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Antifungal therapeutic drug monitoring (TDM) is recommended for hospitalized patients receiving itraconazole, posaconazole, or voriconazole for treatment or prophylaxis. In this analysis of hospital-based data, TDM was uncommonly performed (15.8%) in a large cohort of eligible patients, suggesting missed opportunities to avoid subtherapeutic drug levels and minimize toxicity.

Abstract In dermatologists' clinical practice, the use of systemic glucocorticoids is recurrent for the management of different comorbidities that require chronic immunosuppression. The prescription of this medication requires caution and basic clinical knowledge due to the several adverse effects inherent to the treatment. However, different doubts may arise or inappropriate conduct may be adopted due to the lack of objective and specific guidelines for the screening, prophylaxis and management of complications from chronic corticosteroid therapy. Considering this problem, the authors carried out a narrative review of the literature to gather up-to-date data on adverse effects secondary to the chronic use of systemic glucocorticoids. The broad approach to this topic made it possible to review the pathophysiology and risk factors for these complications, as well as to develop updated orientation that can be used as a learning tool and quick reference for dermatologists during their clinical practice with glucocorticoids.

Therapeutic drug monitoring of β-lactam antibiotics has become an important tool for treatment of severe infections, especially for critically ill patients who often exhibit altered PK/PD. Therapeutic targets are based on MIC, which refers to the active concentration of the drug. Cefazolin, a β-lactam agent used for treating of MSSA bacteraemia, has a protein binding of approximately 80 %. Therefore, a reliable determination of the active, non-protein-bound concentration is required to ensure optimal therapeutic outcome.

Introduction. A specialized service for antifungal blood level determination is not available in Colombia. This service is essential for the proper follow-up of antifungal therapies. Objective. To standardize and validate a simple, sensitive, and specific protocol based on high-performance liquid chromatography with a diode array detector for voriconazole blood level quantification. Materials and methods. We used an Agilent HPLC™ series-1200 equipment with a UVdiode array detector with an analytical column Eclipse XDB-C18 and pre-column Eclipse- XDB-C18 (Agilent). We used voriconazole as the primary control and posaconazole as an internal control. We performed the validation following the Food and Drug Administration (FDA) recommendations. Results. The best chromatographic conditions were: Column temperature of 25°C, UV variable wavelength detection at 256 nm for voriconazole and 261 nm for posaconazole (internal standard); 50 μl of injection volume, 0,8 ml/min volume flow, 10 minutes of run time, and mobile phase of acetonitrile:water (60:40). Finally, retention times were 3.13 for voriconazole and 5.16 minutes for posaconazole. Quantification range varied from 0.125 μg/ml to 16 μg/ml. Conclusion. The selectivity and chromatographic purity of the obtained signal, the detection limits, and the standardized quantification make this method an excellent tool for the therapeutic monitoring of patients treated with voriconazole.

Abstract Background An increasing use of newer antiseizure medication (ASM) such as SV2A ligand brivaracetam is observed. However, data on newer antiseizure medication and therapeutic drug monitoring during pregnancy is scarce. Methods Therapeutic drug monitoring of brivaracetam (BRV) and topiramate (TPM) serum levels were performed during pregnancy, delivery and in the umbilical cord blood at delivery in a 34-year-old female patient with severe drug-resistant epilepsy. Results During pregnancy, the serum levels of brivaracetam and topiramate remained stable. At 39th week of pregnancy, the patient gave birth to a healthy daughter. 1.5 h after the last ASM intake, the penetration rate measured in umbilical cord blood was 45% lower for BRV and 35% lower for TPM. Conclusions While the pharmacokinetics of topiramate are well known and its use during pregnancy should only be undertaken under special circumstances, there have been few studies on newer ASM in pregnancy such as brivaracetam. Based on our results and other case reports of BRV use during pregnancy, further studies are necessary to confirm its pharmacokinetics and safety during pregnancy.

Oral endocrine therapies (OET) for breast cancer treatment need to be taken over a long period of time and are associated with considerable side effects. Therefore, adherence to OET is an important issue and of high clinical significance for breast cancer patients' caregivers. We hypothesized that a new bioanalytical strategy based on liquid chromatography and high-resolution mass spectrometry might be suitable for unbiased adherence monitoring (AM) of OET. Four different biomatrices (plasma, urine, finger prick blood by volumetric absorptive microsampling (VAMS), oral fluid (OF)) were evaluated regarding their suitability for AM of the OET abemaciclib, anastrozole, exemestane, letrozole, palbociclib, ribociclib, tamoxifen, and endoxifen. An analytical method was developed and validated according to international recommendations. The analytical procedures were successfully validated in all sample matrices for most analytes, even meeting requirements for therapeutic drug monitoring. Chromatographic separation of analytes was achieved in less than 10 min and limits of quantification ranged from 1 to 1000 ng/mL. The analysis of 25 matching patient samples showed that AM of OET is possible using all four matrices with the exception of, e.g., letrozole and exemestane in OF. We were able to show that unbiased bioanalytical AM of OET was possible using different biomatrices with distinct restrictions. Sample collection of VAMS was difficult in most cases due to circulatory restraints and peripheral neuropathy in fingers and OF sampling was hampered by dry mouth syndrome in some cases. Although parent compounds could be detected in most of the urine samples, metabolites should be included when analyzing urine or OF. Plasma is currently the most suitable matrix due to available reference concentrations. [ABSTRACT FROM AUTHOR]

Current healthcare trends have seen an increased emphasis on the move towards personalised precision medicine to tailor treatments to the individual and their response to diseases and disease therapies. This highlighting a transition from traditional "one size fits all" to a more nuanced approach. Despite advancements in fundamental knowledge to facilitate personalised prevision approaches, lack of resources to implement such plans remains one of the largest hurdles to overcome. Monitoring of drug therapies is one key aspect that could aid in the evolution of precision medicine alongside the development of drugs and targeted treatment systems. This contribution illustrates the potential of square wave voltammetry (SWV) as a proof-of-concept for monitoring of circulating blood concentrations of treatment therapies within artificial urine, using leucovorin calcium (LV) as a model cancer therapy drug. A low cost, easy-to-use and portable sensor has been developed and successfully employed for the detection of LV over the linear range 0.5–30 μM which represents the therapeutically relevant concentrations for LV within artificial urine without any prior sample preparation required with a limit of detection of 2.63 μM and initial investigations into saliva and serum as biological matrices. The developed sensor describe herein exhibits a proof-of-concept for the engagement of such electrochemical sensors as point-of-care devices, where the sensors ease of use and removal of time-consuming and complex sample preparation methods will ultimately increase its usability by physicians, widening the avenues where electrochemical sensors could be employed. [ABSTRACT FROM AUTHOR]

Background When performing therapeutic drug monitoring (TDM) for flucloxacillin, it is advised to measure the unbound, not the total, flucloxacillin concentration. To be able to accurately quantify unbound flucloxacillin concentrations, a reliable analytical method is indispensable. Objective To determine the influence of temperature and pH of the sample during ultrafiltration on the measured unbound fraction of flucloxacillin. Materials and methods We performed three different experiments. In a single laboratory experiment, we investigated the influence of ultrafiltration temperature (10°C, room temperature and 37°C) on the measured unbound fraction of flucloxacillin for three concentration levels. In a multiple laboratory experiment, the results of eight laboratories participating in an international quality control programme measuring unbound flucloxacillin concentrations were analysed. In the third experiment, patient samples were ultrafiltrated using four different conditions: (i) physiological pH and room temperature; (ii) unadjusted pH (pH 9 after freezing) and room temperature; (iii) physiological pH and 37°C and (iv) unadjusted pH and 37°C. Results For all experiments, measurement of samples that were ultrafiltrated at room temperature resulted in a substantially lower unbound fraction compared to samples that were ultrafiltrated at 37°C. Adjusting the pH to physiological pH only had a minimal impact on the measured unbound fraction. Conclusions On the basis of these findings and considering the need for fast, simple and reproducible sample pretreatment for TDM purposes, we conclude that ultrafiltration of flucloxacillin should be performed at physiological temperature (37°C), but adjustment of pH does not seem to be necessary. [ABSTRACT FROM AUTHOR]

