothrombinase complex. Concizumab is a monoclonal antibody that blocks FXa inhibition by TFPI and reduces bleeding in hemophilia. ObjectivesTo examine how concizumab impacts various reactions of TFPI to restore thrombin generation in hemophilia A using mathematical models. MethodsA compartment model was used to estimate plasma concentrations of free concizumab and its complexes with TFPIα and TFPIβ. Concizumab was integrated into a flow-mediated mathematical model of coagulation and a small injury was simulated under hemophilia A conditions. Simulations were then analyzed to determine how concizumab’s blockade of TFPI anticoagulant activities, specifically the inhibition of FXa in plasma and on platelets, inhibition of TF:VIIa at the subendothelium, and prior sequestration of plasma TFPIα to the endothelium via TFPIβ, altered thrombin generation. ResultsConcizumab improved simulated thrombin generation in hemophilia A by simultaneously altering all three mechanisms of TFPI anticoagulant blockade examined. Concizumab sequesters ∼75% of plasma TFPIα through formation of ternary TFPIα-concizumab-TFPIβ-complexes. For all TF levels, reducing the TFPIα plasma concentration had the largest impact on the lag time followed by blocking TFPIα inhibition of TF:VIIa:FXa and subsequently followed by blocking TFPIα inhibition of FXa in plasma and on the platelet surface. ConclusionsThe effectiveness of concizumab is mediated through blockade of TFPI anticoagulant activities in plasma and on multiple physiological surfaces. An important and previously unrecognized function of concizumab was sequestration of plasma TFPIα to the endothelium.

Quantification of Letrozole, Palbociclib, Ribociclib, Abemaciclib, and Metabolites in Volumetric Dried Blood Spots: Development and Validation of an LC-MS/MS Method for Therapeutic Drug Monitoring

Therapeutic drug monitoring (TDM) may be beneficial for cyclin-dependent kinase 4/6 inhibitors (CDK4/6is), such as palbociclib, ribociclib, and abemaciclib, due to established exposure–toxicity relationships and the potential for monitoring treatment adherence. Developing a method for quantifying CDK4/6is, abemaciclib metabolites (M2, M20), and letrozole in dried blood spots (DBS) could be useful to enhance the feasibility of TDM. Thus, an optimized LC-MS/MS method was developed using the HemaXis DB10 device for volumetric (10 µL) DBS collection. Chromatographic separation was achieved using a reversed-phase XBridge BEH C18 column. Detection was performed with a triple quadrupole mass spectrometer, utilizing ESI source switching between negative and positive ionization modes and multiple reaction monitoring acquisition. Analytical validation followed FDA, EMA, and IATDMCT guidelines, demonstrating high selectivity, adequate sensitivity (LLOQ S/N ≥ 30), and linearity (r ≥ 0.997). Accuracy and precision met acceptance criteria (between-run: accuracy 95–106%, CV ≤ 10.6%). Haematocrit independence was confirmed (22–55%),with high recovery rates (81–93%) and minimal matrix effects (ME 0.9–1.1%). The stability of analytes under home-sampling conditions was also verified. Clinical validation supports DBS-based TDM as feasible, with conversion models developed for estimating plasma concentrations (the reference for TDM target values) of letrozole, abemaciclib, and its metabolites. Preliminary data for palbociclib and ribociclib are also presented.

Characterization of effective, simple, and low-cost precipitation methods for depleting abundant plasma proteins to enhance the depth and breadth of plasma proteomics.