The establishment of a convenient and effective detection method for doxycycline (DC) holds significant importance in drug monitoring and drug residue assessment. In this work, carbon quantum dots (CQDs) with excellent and stable luminescence performance (the quantum yield of CQDs was 21.8%) were synthesized by the melting method and employed as probes to monitor the fluorescence intensity variations before and after the introduction of DC. A fluorescence analytical method based on the internal filtration effect (IFE) was developed for DC determination. The mechanism of DC quenching CQDs was verified using fluorescence lifetime tests, absorption spectroscopy, and evaluation of internal filtration parameters. After optimizing experimental conditions, it was found that the DC concentration (CDC) exhibited a good linear relationship with the fluorescence quenching efficiency ((F0-F)/F0) of CQDs in the range of 5–30 µM. The fitted linear equation was Y = 0.01249*CDC+0.03625, R2 = 0.9987, and the detection limit was 2.343 µM (n = 8). This developed method has been successfully applied to accurately determine DC concentrations in both doxycycline hydrochloride tablets and human serum samples. It stands out for its simplicity, rapidity, and acceptable detection performance. Due to its advantages, this method holds great promise for application in the biomedical field for monitoring DC drug concentrations and ensuring quality control. [ABSTRACT FROM AUTHOR]

Aims: Eculizumab is a monoclonal antibody targeting complement protein C5 used in renal diseases. As recommended dosing regimen leads to unnecessarily high concentrations in some patients, tailored dosing therapeutic drug monitoring was proposed to reduce treatment cost. The objectives of the present work were (i) to investigate the target‐mediated elimination of eculizumab and (ii) whether a pharmacokinetic model integrating a nonlinear elimination allows a better prediction of eculizumab concentrations than a linear model. Methods: We analysed 377 eculizumab serum concentrations from 44 patients treated for atypical haemolytic uraemic syndrome and C3 glomerulopathy with a population pharmacokinetic approach. Critical concentrations (below which a non‐log‐linear decline of concentration over time is evidenced) were computed to estimate the relevance of the target‐mediated elimination. Simulations of dosing regimens were then performed to predict probabilities of target attainment (i.e. trough >100 mg/L). Results: Pharmacokinetics of eculizumab was nonlinear and followed a mixture of first‐order (CL = 1.318 mL/day/kg) and Michaelis–Menten elimination (Vmax = 26.07 mg/day, Km = 24.06 mg/L). Volume of distribution (72.39 mL/kg) and clearance were weight‐dependent. Critical concentrations (Vmax/CL) ranged from 144.7 to 759.7 mg/L and were inversely related to body weight (P =.013). Nonlinearity was thus noticeable at therapeutic concentrations. Simulations predicted that 1200 mg of eculizumab every 21 days would allow 85% and 76% of patients to maintain a therapeutic exposure, for 50 or 90 kg body weight, respectively. Conclusions: Our study investigates the nonlinear elimination of eculizumab and discusses the importance of accounting for eculizumab target‐mediated elimination in therapeutic drug monitoring. [ABSTRACT FROM AUTHOR]

Aims: Monitoring drug safety in real‐world settings is the primary aim of pharmacovigilance. Frequent adverse drug reactions (ADRs) are usually identified during drug development. Rare ones are mostly characterized through post‐marketing scrutiny, increasingly with the use of data mining and disproportionality approaches, which lead to new drug safety signals. Nonetheless, waves of excessive numbers of reports, often stirred up by social media, may overwhelm and distort this process, as observed recently with levothyroxine or COVID‐19 vaccines. As human resources become rarer in the field of pharmacovigilance, we aimed to evaluate the performance of an unsupervised co‐clustering method to help the monitoring of drug safety. Methods: A dynamic latent block model (dLBM), based on a time‐dependent co‐clustering generative method, was used to summarize all regional ADR reports (n = 45 269) issued between 1 January 2012 and 28 February 2022. After analysis of their intra and extra interrelationships, all reports were grouped into different cluster types (time, drug, ADR). Results: Our model clustered all reports in 10 time, 10 ADR and 9 drug collections. Based on such clustering, three prominent societal problems were detected, subsequent to public health concerns about drug safety, including a prominent media hype about the perceived safety of COVID‐19 vaccines. The dLBM also highlighted some specific drug–ADR relationships, such as the association between antiplatelets, anticoagulants and bleeding. Conclusions: Co‐clustering and dLBM appear as promising tools to explore large pharmacovigilance databases. They allow, 'unsupervisedly', the detection, exploration and strengthening of safety signals, facilitating the analysis of massive upsurges of reports. [ABSTRACT FROM AUTHOR]

Aims: Although therapeutic drug monitoring (TDM) of voriconazole is performed in outpatients to prevent treatment failure and toxicity, whether TDM should be performed in all or only selected patients remains controversial. This study evaluated the association between voriconazole trough concentrations and clinical events. Methods: We investigated the aggravation of clinical symptoms, incidence of hepatotoxicity and visual disturbances, change in co‐medications and interaction between voriconazole and co‐medications in outpatients receiving voriconazole between 2017 and 2021 in three facilities. Abnormal trough concentrations were defined as <1.0 mg/L (low group) and >4.0 mg/L (high group). Results: A total of 141 outpatients (578 concentration measurements) met the inclusion criteria (treatment, 37 patients, 131 values; prophylaxis, 104 patients, 447 values). The percentages of patients with abnormal concentrations were 29.0% and 31.5% in the treatment and prophylaxis groups, respectively. Abnormal concentrations showed 50% of the concentrations at the first measurement in both therapies. Aggravation of clinical symptoms was most frequently observed in the low treatment group (18.2%). Adverse events were most common in the high group for both therapies (treatment, hepatotoxicity 6.3%, visual disturbance 18.8%; prophylaxis, hepatotoxicity 27.9%). No differences were found in changes to co‐medications and drug interactions. In the prophylaxis group, prescription duration in the presence of clinical events tended to be longer than in their absence (47.4 ± 23.4 days vs 39.7 ± 21.9 days, P =.1132). Conclusions: We developed an algorithm based on clinical events for appropriate implementation of TDM in outpatients. However, future interventions based on this algorithm should be validated. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to develop a population pharmacokinetic model for methotrexate (MTX) during high-dose treatment (HDMTX) in pediatric patients with acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL) and to describe the influence of variability factors. Methods: The study included 50 patients of both sexes (aged 1–18 years) who received 3 or 5 g/m2 of HDMTX. A nonlinear mixed effect modeling approach was applied for data analysis. Parameter estimation was performed by first-order conditional estimation method with interaction (FOCEI), whereas stepwise covariate modeling was used to assess variability factors. Results: The final model is a two-compartment model that incorporates the effect of body surface area and the influence of hemoglobin and serum creatinine on MTX clearance (CL). Population pharmacokinetic values for a typical subject were estimated at 5.75 L/h/m2 for clearance (CL), 21.3 L/m2 for volume of the central compartment (V1), 8.2 L/m2 for volume of the peripheral compartment (V2), and 0.087 L/h/m2 for intercompartmental clearance (Q). According to the final model, MTX CL decreases with increasing serum creatinine, whereas a positive effect was captured for hemoglobin. A difference of almost 32% in MTX CL was observed among patients' hemoglobin values reported in the study. Conclusion: The developed population pharmacokinetic model can contribute to the therapy optimization during HDMTX in pediatric patients with ALL and NHL. In addition to renal function and body weight, it describes the influence of hemoglobin on CL, allowing better understanding of its contribution to the disposition of HDMTX. [ABSTRACT FROM AUTHOR]

Background: Augmented renal clearance (ARC) holds a risk of subtherapeutic drug concentrations. Knowledge of patient-, disease-, and therapy-related factors associated with ARC would allow predicting which patients would benefit from intensified dosing regimens. This study aimed to identify ARC predictors and to describe ARC time-course in critically ill children, using iohexol plasma clearance (CLiohexol) to measure glomerular filtration rate (GFR). Methods: This is a retrospective analysis of data from the "IOHEXOL" study which validated GFR estimating formulas (eGFR) against CLiohexol. Critically ill children with normal serum creatinine were included, and CLiohexol was performed as soon as possible after pediatric intensive care unit (PICU) admission (CLiohexol1) and repeated (CLiohexol2) after 48–72 h whenever possible. ARC was defined as CLiohexol exceeding normal GFR for age plus two standard deviations. Results: Eighty-five patients were included; 57% were postoperative patients. Median CLiohexol1 was 122 mL/min/1.73 m2 (IQR 75–152). Forty patients (47%) expressed ARC on CLiohexol1. Major surgery other than cardiac surgery and eGFR were found as independent predictors of ARC. An eGFR cut-off value of 99 mL/min/1.73 m2 and 140 mL/min/1.73 m2 was suggested to identify ARC in children under and above 2 years, respectively. ARC showed a tendency to persist on CLiohexol2. Conclusions: Our findings raise PICU clinician awareness about increased risk for ARC after major surgery and in patients with eGFR above age-specific thresholds. This knowledge enables identification of patients with an ARC risk profile who would potentially benefit from a dose increase at initiation of treatment to avoid underexposure. Trial registration: ClinicalTrials.gov NCT05179564, registered retrospectively on January 5, 2022. [ABSTRACT FROM AUTHOR]

Background: As one of the most famous natural products, salvianolic acid A (SAA) is undergoing clinical trials for the treatments of angina pectoris and coronary heart disorders. However, the in vivo metabolites of SAA have only been tentatively identified, leading to a barrier for precise therapeutical drug monitoring. Methods: Ultra-high performance liquid chromatography coupled with quadrupole time of flight tandem mass spectrometry (UPLC–Qtof-MS/MS) was firstly employed to acquire high-resolution MS1 and MS2 spectra for all metabolites. Through paying special attention onto the features of ester bond dissociation, metabolism sites were restricted at certain regions. To further determine the metabolism site, such as the monomethylated products (M23, M25, and M26), post collision-induced dissociation energy-resolved mass spectrometry (post-CID ER-MS) was proposed through programming progressive exciting energies to the second collision chamber of hybrid triple quadrupole-linear ion trap mass spectrometry (Qtrap-MS) device. Results: After SAA oral administration, 29 metabolites (M1–M29), including five, thirteen, and sixteen ones in rat plasma, urine, and feces, respectively, were detected in rats. The metabolism route was initially determined by applying well-defined mass fragmentation pathways to those HR-m/z values of precursor and fragment ions. Metabolism site was limited to SAF- or DSS-unit based on the fragmentation patterns of ester functional group. Through matching the dissociation trajectories of concerned 1st-generation fragment ions with expected decomposition product anions using post-CID ER-MS strategy, M23 and M25 were unequivocally assigned as 3'-methyl-SAA and 3''-methyl-SAA, and M26 was identified as 2-methyl-SAA or 3-methyl-SAA. Hydrolysis, methylation, glucuronidation, sulfation, and oxidation were the primary metabolism channels being responsible for the metabolites' generation. Conclusion: Together, the metabolism regions and sites of SAA metabolites were sequentially identified based on the ester bond dissociation features and post-CID ER-MS strategy. Importantly, the present study provided a promising way to elevate the structural identification confidence of natural products and metabolites. [ABSTRACT FROM AUTHOR]

There is great interindividual difference in the plasma concentration of quetiapine, and optimizing quetiapine therapy to achieve a balance between efficacy and safety is still a challenge. In our study, a population pharmacokinetic (PPK) model considering genetic information was developed with the expectation of comprehensively explaining this observation in Chinese patients with bipolar disorder. Patients who were dispensed quetiapine and underwent the therapeutic drug monitoring (TDM) were included. The genotypes of CYP3A5*3 , CYP2D6*10 , and ABCB1 C3435T/G2677T were analyzed. Finally, a multivariable linear regression model was applied to describe the PPK of quetiapine considering the covariates weight, height and genotype information. A total of 175 TDM points from 107 patients were adopted for PPK model development. Resultantly, the CL/F of quetiapine in CYP3A5 expressers was 81.1 CL/h, whereas it was 43.6 CL/h in CYP3A5 nonexpressers. The interindividual variability in CL/F was 47.7 %. However, neither the ABCB1 nor CYP2D6 genotype was significantly associated with the predictor of quetiapine clearance in our study. Only trough concentrations were collected, and the span between different points was relatively wide, impeding the application of the typical nonlinear compartment model for PPK analysis. In addition, this was a single-center study which limited the sample of wild-type CYP3A5 carriers. The currently established PPK model of quetiapine considering the contribution of the CYP3A5 genotype could efficiently predict the population and individual pharmacokinetic parameters of Chinese bipolar disorder patients, which could better guide the personalized therapy with quetiapine, thus to achieve the best clinical response. [ABSTRACT FROM AUTHOR]

Nirmatrelvir/ritonavir is a promising option for preventing severe COVID-19 in solid organ transplant recipients with SARS-CoV-2 infection. However, concerns have arisen regarding potential drug interactions with calcineurin inhibitors (CNI). This two-phase multicentre retrospective study, involving 113 patients on tacrolimus and 13 on cyclosporine A, aimed to assess the feasibility and outcomes of recommendations issued by The French societies of transplantation (SFT) and pharmacology (SFPT) for CNI management in this context. The study first evaluated adherence to recommendations, CNI exposure, and clinical outcomes. Notably, 96.5% of patients on tacrolimus adhered to the recommendations, maintaining stable tacrolimus trough concentrations (C0) during nirmatrelvir/ritonavir treatment. After reintroduction, most patients experienced increased C0, with 42.9% surpassing 15 ng/mL, including three patients exceeding 40 ng/mL. Similar trends were observed in cyclosporine A patients, with no COVID-19-related hospitalizations. Moreover, data from 22 patients were used to refine the reintroduction strategy. Modelling analyses suggested reintroducing tacrolimus at 50% of the initial dose on day 8, and then at 100% from day 9 as the optimal approach. In conclusion, the current strategy effectively maintains consistent tacrolimus exposure during nirmatrelvir/ritonavir treatment, and a stepwise reintroduction of tacrolimus may be better suited to the low CYP3A recovery. [ABSTRACT FROM AUTHOR]

Objective Methods Results Conclusions Therapeutic drug monitoring is used clinically to guide anti‐tumor necrosis factor (TNF) therapy for inflammatory bowel disease (IBD), but its use for ustekinumab (UST) remains unclear. This study aimed to determine predictive variables of UST levels.In this retrospective cohort of patients with IBD, UST trough levels were drawn at maintenance dosing. Relationships between UST trough levels and demographics, therapy, and outcomes were analyzed. Machine‐learning models were used to infer combinatorial traits predictive of UST levels.Altogether 177 patients with IBD on UST had a mean UST trough level of 4.742 μg/mL. The injection schedule correlated significantly (P < 0.001) with UST levels. Naiveté to anti‐TNFs correlated with higher UST levels (P = 0.048). Univariate analysis revealed that higher inflammatory biomarkers significantly correlated to lower UST levels and a lower Simple Endoscopic Score to Crohn's Disease to adequate UST levels (P = 0.018). Multivariate analysis identified body mass index (BMI), previous anti‐TNF failure, and laboratory flare as predictors of UST levels with an area under the receiver operating characteristic curve (AUROC) of 0.72. The UST cut‐off level of 5.77 μg/mL yielded a 0.79 AUROC, 80% sensitivity, and 81% specificity for predicting endoscopic remission of Crohn's disease. For the clinical remission end‐point in ulcerative colitis, UST level of 4.73 μg/mL yielded a 0.69 AUROC, 53% sensitivity, and 86% specificity.Higher UST levels correlated with less disease activity. BMI was an important consideration for UST response as well. Therefore, UST dose adjustments to reach target levels may optimize response. [ABSTRACT FROM AUTHOR]