Plasma is an abundant source of proteins and potential biomarkers to aid in the detection, diagnosis, and prognosis of human diseases. These proteins are often present at low levels in the blood and difficult to identify and measure due to the large dynamic range of proteins. The goal of this work was to characterize and compare various protein precipitation methods related to how they affect the depth and breadth of plasma proteomic studies. Abundant protein precipitation with perchloric acid (PerCA) can increase protein identifications and depth of plasma proteomic studies. Three acid- and four solvent-based precipitation methods were evaluated. All methods tested provided excellent plasma proteomic coverage (>600 identified protein groups) and detected protein in the low pg/mL range. Functional enrichment analysis revealed subtle differences within and larger changes between the precipitant groups. Methanol-based precipitation outperformed the other methods based on identifications and reproducibility. The methods' performance was verified using eight lung cancer patient samples, where >700 protein groups were measured and proteins with an estimated plasma concentration of ∼10pg/mL were detected. Various protein precipitation agents are amenable to extending the depth and breadth of plasma proteomes. These data can guide investigators to implement inexpensive, high-throughput methods for their plasma proteomic workflows.

Salivary Therapeutic Monitoring of Buprenorphine in Neonates After Maternal Sublingual Dosing Guided by Physiologically Based Pharmacokinetic Modeling.

Opioid use disorder (OUD) during pregnancy is associated with high mortality rates and neonatal opioid withdrawal syndrome (NOWS). Buprenorphine, an opioid, is used to treat OUD and NOWS. Buprenorphine active metabolite (norbuprenorphine) can cross the placenta and cause neonatal respiratory depression (EC 50 = 35 ng/mL) at high brain extracellular fluid (bECF) levels. Neonatal therapeutic drug monitoring using saliva decreases the likelihood of distress and infections associated with frequent blood sampling. An adult physiologically based pharmacokinetic model for buprenorphine and norbuprenorphine after intravenous and sublingual administration was constructed, vetted, and scaled to newborn and pregnant populations. The pregnancy model predicted that buprenorphine and norbuprenorphine doses would be transplacentally transferred to the newborns. The newborn physiologically based pharmacokinetic model was used to estimate the buprenorphine and norbuprenorphine levels in newborn plasma, bECF, and saliva after these doses. After maternal sublingual administration of buprenorphine (4 mg/d), the estimated plasma concentrations of buprenorphine and norbuprenorphine in newborns exceeded the toxicity thresholds for 8 and 24 hours, respectively. However, the norbuprenorphine bECF levels were lower than the respiratory depression threshold. Furthermore, the salivary buprenorphine threshold levels in newborns for buprenorphine analgesia, norbuprenorphine analgesia, and norbuprenorphine hypoventilation were observed to be 22, 2, and 162 ng/mL. Using neonatal saliva for buprenorphine therapeutic drug monitoring can facilitate newborn safety during the maternal treatment of OUD using sublingual buprenorphine. Nevertheless, the suitability of using adult values of respiratory depression EC 50 for newborns must be confirmed.

Qualitative and quantitative concentration-response modelling of gene co-expression networks to unlock hepatotoxic mechanisms for next generation chemical safety assessment.

Next generation risk assessment of chemicals revolves around the use of mechanistic information without animal experimentation. In this regard, toxicogenomics has proven to be a useful tool to elucidate the underlying mechanisms of adverse effects of xenobiotics. In the present study, two widely used human in vitro hepatocyte culture systems, namely primary human hepatocytes (PHH) and human hepatoma HepaRG cells, were exposed to liver toxicants known to induce liver cholestasis, steatosis or necrosis. Benchmark concentration-response modelling was applied to transcriptomics gene co-expression networks (modules) to derive benchmark concentrations (BMCs) and to gain mechanistic insight into the hepatotoxic effects. BMCs derived by concentration-response modelling of gene co-expression modules recapitulated concentration-response modelling of individual genes. Although PHH and HepaRG cells showed overlap in deregulated genes and modules by the liver toxicants, PHH demonstrated a higher responsiveness, based on the lower BMCs of co-regulated gene modules. Such BMCs can be used as transcriptomics point of departure (tPOD) for assessing module-associated cellular (stress) pathways/processes. This approach identified clear tPODs of around maximum systemic concentration (Cmax) levels for the tested drugs, while for cosmetics ingredients the BMCs were 10-100-fold higher than the estimated plasma concentrations. This approach could serve next generation risk assessment practice to identify early responsive modules at low BMCs, that could be linked to key events in liver adverse outcome pathways. In turn, this can assist in delineating potential hazards of new test chemicals using in vitro systems and used in a risk assessment when BMCs are paired with chemical exposure assessment.