Therapeutic drug monitoring is an important clinical testing of the drugs to monitor their concentrations in plasma in order to guarantee their optimal impact, and to avoid any side effects resulting from drug-drug interactions. A green reversed-phase high-performance liquid chromatographic method using a photodiode array detector (RP-HPLC-PDA) was developed for the simultaneous determination of three carbapenem antibiotics (Imipenem, ertapenem, and meropenem) with the co-formulated drug (cilastatin) and contraindicated drugs (probenecid and warfarin) in spiked human plasma. The separation was achieved at 25 °C using a gradient elution of a mixture of mobile phase A: methanol and mobile phase B: phosphate buffer (pH 3.0). The photodiode array detector was adjusted at 220 nm. Bioanalytical method validation was carried out as per the FDA guidelines, and the method showed good linearity ranges for the six drugs that included their Cmax levels along with low limits of quantification. Based on the results, the method was found to be accurate and precise; with high % recovery and good % RSD, respectively. The method was successfully applied to spiked human plasma, signifying a good potential to be implemented in future TDM studies of these drugs when co-administered together. [ABSTRACT FROM AUTHOR]

Introduction 5-fluorouracil (5-FU) is a crucial agent in treating various types of cancer, particularly recurrent head and neck cancers (HNCs). According to prior studies, individuals who underwent therapeutic drug monitoring (TDM) based 5-FU dosage adjustments showed significantly higher response rates and experienced fewer adverse events compared with those who received the standard 5-FU administration. This study aims to enhance our understanding of the overall clinical outcomes in patients with recurrent HNCs who received 500 mg of 5-FU through a pharmacokinetic (PK) analysis. Objectives Our objectives are to conduct TDM in selected HNC patients and observe individual PK responses, efficacy, tolerability, and drug toxicity. Materials and Methods We enrolled a total of 12 patients with recurrent metastatic HNC, and all of them received a fixed dose of 500 mg with cisplatin in a 21-day cycle. During cycle II or III, we analyzed the blood concentrations and PK parameters of 5-FU using the liquid chromatography and mass spectrometry (LC–MS) technique. Notably, we calculated the Concentration maximum (C max), time at which the concentration reaches maxiumum (T max), Half life of the drug (T 1/2), and area under the curve (AUC) for the 500-mg dose of 5-FU, as the PK data for this particular dose were unavailable, making our study uniquely valuable for assessing efficacy and toxicity. Results Within the study group, 83.33% obtained an average AUC range of 1,000 to 3,000 h/µg/mL. Out of this group, 41.66% showed a partial response, 33.33% experienced disease progression, and 25% remained stable during the therapy. One patient had an AUC below the expected value (832.21 h/µg/mL), while another had an overexposed AUC value (5726.87 h/µg/mL), resulting in a poor clinical outcome. After interpreting the results, suggestions for dosage adjustments were made to the clinician. Conclusion From our interventional study, it is evident that at a flat dose of 500 mg, PK-based individual dosage regimens play a superior role in managing advanced cancer patients with minimal toxicities. This PK analysis showed us clarity on the outcomes of 5-FU at a 500-mg dose. [ABSTRACT FROM AUTHOR]

Background and Objective: Efficacy of infliximab in children with inflammatory bowel disease can be enhanced when serum concentrations are measured and further dosing is adjusted to achieve and maintain a target concentration. Use of a population pharmacokinetic model may help to predict an individual's infliximab dose requirement. The aim of this study was to evaluate the predictive performance of available infliximab population pharmacokinetic models in an independent cohort of Dutch children with inflammatory bowel disease. Methods: In this retrospective study, we used data of 70 children with inflammatory bowel disease (443 infliximab concentrations) to evaluate eight models that focused on infliximab pharmacokinetic models in individuals with inflammatory bowel disease, preferably aged ≤ 18 years. Predictive performance was evaluated with prior predictions (based solely on patient-specific covariates) and posterior predictions (based on covariates and infliximab trough concentrations). Model accuracy and precision were calculated with relative bias and relative root mean square error and we determined the classification accuracy at the trough concentration target of ≥ 5 mg/L. Results: The population pharmacokinetic model by Fasanmade was identified to be most appropriate for the total dataset (relative bias before/after therapeutic drug monitoring: −20.7%/11.2% and relative root mean square error before/after therapeutic drug monitoring: 84.1%/51.6%), although differences between models were small and several were deemed suitable for clinical use. For the Fasanmade model, sensitivity and specificity for maximum posterior predictions for the next infliximab trough concentration to be ≥ 5 mg/L were respectively 83.5% and 80% with an area under the receiver operating characteristic curve of 0.870. Conclusions: In our paediatric cohort, various models provided acceptable predictive performance, with the Fasanmade model deemed most suitable for clinical use. Model-informed precision dosing can therefore be expected to help to maintain infliximab trough concentrations in the target range. [ABSTRACT FROM AUTHOR]

In patients with normal renal function, significant teicoplanin dose adjustments are often necessary. This study aimed to develop a population pharmacokinetic (PK) model for teicoplanin in healthy adults and use it to recommend optimal dosage regimens for patients with normal renal function. PK samples were obtained from 12 subjects and analyzed using a population approach. The derived parameters informed Monte Carlo simulations for dosing recommendations. The PK profile was best described using a three-compartment model, in which the estimated glomerular filtration rate calculated via the CKD-EPI equation and adjusted for body surface area was identified as a significant covariate affecting total clearance. For pathogens with a minimum inhibitory concentration of 1 mg/L, a loading dose (LD) of 14 mg/kg administered every 12 h for four doses, followed by a maintenance dose (MD) of 16 mg/kg administered every 24 h, is recommended. These findings indicate the need for dosage adjustments, such as increasing the LD and MD or decreasing the dosing interval of MD in patients with normal renal function. Because of the long half-life of teicoplanin and the requirement for long-term administration, therapeutic drug monitoring at strategic intervals is important to avoid nephrotoxicity associated with elevated trough concentrations. [ABSTRACT FROM AUTHOR]

Monitoring plasma concentrations of β-lactam antibiotics is crucial, particularly in critically ill patients, where variations in concentrations can lead to treatment failure or adverse events. Standardized antimicrobial regimens may not be effective for all patients, especially in special groups with altered physiological parameters. Pharmacokinetic/pharmacodynamic (PK/PD) studies highlight the time-dependent antibacterial activity of these antibiotics, emphasizing the need for personalized dosing. Therapeutic drug monitoring (TDM) is essential, requiring rapid and accurate analytical methods for precise determination of drugs in biological material (typically plasma or serum). This study presents a novel capillary zone electrophoresis–tandem mass spectrometry (CZE-MS/MS) method designed for the simultaneous quantification of five penicillin antibiotics, two cephalosporins, one carbapenem, and two β-lactamase inhibitors in a single run. The method involves a simple sample pretreatment—precipitation with organic solvent—and has a run time of 20 min. Optimization of CZE separation conditions revealed that 20 mM ammonium hydrogen carbonate (NH4HCO3) serves as the optimal background electrolyte (BGE). Positive electrospray ionization (ESI) mode, with isopropyl alcohol (IP)/10 mM ammonium formate water solution (50/50, v/v) as the sheath liquid, was identified as the optimal condition for MS detection. Method validation according to the Food and Drug Administration (FDA) guideline for development of bioanalytical methods demonstrated satisfactory selectivity, linearity, recovery, robustness, and stability. The method's practicality was evaluated using the Blue Applicability Grade Index (BAGI), yielding a score of 77.5. Moreover, the greenness of the proposed method was evaluated by two commonly used metric tools—Analytical GREEnness (AGREE) and Green Analytical Procedure Index (GAPI). The developed CZE-MS/MS method offers a practical and reliable approach for quantifying a broad spectrum of β-lactam antibiotics in plasma. Its ability to simultaneously quantify multiple analytes in a single run, coupled with a straightforward sample pretreatment, positions it as a valuable and prospective tool for TDM in critically ill patients. [ABSTRACT FROM AUTHOR]

An ultra-performance liquid chromatography with photodiode array (UPLC-PDA) UV detection method was developed here for the first time for simple, rapid, selective and sensitive quantification of the commonly prescribed selective cyclooxygenase-2 (COX-2) inhibitor etoricoxib in low plasma volumes (50 μL). The method includes protein precipitation followed by liquid–liquid extraction, evaporation and reconstitution. A gradient mobile phase of 75:25 going to 55:45 (v/v) water:acetonitrile (1 mL/min flow rate) was applied. Total run time was 8 min, representing a significant improvement relative to previous reports. Excellent linearity (r2 = 1) was obtained over a wide (0.1–12 µg/mL) etoricoxib concentration range. Short retention times for etoricoxib (4.9 min) and the internal standard trazodone (6.4 min), as well as high stability, recovery, accuracy, precision and reproducibility, and low etoricoxib LOD (20 ng/mL) and LOQ (100 ng/mL), were achieved. Finally, the method was successfully applied to a pharmacokinetic study (single 20 mg/kg orally administered etoricoxib mini-capsule) in rats. In conclusion, the advantages demonstrated in this work make this analytical method both time- and cost-efficient for drug monitoring in pre-clinical/clinical settings. [ABSTRACT FROM AUTHOR]

Midazolam, a short-acting benzodiazepine, is widely used to alleviate patient anxiety, enhance compliance, and aid in anesthesia. While its side effects are typically dose-dependent and manageable with vigilant perioperative monitoring, serious cardiorespiratory complications, including fatalities and permanent neurological impairment, have been documented. Prolonged exposure to benzodiazepines, such as midazolam, has been associated with neurological changes in infants. Despite attempts to employ therapeutic drug monitoring for optimal sedation dosing, its efficacy has been limited. Consequently, efforts are underway to identify alternative predictive markers to guide individualized dosing and mitigate adverse effects. Understanding these factors is crucial for determining midazolam's suitability for future administration, particularly after a severe adverse reaction. This article aims to elucidate the factors influencing midazolam's pharmacokinetics and pharmacodynamics, potentially leading to adverse events. Finally, a case study is presented to exemplify the complex investigation into the causative factors of midazolam-related adverse events. [ABSTRACT FROM AUTHOR]

Background: The antiepileptic drug lamotrigine (LTG) shows high pharmacokinetic variability due to genotype influence and concomitant use of glucuronidation inducers and inhibitors, both of which may be frequently taken by elderly patients. Our goal was to develop a reliable quantification method for lamotrigine and its main glucuronide metabolite lamotrigine-N2-glucuronide (LTG-N2-GLU) in dried blood spots (DBS) to enable routine therapeutic drug monitoring and to identify altered metabolic activity for early detection of drug interactions possibly leading to suboptimal drug response. Results: The analytical method was validated in terms of selectivity, accuracy, precision, matrix effects, haematocrit, blood spot volume influence, and stability. It was applied to a clinical study, and the DBS results were compared to the concentrations determined in plasma samples. A good correlation was established for both analytes in DBS and plasma samples, taking into account the haematocrit and blood cell-to-plasma partition coefficients. It was demonstrated that the method is suitable for the determination of the metabolite-to-parent ratio to reveal the metabolic status of individual patients. Conclusions: The clinical validation performed confirmed that the DBS technique is a reliable alternative for plasma lamotrigine and its glucuronide determination. [ABSTRACT FROM AUTHOR]

Introduction: The optimal dosing and monitoring of vancomycin in pediatrics is still unknown but has evolved to emphasize area under the curve over 24 h (AUC0–24) over minimum concentration (Cmin) monitoring. Real‐world data supporting the feasibility of two‐concentration kinetics with first‐order equations for the estimation of vancomycin AUC0–24 in pediatric patients are lacking. Objectives: To describe the interplay of vancomycin dose, AUC0–24, and Cmin using first‐order equations within four pediatric age groups. Methods: This is a single‐center, retrospective cohort study analyzing pediatric patients (<18 years) receiving intravenous vancomycin between 2020 and 2022. Included patients received at least 24 h of intravenous vancomycin with two concentrations obtained within 96 h of therapy initiation. Patients with baseline renal dysfunction were excluded. Patients were divided into four age categories: neonates (≤28 days), infants (29 days to <1 year), children (1–12 years), and adolescents (13–17 years). First‐order equations were utilized to estimate pharmacokinetic parameters and AUC0–24. Results: Overall, 219 patients (median age of 6 years [IQR 1–12]) met inclusion criteria. The median vancomycin daily dose was 30 mg/kg in neonates, 70 mg/kg in infants and children, and 52 mg/kg in adolescents. Median Cmin and AUC0–24 values among all age groups were 8.68 mg/L and 505 mg * h/L, respectively. For AUC0–24 values outside of the therapeutic range (400–600 mg * h/L), more values were SUPRAtherapeutic (>600 mg * h/L) than SUBtherapeutic (<400 mg * h/L). The overall trend within our data showed suboptimal correlation between Cmin and AUC0–24. However, 71% of patients with Cmin values of 5–10 mg/L had an AUC0–24 within the therapeutic range of 400–600 mg * h/L, whereas 23 patients (92%) with a SUPRAtherapeutic AUC0–24 had a Cmin value ≥15 mg/L. Approximately 10% of patients experienced acute kidney injury. Conclusions: Our data describe the relationship between vancomycin dose, Cmin, and AUC0–24 in pediatric patients. We demonstrated the feasibility of using first‐order equations to estimate AUC0–24, using two concentrations obtained at steady state to monitor efficacy and safety in pediatric patients receiving intravenous vancomycin. Our data showed suboptimal correlation between AUC0–24 and Cmin, which indicates that Cmin should not be used as a surrogate marker for a therapeutic AUC0–24 in pediatric patients. In alignment with the 2020 vancomycin consensus guidelines, we suggest utilizing AUC0–24 for efficacy and safety monitoring. [ABSTRACT FROM AUTHOR]

Background: Patients with Crohn's disease (CD) who lose response to biologics experience reduced quality of life (QoL) and costly hospitalizations. Precision‐guided dosing (PGD) provides a comprehensive pharmacokinetic (PK) profile that allows for biologic dosing to be personalized. We analyzed the cost‐effectiveness of infliximab (IFX) PGD relative to two other dose intensification strategies (DIS). Methods: We developed a hybrid (Markov and decision tree) model of patients with CD who had a clinical response to IFX induction. The analysis had a US payer perspective, a base case time horizon of 5 years, and a 4‐week cycle length. There were three IFX dosing comparators: PGD; dose intensification based on symptoms, inflammatory markers, and trough IFX concentration (DIS1); and dose intensification based on symptoms alone (DIS2). Patients that failed IFX initiated ustekinumab, followed by vedolizumab, and conventional therapy. Transition probabilities for IFX were estimated from real‐world clinical PK data and interventional clinical trial patient‐level data. All other transition probabilities were derived from published randomized clinical trials and cost‐effectiveness analyses. Utility values were sourced from previous health technology assessments. Direct costs included biologic acquisition and infusion, surgeries and procedures, conventional therapy, and lab testing. The primary outcomes were incremental cost‐effectiveness ratios (ICERs). The robustness of results was assessed via one‐way sensitivity, scenario, and probabilistic sensitivity analyses (PSA). Results: PGD was the cost‐effective IFX dosing strategy with an ICER of 122,932 $ per quality‐adjusted life year (QALY) relative to DIS1 and dominating DIS2. PGD had the lowest percentage (1.1%) of patients requiring a new biologic through 5 years (8.9% and 74.4% for DIS1 and DIS2, respectively). One‐way sensitivity analysis demonstrated that the cost‐effectiveness of PGD was most sensitive to the time between IFX doses. PSA demonstrated that joint parameter uncertainty had moderate impact on some results. Conclusions: PGD provides clinical and QoL benefits by maintaining remission and avoiding IFX failure; it is the most cost‐effective under conservative assumptions. [ABSTRACT FROM AUTHOR]