A 5-year retrospective study of amisulpride steady-state plasma concentration in patients with schizophrenia in real-life settings based on therapeutic drug monitoring data.

Here, we present a retrospective analysis of the last 5 years' data collected in real-life settings as direct evidence to evaluate the optimal therapeutic window of amisulpride (AMI) for psychiatric patients. Retrospective analysis of the therapeutic drug monitoring (TDM) results of AMI in outpatients and inpatients were obtained from the Xi'an Mental Health Center from 2017 to 2021. The interquartile (P25-P75) AMI concentrations ranged 212.20-574.25ng/mL. The results showed that the proportion of outpatients who received TDM once was significantly higher than that of inpatients who received TDM once (P<0.001), whereas the reverse was true for those who experienced TDM more than twice (P<0.001). Higher estimated plasma concentrations were identified in inpatients, female patients, and patients over 59 years of age. Nearly 57.21% of the samples had high concentrations (>320ng/mL). The optimal therapeutic reference range for AMI may require reconstruction to guide the use of AMI for the treatment of schizophrenia.

Development and validation of a liquid chromatographic-tandem mass spectrometric assay for the quantification of cabotegravir and rilpivirine from dried blood spots

BackgroundDried blood spots (DBS) have been utilized as a blood plasma alternative for therapeutic drug monitoring and pharmacologic analysis. There are analytical and physiochemical considerations in bridging drug concentrations from plasma to DBS. Recently, the long-acting antiretroviral cabotegravir (CAB) has been approved for HIV prevention, and a co-packaged regimen of long-acting CAB and rilpivirine (RPV) has been approved for HIV treatment. Measurement of these drugs in blood collected as DBS may offer increased capacity and flexibility in translational applications. MethodsWhole blood was spiked with CAB and RPV and spotted on DBS cards. Following extraction and addition of isotopically labeled internal standards, samples were subjected to liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis. The method was validated according to regulatory recommendations, and the assay was evaluated in remnant samples from an HIV prevention trial in which paired DBS and plasma samples were collected. ResultsDBS CAB and RPV concentrations were linear from 25 to 20,000 ng/mL and 2–2500 ng/mL, respectively. Precision, accuracy, and matrix effect results were acceptable. DBS RPV demonstrated stability under all tested conditions; DBS CAB showed mean biases of − 23.5% when stored at room temperature for 36 days, and − 18.0% at 40 °C and 100% humidity for two days. DBS measurements for CAB and RPV were an average 54.0% and 14.1% lower, respectively, as compared to paired plasma samples. Derived conversion factors of 1.79 and 1.16 were applied to DBS CAB and RPV measurements, respectively, to estimate plasma concentrations. Estimated plasma CAB and RPV concentrations showed mean biases of 2.2% and 0.6%, respectively. In a CAB clinical trial, application of the conversion factor resulted in agreement between estimated plasma CAB concentrations from DBS and plasma CAB concentrations (y = 1.08x - 79.2, r = 0.932; mean bias of −3.2%; 95% CI: −48.2% to 41.9%). ConclusionsWe developed and validated a novel LC-MS/MS assay for the quantification of CAB and RPV from DBS, and identified conversion factors to estimate plasma concentrations from spotted blood.