Amidst the US overdose epidemic, policymakers, law enforcement agencies, and healthcare institutions have contributed to a decrease in opioid prescribing, assuming reduced mortality would result—an assumption we now understand was oversimplified. At this intersection between public health and public safety domains as they relate to opioid prescribing, unregulated and proprietary clinical decision support tools have emerged without rigorous external validation or public data sharing. In the following piece, we discuss challenges facing clinicians practicing medicine amidst unregulated clinical decision support tools, using the case of Bamboo Health's NarxCare—a prescription drug monitoring program–based analytics platform marketed as a clinical decision support tool—that is already positioned to impact over 1 billion patient encounters annually. We argue that sufficient evidence does not yet exist to support NarxCare's wide implementation, and that clinical decision support tools like NarxCare have flourished in recent years due to a lack of federal regulatory oversight and shielding by their proprietary formulas, which have facilitated their unchecked and outsized influence on patient care. Finally, we suggest specific actions by federal regulatory agencies, healthcare institutions, individual clinicians, and researchers, as well as academic journals, to mitigate potential harms associated with unregulated clinical decision support tools. [ABSTRACT FROM AUTHOR]

Medication adherence is crucial for optimal treatment outcomes, yet many patients struggle to follow their prescribed regimens, impacting patients, families, and healthcare systems. Measurement of adherence is vital for effective care planning and intervention. This review explores medication adherence challenges and measurement methods, including therapeutic drug monitoring (TDM), medication event monitoring system (MEMS), analysis of adherence in insurance/pharmacy database, pill counts, and self-reports, each with its advantages and limitations. This review advocates a partnership-based approach to adherence, stressing standardized reporting and team-based care. Adherence is influenced by many factors such as complex regimens, packaging, patient perspectives, side effects. Effectively addressing these factors is crucial for improving patient outcomes. In summary, medication adherence is vital but complex. The article covers various adherence measurement methods to promote medication adherence as an important matter. [ABSTRACT FROM AUTHOR]

Rationale: Little is known about the prescribing of medications with potential to cause QTc‐prolongation in the ambulatory care settings. Understanding real‐world prescribing of QTc‐prolonging medications and actions taken to mitigate this risk will help guide strategies to optimize safety and appropriate prescribing among ambulatory patients. Objective: To evaluate the frequency of clinician action taken to monitor and mitigate modifiable risk factors for QTc‐prolongation when indicated. Methods: This retrospective, cross‐sectional study evaluated clinician action at the time of prescribing prespecified medications with potential to prolong QTc in adult patients in primary care. The index date was defined as the date the medication was ordered. Electronic health record (EHR) data were evaluated to assess patient, clinician and visit characteristics. Clinician action was determined if baseline or follow‐up monitoring was ordered or if action was taken to mitigate modifiable risk factors (laboratory abnormalities or electrocardiogram [ECG] monitoring) within 48 h of prescribing a medication with QTc‐prolonging risk. Descriptive statistics were used to describe current practice. Results: A total of 399 prescriptions were prescribed to 386 patients, with a mean age of 51 ± 18 years, during March 2021 from a single‐centre, multisite health system. Of these, 17 (4%) patients had a known history of QTc‐prolongation, 170 (44%) did not have a documented history of QTc‐prolongation and 199 (52%) had an unknown history (no ECG documented). Thirty‐nine patients (10%) had at least one laboratory‐related risk factor at the time of prescribing, specifically hypokalemia (16 patients), hypomagnesemia (8 patients) or hypocalcemia (19 patients). Of these 39 patients with laboratory risk factors, only 6 patients (15%) had their risk acknowledged or addressed by a clinician. Additionally, eight patients' most recent QTc was ≥500 ms and none had an ECG checked at the time the prescription was ordered. Conclusion: Despite national recommendations, medication monitoring and risk mitigation is infrequent when prescribing QTc‐prolonging medications in the ambulatory care setting. These findings call for additional research to better understand this gap, including reasons for the gap and consequences on patient outcomes. [ABSTRACT FROM AUTHOR]

Four sphingosine 1‐phosphate (S1P) receptor modulators (fingolimod, ozanimod, ponesimod, and siponimod) are approved by the US Food and Drug Administration for the treatment of multiple sclerosis. This review summarizes efficacy and safety data on these S1P receptor modulators, with an emphasis on similarities and differences. Efficacy data from the pivotal clinical trials are generally similar for the four agents. However, because no head‐to‐head clinical studies were conducted, direct efficacy comparisons cannot be made. Based on the adverse event profile of S1P receptor modulators, continued and regular monitoring of patients during treatment will be instructive. Notably, the authors recommend paying attention to the cardiac monitoring guidelines for these drugs, and when indicated screening for macular edema and cutaneous malignancies before starting treatment. To obtain the best outcome, clinicians should choose the drug based on disease type, history, and concomitant medications for each patient. Real‐world data should help to determine whether there are meaningful differences in efficacy or side effects between these agents. [ABSTRACT FROM AUTHOR]

In this paper, we present the development and the validation of a novel index of nociception/anti-nociception (N/AN) based on skin impedance measurement in time and frequency domain with our prototype AnspecPro device. The primary objective of the study was to compare the Anspec-PRO device with two other commercial devices (Medasense, Medstorm). This comparison was designed to be conducted under the same conditions for the three devices. This was carried out during total intravenous anesthesia (TIVA) by investigating its outcomes related to noxious stimulus. In a carefully designed clinical protocol during general anesthesia from induction until emergence, we extract data for estimating individualized causal dynamic models between drug infusion and their monitored effect variables. Specifically, these are Propofol hypnotic drug to Bispectral index of hypnosis level and Remifentanil opioid drug to each of the three aforementioned devices. When compared, statistical analysis of the regions before and during the standardized stimulus shows consistent difference between regions for all devices and for all indices. These results suggest that the proposed methodology for data extraction and processing for AnspecPro delivers the same information as the two commercial devices. [ABSTRACT FROM AUTHOR]

Beta blockers (BBs) play a crucial role in enhancing the quality of life and extending the survival of patients with heart failure and reduced ejection fraction (HFrEF). Initiating the therapy at low doses and gradually titrating the dose upwards is recommended to ensure therapeutic efficacy while mitigating potential adverse effects. Vigilant monitoring for signs of drug intolerance is necessary, with dose adjustments as required. The management of older HF patients requires a case-centered approach, taking into account individual comorbidities, functional status, and frailty. Older adults, however, are often underrepresented in randomized clinical trials, leading to some uncertainty in management strategies as patients with HF in clinical practice are older than those enrolled in trials. The present article performs a scoping review of the past 25 years of published literature on BBs in older HF patients, focusing on age, outcomes, and tolerability. Twelve studies (eight randomized-controlled and four observational) encompassing 26,426 patients were reviewed. The results indicate that BBs represent a viable treatment for older HFrEF patients, offering benefits in symptom management, cardiac function, and overall outcomes. Their role in HF with preserved EF, however, remains uncertain. Further research is warranted to refine treatment strategies and address specific aspects in older adults, including proper dosing, therapeutic adherence, and tolerability. [ABSTRACT FROM AUTHOR]