Quantitation of meropenem in dried blood spots using microfluidic-based volumetric sampling coupled with LC-MS/MS bioanalysis in preterm neonates

Meropenem, a carbapenem antibiotic, has been used for empirical and definitive therapy of severe infections for many years. Therapeutic drug monitoring (TDM) plays an indispensable role in the individualization of meropenem particularly in the preterm neonates, a population in which adjusting proper dosages has always been one of the most challenging tasks for their growth changes. In this report, a simple and accurate method for the quantitative analysis of meropenem in dried blood spot (DBS) samples by LC-MS/MS was developed. The traditional DBS drawbacks were conquered in this study by combining microfluidic-based volumetric sampling, shorten drying procedure, and sensitive detection. Moreover, the on-card stability of meropenem was improved obviously. The DBS-based method validation included hematocrit (Hct) effect, selectivity, carry-over, linearity, accuracy, precision, matrix effect, recovery and stability (high temperature and humidity). The calibration linear range of meropenem was 0.3–100 µg/mL. The acceptance criteria of accuracy (relative error < 4.53 %) and precision (coefficient of variation < 8.63 %) were met in all levels of quality control samples. The DBS samples was stable at 40 °C for 12 h, room temperature for 1 day, 4 °C for 7 days, −20 °C for 14 days and −40 °C for 30 days, respectively. A good correlation was observed between DBS concentration and plasma concentration of meropenem. There was 93.4 % of the samples between estimated plasma concentration and plasma concentration within 20 % of the mean of concentration, and no significant Hct effect was observed on the quantification. It has been successfully applied to samples derived from preterm neonates with severe infections. The supported data indicated that the DBS-based method using microfluidic-based volumetric sampling could be an alternative strategy to carry on TDM of meropenem in preterm neonates, with satisfactory performance and logistics advantages.

Applicability of vancomycin, meropenem, and linezolid in capillary microsamples vs. dried blood spots: A pilot study for microsampling in critically ill children.

Therapeutic drug monitoring (TDM) has been shown to be clinically beneficial for critically ill patients. However, this is a burden for neonates or children with small circulating blood volumes. Here, we aimed to develop and validate a microsampling TDM platform (including dried blood spots (DBS) and capillary microsamples (CMS)) for the simultaneous quantification of vancomycin, meropenem, and linezolid. Paired DBS and CMS samples were obtained from an intensive care unit (ICU) to evaluate its clinical application. Estimated plasma concentrations (EPC) were calculated from DBS concentrations. Agreement between methods was evaluated using Deming regression and Bland-Altman difference plots. The microsampling methods validation showed excellent reliability and compatibility with the analysis of the sample matrix and hematocrit range of the studied population. The DBS and CMS accuracy and precision results were within accepted ranges and samples were stable at room temperature for at least 2 days and 8 h, respectively. Hematocrit had no impact on CMS, but sightly impacted DBS measurements. The CMS and DBS antibiotic concentrations correlated well (r > 0.98). The drug concentration ratio in DBS samples to that in CMS was 1.39 for vancomycin, 1.34 for meropenem, and 0.94 for linezolid. The EPC calculated from the DBS using individual hematocrit ranges presented comparable absolute values for vancomycin (slope: 1.06) and meropenem (slope: 1.04), with a mean of 98% and 99% of the measured CMS concentrations, respectively. This study provides a microsampling TDM platform validated for clinical use for a rapid quantification of three antibiotics and is suitable for real-time TDM-guided personalization of antimicrobial treatment in critically ill children.

Development and Validation of a Simple Method for Simultaneously Measuring the Concentrations of BCR-ABL and Bruton Tyrosine Kinase Inhibitors in Dried Blood Spot (DBS): A Pilot Study to Obtain Candidate Conversion Equations for Predicting Plasma Concentration Based on DBS Concentration.

Dried blood spots (DBSs) are promising candidates for therapeutic drug monitoring. In this study, a simple method for the simultaneous measurement of tyrosine kinase inhibitors (TKIs), including bosutinib, dasatinib, ibrutinib, imatinib, nilotinib, and ponatinib, using DBS was developed and validated. The prediction of the plasma concentration of TKIs based on the TKI concentrations in the DBS was assessed using the developed measurement method. DBS was prepared using venous blood on Whatman 903 cards. One whole DBS sample containing the equivalent of 40 μL of blood was used for the analysis. The analytical method was validated according to the relevant guidelines. For clinical validation, 96 clinical samples were analyzed. The regression equation was derived from a weighted Deming regression analysis, and correction factors for calculating the estimated plasma concentrations (EPCs) of the analytes from their concentrations in the DBS and the predictive performance of EPC were evaluated using 2 conversion equations. This method was successfully validated. Hematocrit had no significant effect on the method's accuracy or precision. Ibrutinib was stable in the DBS for up to 8 weeks at room temperature, whereas all BCR-ABL TKIs were stable for 12 weeks. All BCR-ABL TKIs exhibited similar predictive performance for EPCs using both calculation methods. Good agreement between EPCs and the measured plasma concentrations of bosutinib, imatinib, and ponatinib was observed with both conversion equations. However, Bland-Altman analysis showed that blood sampling time affected the EPC accuracy for dasatinib and nilotinib. A simple method for the simultaneous determination of BCR-ABL and Bruton TKI concentrations in DBS was developed and validated. Owing to the small clinical sample size, further clinical validation is needed to determine the predictive performance of EPCs for the 6 TKIs.

Volumetric dried blood microsampling for monitoring imatinib mesylate therapy: Method development and clinical application in patients with chronic myeloid leukemia

Chronic Myeloid Leukemia (CML) is a hematologic neoplasia, characterized as a proliferative disease of the hematopoietic system. Imatinib mesylate (IM), a selective tyrosine kinase inhibitor, is considered a first-line therapy for CML, indicated for both adult and pediatric patients presenting the Philadelphia chromosome (Ph+). However, patients in treatment with IM may show different responses due to interindividual pharmacokinetic variability. Therapeutic drug monitoring should be routinely performed to identify treatment response profile, adherence to treatment, or possible drug interactions, thus supporting better treatment management. Volumetric absorptive microsampling (VAMS) are innovative devices for blood collection whose advantages include the possibility of home collection by the patient or at the physician's office. The assay was fully validated according to bioanalytical validation guidelines. Estimated plasma concentrations of IM were not statistically different between groups according to adherence (p = 0.15), with median of 789 ng ml-1 in the group with some level of non-adherence versus 1141.9 ng ml-1 in the group with adherence, classified with the Morisky-Green questionnaire. This study included 33 patients with CML in treatment with IM. These patients answered socioeconomic, sociodemographic, and adherence profile (Morisky-Green) questionnaires. Patients also received instructions for home blood collection with VAMS devices. Afterwards, the samples were analyzed by LC-MS/MS. The mean age of the patients was 52 years, 84.8% were ingesting doses of 400 mg/day and the majority were male (69.7%). IM and its metabolite NIM were extracted from VAMS with an aqueous solution with 0.1% formic acid, followed by protein precipitation with acetonitrile. The methodology developed in this study was satisfactory for the determination of IM and NIM in VAMS and can be used in hospital and office routines for the therapeutic monitoring of patients with CML.

Pyrazinamide-induced Polyarthralgia and Myalgia in a Case of Stable Chronic Kidney Disease

Abstract: Pyrazinamide is known to cause hyperuricemia and is followed by gout arthritis. But the fate of this drug in chronic kidney disease (CKD) patients is still not explored in details yet. We report a case of a 65-year-old Asian-Indian woman who was diagnosed with stable CKD 5 years ago and is currently diagnosed with peritoneal tuberculosis with pleural effusion. She was started on antitubercular therapy (ATT). On the 11th day of ATT, she developed a rise in uric acid (from 7.2 mg/dL to 13.1 mg/dL) and creatine kinase levels (from 156 U/L to 887 U/L), followed by polyarthralgia and generalised myalgia on investigation. Her elevated uric acid and creatine kinase levels and polyarthralgia improved on cessation of pyrazinamide, but improvement in her myalgia and muscle weakness was postponed. Pyrazinamide plasma 2 hr levels post dose was performed suspecting polyarthralgia and myalgia as an adverse drug reaction and estimated to be 59 μg/ml (normal range: 20-50 μg/ml). Subjective and objective assessments along with pyrazinamide plasma levels may be an indicative evidence of the adverse reaction as the estimated plasma concentration at 2 hr was higher than the normal range. Key words: Pyrazinamide, Polyarthralgia, Myalgia, Stable chronic kidney disease, Plasma levels.