Cancer medicines often have narrow therapeutic windows; toxicity can be severe and sometimes fatal, but inadequate dose intensity reduces efficacy and survival. Determining the optimal dose for each patient is difficult, with body‐surface area used most commonly for chemotherapy and flat dosing for tyrosine kinase inhibitors, despite accumulating evidence of a wide range of exposures in individual patients with many receiving a suboptimal dose with these strategies. Therapeutic drug monitoring (measuring the drug concentration in a biological fluid, usually plasma) (TDM) is an accepted and well validated method to guide dose adjustments for individual patients to improve this. However, implementing TDM in routine care has been difficult outside a research context. The development of genotyping of various proteins involved in drug elimination and activity has gained prominence, with several but not all Guideline groups recommending dose reductions for particular variant genotypes. However, there is increasing concern that dosing recommendations are based on limited data sets and may lead to unnecessary underdosing and increased cancer mortality. This Review discusses the evidence surrounding genotyping and TDM to guide decisions around best practice. [ABSTRACT FROM AUTHOR]

Background: Presently, there is limited guidance on the maximal dosing of psychosis drugs that is based on effectiveness rather than safety or toxicity. Current maximum dosing recommendations may far exceed the necessary degree of dopamine D2 receptor blockade required to treat psychosis. This may lead to excess harm through cognitive impairment and side effects. Aims: This analysis aimed to establish guidance for prescribers by optimally dosing drugs for psychosis based on efficacy and benefit. Methods: We used data from two dose–response meta-analyses and reviewed seven of the most prescribed drugs for psychosis in the UK. Where data were not available, we used appropriate comparison techniques based on D2 receptor occupancy to extrapolate our recommendations. Results: We found that the likely threshold dose for achieving remission of psychotic symptoms was often significantly below the currently licensed dose for these drugs. We therefore recommend that clinicians are cautious about exceeding our recommended doses. Individual factors, however, should be accounted for. We outline potentially relevant factors including age, ethnicity, sex, smoking status and pharmacogenetics. Additionally, we recommend therapeutic drug monitoring as a tool to determine individual pharmacokinetic variation. Conclusions: In summary, we propose a new set of maximum target doses for psychosis drugs based on efficacy. Further research through randomised controlled trials should be undertaken to evaluate the effect of reducing doses from current licensing maximums or from doses that are above our recommendations. However, dose reductions should be implemented in a manner that accounts for and reduces the effects of drug withdrawal. [ABSTRACT FROM AUTHOR]

Biomarkers are essential for clinical risk management in anorexia nervosa (AN). Biomarkers can inform decisions regarding AN treatment at specific steps during the therapeutic cycle. Biomarker research will help to define subgroups of people with AN and guide decisions on individually tailored therapies, including psychotherapy. Anti-hypothalamus autoantibodies, cytokines, and metabolically relevant hormones such as insulin and leptin may be novel future drug targets for the treatment of AN. Pharmacogenetic testing and therapeutic drug monitoring are available for research and clinical application in AN, but they are usually not utilized in clinical practice. In anorexia nervosa (AN), measurable biological parameters can inform the process of treating patients. Such biomarkers include established laboratory parameters as well as a range of potential future biomarkers, including genetic, metabolomic, microbiomic, endocrine, immunological, hematological, electrophysiological, and neuroimaging parameters. In this opinion article we discuss how these biomarkers can support diagnosic and therapeutic processes at specific steps during the AN treatment cycle, that is, the diagnosis, diagnostic specification, risk management, choice of therapy, therapy monitoring, and treatment review. History-taking, physical and neuropsychological examination, clinical observation, and judgment about treatment success by the patient, their carers, and members of the multidisciplinary team are essential to interpret laboratory and imaging data appropriately and to assess the full clinical picture. [ABSTRACT FROM AUTHOR]

Developing procedures based on equilibrium dialysis (ED) that allow measuring the free drug concentration in plasma improves therapeutic drug monitoring (TDM) in those cases where its measurement is justified. However, this procedure requires specific sample preparation and presents different pitfalls, which are not error-free. As with any result provided by a clinical laboratory, this one should be as accurate as possible to allow a correct clinical interpretation. The measurement uncertainty (MU) is a parameter that enables the accuracy of results to be known, and that is mandated by ISO 15189. Herein, this study suggests how the MU for the results of the free drug concentrations in serum could be estimated when an ED is used. A combination of the top-down and bottom-up approaches was used to estimate the MU based on the ISO/TS 20914:2019 and JCGM 100:2008 guidelines, including the concentration of free phenytoin in serum, as an example. Different scenarios were incorporated considering or not a significant bias related to the primary drawbacks of ED: the non-specific binding, the volume shift effect and the Gibbs-Donnan effect. The expanded uncertainties estimated ranged between 13.0 and 30.9 %. The highest MU corresponded to the free drug concentrations in serum results when significant biases related to the volume shift and Gibbs-Donnan effects exist. A detailed estimation of MU for free drug concentrations is presented using ED, considering different scenarios. This study could stimulate clinical laboratories to perform MU studies and its application in TDM. [ABSTRACT FROM AUTHOR]

The European Cooperation in Science and Technology (COST) action ENOTTA (The European Network on Optimising Treatment with Therapeutic Antibodies in chronic inflammatory diseases) was launched in 2022. To pave the way for harmonization of analytical methods for quantitation of serum levels of therapeutic antibodies in research and clinical settings, ENOTTA recently performed an online survey mapping laboratories in the field. The survey, which contained 30 questions surrounding therapeutic drug monitoring of relevant drugs and anti‐drug antibodies, was distributed via the ENOTTA and European Federation of Clinical Chemistry and Laboratory networks. Among 63 respondents across Europe, 45 reported analytical activity, with a range of utilized methods. Future engagement of as many sites as possible will enable comparison of methodologies and facilitate progress in the field. [ABSTRACT FROM AUTHOR]

Objective To develop and validate an UPLC–MS/MS assay for simultaneous determination of the total concentration of ceftazidime, ciprofloxacin, flucloxacillin, piperacillin, tazobactam, sulfamethoxazole, N -acetyl sulfamethoxazole and trimethoprim, and the protein-unbound concentration of flucloxacillin, in human plasma to be used for research and clinical practice. Methods Sample pretreatment included protein precipitation with methanol. For the measurement of protein-unbound flucloxacillin, ultrafiltration was performed at physiological temperature. For all compounds, a stable isotopically labelled internal standard was used. Reliability of the results was assessed by participation in an international quality control programme. Results The assay was successfully validated according to the EMA guidelines over a concentration range of 0.5–100 mg/L for ceftazidime, 0.05–10 mg/L for ciprofloxacin, 0.4–125 mg/L for flucloxacillin, 0.2–60 mg/L for piperacillin, 0.15–30 mg/L for tazobactam, 1–200 mg/L for sulfamethoxazole and N -acetyl sulfamethoxazole, 0.05–10 mg/L for trimethoprim and 0.10–50 mg/L for unbound flucloxacillin. For measurement of total concentrations, the within- and between-day accuracy ranged from 90.0% to 109%, and 93.4% to 108%, respectively. Within- and between-day precision (variation coefficients, CVs) ranged from 1.70% to 11.2%, and 0.290% to 5.30%, respectively. For unbound flucloxacillin, within-day accuracy ranged from 103% to 106% and between-day accuracy from 102% to 105%. The within- and between-day CVs ranged from 1.92% to 7.11%. Results of the international quality control programme showed that the assay is reliable. Conclusions The method provided reliable, precise and accurate measurement of seven commonly prescribed antibiotics, including the unbound concentration of flucloxacillin. This method is now routinely applied in research and clinical practice. [ABSTRACT FROM AUTHOR]