Machine Learning Prediction of the Three Main Input Parameters of a Simplified Physiologically Based Pharmacokinetic Model Subsequently Used to Generate Time-Dependent Plasma Concentration Data in Humans after Oral Doses of 212 Disparate Chemicals.

Physiologically based pharmacokinetic (PBPK) modeling has the potential to play significant roles in estimating internal chemical exposures. The three major PBPK model input parameters (i.e., absorption rate constants, volumes of the systemic circulation, and hepatic intrinsic clearances) were generated in silico for 212 chemicals using machine learning algorithms. These input parameters were calculated based on sets of between 17 and 65 chemical properties that were generated by in silico prediction tools before being processed by machine learning algorithms. The resulting simplified PBPK models were used to estimate plasma concentrations after virtual oral administrations in humans. The estimated absorption rate constants, volumes of the systemic circulation, and hepatic intrinsic clearance values for the 212 test compounds determined traditionally (i.e., based on fitting to measured concentration profiles) and newly estimated had correlation coefficients of 0.65, 0.68, and 0.77 (p < 0.01, n = 212), respectively. When human plasma concentrations were modeled using traditionally determined input parameters and again using in silico estimated input parameters, the two sets of maximum plasma concentrations (r = 0.85, p < 0.01, n = 212) and areas under the curve (r = 0.80, p < 0.01, n = 212) were correlated. Virtual chemical exposure levels in liver and kidney were also estimated using these simplified PBPK models along with human plasma levels. These results indicate that the PBPK model input parameters for humans of a diverse set of compounds can be reliability estimated using chemical descriptors calculated using in silico tools.

Development and validation of an assay for the measurement of gentamicin concentrations in dried blood spots using UHPLC-MS/MS

Gentamicin sulfate (GEN) is an aminoglycoside antibiotic with a narrow therapeutic range of plasma concentrations. The collection of venous blood represents a significant burden for patients, especially in neonatology. Dried blood spots (DBS) obtained from capillary blood can be an alternative for drug measurements in this particular population. This study aimed to develop and validate an assay for the quantification of GEN in DBS using UHPLC-MS/MS. Total GEN concentrations were obtained by adding the individual concentrations of the GEN forms C1, C1a, and C2. The assay used a DBS disk containing approximately 17 μL of blood for GEN quantitation in the range of 0.1–40 mg L-1. Measurement accuracy for total GEN was in the range of 102.6–108.6%, inter-assay precision was 11.3–13.1% and intra-assay precision was 9.1–12.8.% GEN was stable for 21 days at − 20 and 8 °C, but only for 24 h at room temperature. Blood Hct affected the accuracy within acceptable limits (93.8–95% at Hct% of 30, 104.3–113% at Hct% of 50). Blood spotted volume did not affect GEN measurement accuracy. Concentrations of GEN in DBS obtained after heel pricks were correlated to plasma levels in a small cohort of neonatal patients. However, percentual differences between estimated plasma concentrations and actual plasma levels presented values between − 64–35.3% (average difference of − 1.9%). The use of DBS for the measurement of GEN concentrations can increase access to TDM of this antibiotic due to the ease of sample collection and the facilitated specimen transportation logistics when testing is not available onsite.

Remdesivir induces persistent mitochondrial and structural damage in human induced pluripotent stem cell-derived cardiomyocytes.

AimsRemdesivir is a prodrug of an adenosine triphosphate analogue and is currently the only drug formally approved for the treatment of hospitalised COVID-19 patients. Nucleoside/nucleotide analogues have been shown to induce mitochondrial damage and cardiotoxicity, and this may be exacerbated by hypoxia, which frequently occurs in severe COVID-19 patients. Although there have been few reports of adverse cardiovascular events associated with remdesivir, clinical data are limited. Here, we investigated whether remdesivir induced cardiotoxicity using an in vitro human cardiac model.Methods and ResultsHuman induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were exposed to remdesivir under normoxic and hypoxic conditions to simulate mild and severe COVID-19 respectively. Remdesivir induced mitochondrial fragmentation, reduced redox potential and suppressed mitochondrial respiration at levels below the estimated plasma concentration under both normoxic and hypoxic conditions. Non-mitochondrial damage such as electrophysiological alterations and sarcomere disarray were also observed. Importantly, some of these changes persisted after the cessation of treatment, culminating in increased cell death. Mechanistically, we found that inhibition of DRP1, a regulator of mitochondrial fission, ameliorated the cardiotoxic effects of remdesivir, showing that remdesivir-induced cardiotoxicity was preventable and excessive mitochondrial fission might contribute to this phenotype.ConclusionsUsing an in vitro model, we demonstrated that remdesivir can induce cardiotoxicity in hiPSC-CMs at clinically relevant concentrations. These results reveal previously unknown potential side-effects of remdesivir and highlight the importance of further investigations with in vivo animal models and active clinical monitoring to prevent lasting cardiac damage to patients.Translational perspectiveAdult cardiomyocytes have limited ability to regenerate, thus treatment-induced cardiotoxicity can potentially cause irreparable harm. Remdesivir is currently the only FDA approved treatment for COVID-19 but clinical safety data are limited. Using human pluripotent stem cell-derived cardiomyocytes, we revealed that remdesivir induced persistent mitochondrial and structural abnormalities at clinically relevant concentrations. We advise confirmatory experiments in in vivo animal models, investigations of cardioprotective strategies, and closer patient monitoring such that treatment-induced cardiotoxicity does not contribute to the long term sequelae of COVID-19 patients.

Dried Blood Spot Technique Applied in Therapeutic Drug Monitoring of Anticancer Drugs: a Review on Conversion Methods to Correlate Plasma and Dried Blood Spot Concentrations

Anticancer drugs are notoriously characterized by a low therapeutic index, the introduction of therapeutic drug monitoring (TDM) in oncologic clinical practice could therefore be fundamental to improve treatment efficacy. In this context, an attractive technique to overcome the conventional venous sampling limits and simplify TDM application is represented by dried blood spot (DBS). Despite the significant progress made in bioanalysis exploiting DBS, there is still the need to tackle some challenges that limit the application of this technology: one of the main issues is the comparison of drug concentrations obtained from DBS with those obtained from reference matrix (e.g., plasma). In fact, the use of DBS assays to estimate plasma concentrations is highly dependent on the chemical-physical characteristics of the measured analyte, in particular on how these properties determine the drug partition in whole blood. In the present review, we introduce a critical investigation of the DBS-to-plasma concentration conversion methods proposed in the last ten years and applied to quantitative bioanalysis of anticancer drugs in DBS matrix. To prove the concordance between DBS and plasma concentration, the results of statistical tests applied and the presence or absence of trends or biases were also considered.

Exposure-efficacy analyses of nintedanib in patients with chronic fibrosing interstitial lung disease.

The tyrosine kinase inhibitor nintedanib reduces the rate of decline in forced vital capacity (FVC) in patients with idiopathic pulmonary fibrosis (IPF), other chronic fibrosing interstitial lung diseases (ILDs) with a progressive phenotype and systemic sclerosis-associated ILD (SSc-ILD). The recommended dose of nintedanib is 150mg twice daily (BID). Data from Phase II and III trials in IPF, SSc-ILD and progressive fibrosing ILDs other than IPF were analyzed to investigate the relationship between nintedanib plasma concentrations (exposure) and efficacy. Using data from 1403 patients with IPF treated with 50-150mg nintedanib BID in Phase II and III studies, a linear disease progression model with a maximum drug effect on the rate of decline in FVC was established. Age, height and gender were pre-specified covariates on baseline FVC. Stepwise analysis revealed no other covariates with a distinct effect on the exposure-efficacy relationship. The estimated plasma concentration producing 80% of the maximum drug effect was 10-13ng/mL, close to the median exposure at 150mg BID (10ng/mL). The model in IPF was adapted using Phase III data from 575 patients with SSc-ILD and 663 patients with progressive fibrosing ILDs other than IPF. Besides differences in the natural decline in FVC without treatment, data were consistent with the exposure-efficacy relationship in IPF. For most patients with chronic fibrosing ILDs, the 150mg nintedanib BID dose provides exposure levels associated with a therapeutic effect close to the maximum nintedanib effect independent of disease condition or baseline demographics.

IL-6 as a Mediator of the Association Between Traditional Risk Factors and Future Myocardial Infarction: A Nested Case-Control Study.

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An explorative approach to understanding individual differences in driving performance and neurocognition in long‐term benzodiazepine users

ObjectivePrevious research reported cognitive and psychomotor impairments in long‐term users of benzodiazepine receptor agonists (BZRAs). This article explores the role of acute intoxication and clinical complaints.MethodsNeurocognitive and on‐road driving performance of 19 long‐term (≥6 months) regular (≥twice weekly) BZRA users with estimated plasma concentrations, based on self‐reported use, exceeding the therapeutic threshold (CBZRA+), and 31 long‐term regular BZRA users below (CBZRA−), was compared to that of 76 controls.ResultsBZRA users performed worse on tasks of response speed, processing speed, and sustained attention. Age, but not CBZRA or self‐reported clinical complaints, was a significant covariate. Road‐tracking performance was explained by CBZRA only. The CBZRA + group exhibited increased mean standard deviation of lateral position comparable to that at blood‐alcohol concentrations of 0.5 g/L.ConclusionsFunctional impairments in long‐term BZRA users are not attributable to self‐reported clinical complaints or estimated BZRA concentrations, except for road‐tracking, which was impaired in CBZRA + users. Limitations to address are the lack of assessment of objective clinical complaints, acute task related stress, and actual BZRA plasma concentrations. In conclusion, the results confirm previous findings that demonstrate inferior performance across several psychomotor and neurocognitive domains in long‐term BZRA users.

Evaluation of dried blood spots as an alternative matrix for therapeutic drug monitoring of abiraterone and delta(4)-abiraterone in prostate cancer patients

Therapeutic drug monitoring (TDM) approaches may benefit patients treated with abiraterone acetate (AA) as drug efficacy is imprecise and important pharmacokinetic variability is known. Current methods based on the analysis of plasma present the disadvantage of the fast degradation of the analytes in the liquid sample. Dried blood spots (DBS) consist of a minimally invasive and unexplored sampling strategy to monitor the levels of abiraterone (ABI) and delta(4)-abiraterone (D4A) in patients. This study presents the development and validation of a precise and accurate method to monitor ABI and D4A in DBS samples by UPLC-MS/MS. Bioanalytical method validation was carried out according to current guidelines, evaluating the impact of DBS-specific parameters such as hematocrit and spot volume on accuracy. Based on the analysis of quality control samples prepared at low, medium and high concentrations, the method was precise with CV ≤ 6.97 % and 10.26 % for ABI and D4A, respectively. The method was also highly accurate, between 93.6–106.8 % for ABI and 96.0–108.5 % for D4A. The DBS method is compatible with the analysis of samples of unknown volume and hematocrit range of the studied population. In addition, ABI and D4A were stable for 7 days in DBS at room temperature, which is feasible for sample transportation in postal service and analysis in the laboratory. Method application to 16 clinical samples revealed good correlation between measured plasma concentrations and estimated plasma concentrations for ABI (r = 0.884, P < 0.05) and D4A (r = 0.920, P < 0.05). Passing-Bablok regression analysis and Bland-Altmann plots indicated correlation between the results obtained from DBS and plasma, with a slight overestimation of the concentrations of ABI in DBS, which could be related to the small study cohort. Therefore, the results of this first work indicate that DBS consist of a promising alternative sampling strategy in TDM studies of AA.