Background Isavuconazole is first-line treatment of invasive aspergillosis. Therapeutic drug monitoring (TDM) is deemed not necessary, since most patients reached therapeutic levels (>1 mg/L) in large studies. Low levels were reported in some critically ill patients admitted to the ICU. The aim was to compare isavuconazole levels between critically ill and non-critically ill patients. Materials and methods Retrospective analysis of data from all patients treated with standard-dose isavuconazole between 1 January 2019 and 26 October 2022 was performed. The following data were collected: TDM results from the first 30 days of therapy; ward of admission; demographic and clinical characteristics; continuous renal replacement therapy; extracorporeal membrane oxygenation; and co-administered drugs. Results Seventy-two patients (median age 65 years) and 188 TDM measurements (mean number of samples per patient 2.6 ± 1.7) were included; 33 (45.8%) were ICU patients (3 also had haematological disorders); 39 (54.2%) were non-ICU patients, of whom 31 had haematological disorders. In all patients, the mean isavuconazole blood level was 3.33 ± 2.26 mg/L. Significantly lower levels were observed in the ICU versus the non-ICU population: mean 2.02 ± 1.22 versus 4.15 ± 2.31 mg/L (P  < 0.001). Significantly higher rates of subtherapeutic levels were observed in ICU patients compared with the non-ICU population: all determinations <2 mg/L in 33.3% versus 7.7%, and all determinations <1 mg/L in 12.1% versus 0%, respectively. Predictors of lower isavuconazole levels were admission to the ICU, BMI > 25 kg/m2, bilirubin > 1.2 mg/dL and the absence of haematological disorder. Conclusions ICU patients had significantly lower isavuconazole blood levels compared to non-ICU population. The TDM of isavuconazole for efficacy should be performed in ICU. [ABSTRACT FROM AUTHOR]

Introduction Therapeutic drug monitoring (TDM) is a tool that supports personalized dosing, but its role for liposomal amphotericin B (L-amb) is unclear. This systematic review assessed the evidence for L-amb TDM in children. Objectives To evaluate the concentration–efficacy relationship, concentration–toxicity relationship and pharmacokinetic/pharmacodynamic (PK/PD) variability of L-amb in children. Methods We systematically reviewed PubMed and Embase databases following PRISMA guidelines. Eligible studies included L-amb PK/PD studies in children aged 0–18 years. Review articles, case series of 600 mg·h/L for nephrotoxicity. L-amb doses of 2.5–10 mg/kg/day were reported to achieve C max/MIC > 25 using an MIC of 1 mg/L. Conclusions While significant PK variability was observed in children, evidence to support routine L-amb TDM was limited. Further studies on efficacy and toxicity benefits are required before routine TDM of L-amb can be recommended. [ABSTRACT FROM AUTHOR]

Aims: Amikacin requires therapeutic drug monitoring for optimum efficacy; however, the optimal model‐informed precision dosing strategy for the area under the concentration–time curve (AUC) of amikacin is uncertain. This simulation study aimed to determine the efficient blood sampling points using the Bayesian forecasting approach for early achievement of the target AUC range for amikacin in critically ill patients. Methods: We generated a virtual population of 3000 individuals using 2 validated population pharmacokinetic models identified using a systematic literature search. AUC for each blood sampling point was evaluated using the probability of achieving a ratio of estimated/reference AUC at steady state in the 0.8–1.2 range. Results: On day 1, the 1‐point samplings for population pharmacokinetic models showed a priori probabilities of 26.3 and 45.6%, which increased to 47.3 and 94.4% at 23 and 15 h, respectively. Using 2‐point sampling at the peak (3 and 4 h) and trough (24 h) on day 1, these probabilities further increased to 72.3 and 99.5%, respectively. These probabilities were comparable on days 2 and 3, regardless of 3 and 6 sampling points or estimated glomerular filtration rate. These results indicated the higher predictive accuracy of 2‐point sampling than 1‐point sampling on day 1 for amikacin AUC estimation. Moreover, 2‐point sampling was a more reasonable approach than rich sampling. Conclusions: This study contributes to the development of an efficient model‐informed precision dosing strategy for early targeting of amikacin AUC in critically ill patients. [ABSTRACT FROM AUTHOR]

Aims: The pharmacokinetics of doravirine has been studied in clinical trials but not in real‐world settings. Our study aims to characterize and identify factors influencing doravirine (a CYP3A4 substrate) pharmacokinetics in real‐world people with HIV (PWH). Methods: A total of 174 doravirine concentrations measured in 146 PWH followed up in the therapeutic drug monitoring (TDM) program at the University Hospital of Lausanne (Switzerland) between 2019 and 2023 were included in the analysis. Demographic data, clinical information and comedications were recorded during the routine SHCS visits (every 3–6 months). Population pharmacokinetic analysis and Monte Carlo simulations to investigate the clinical significance of the covariates retained in the final model were performed using NONMEM. Results: A one‐compartment model with first‐order absorption and linear elimination best described doravirine pharmacokinetics. Potent CYP3A4 inhibitors and, to a lesser extent age, were the only tested covariates to significantly impact doravirine clearance (CL). Potent CYP3A4 inhibitors reduced CL by 50%, and a 30% decrease in CL was observed in an 80‐year‐old compared with a 55‐year‐old PWH. The effect of potent CYP3A4 inhibitors was prominent, explaining 59% of between‐subject variability in CL. Model‐based simulations predicted 2.8‐fold and 1.6‐fold increases in median steady‐state trough and maximum doravirine concentrations, respectively, when a potent CYP3A4 inhibitor was co‐administered. Conclusions: Our findings show that potent CYP3A4 inhibitors and age influence doravirine pharmacokinetics. However, given the good tolerability of doravirine, dosing adjustment of doravirine is probably not mandatory in those situations. TDM remains useful essentially in specific clinical situations, such as hepatic impairment, suspected nonadherence or pregnancy. [ABSTRACT FROM AUTHOR]

Hypokalemia and hyponatremia are common but easily ignored adverse events in treatment with voriconazole (VCZ) that can lead to serious consequences. We intend to investigate the incidence of VCZ‐induced hypokalemia and hyponatremia and their risk factors based on real‐world data. A prospective study was conducted. A total of 272 patients with 414 VCZ plasma trough concentrations (C0) and VCZ N‐oxide concentrations (CN) were included. The incidence of hypokalemia was 18.0% (48/266). A total of 81.2% (39/48) of patients developed hypokalemia within 14 days, whereas 56.2% (27/48) of patients developed hypokalemia within 1 week. The proportion of female patients in the hypokalemia group was higher than that in the nonhypokalemia group, as was the proportion of patients receiving intravenous VCZ. In the multivariate analysis, the independent risk factors for hypokalemia were sex, combined use of antibiotics, and VCZ CN/C0. The incidence of hyponatremia was 7.9% (21/266). The proportion of patients over 47 years of age in the hyponatremia group was 71.4% (15/21). The number of days of VCZ use in the hyponatremia group was greater than that in the nonhyponatremia group. A total of 47.6% (10/21) of patients in the hyponatremia group had supratherapeutic VCZ C0 (>5.0 µg/mL). In conclusion, hypokalemia is more likely to occur in females, in patients receiving intravenous VCZ, and in patients with the combined use of antibiotics. Hyponatremia is more likely to occur in patients older than 47 years who have been using VCZ for a long time and have higher VCZ C0 values. [ABSTRACT FROM AUTHOR]

Uveitis is a heterogeneous collection of infrequent diseases, which poses significant challenges to cost-effective research in the field. Medical registries are being increasingly recognized as crucial tools to provide high-quality data, thus enabling prospective clinical research. This paper describes the design and technical structure development of an innovative countrywide electronic medical record for uveitis, Uveite.pt, and gives an overview of the cohort registered since its foundation, March 2020. Uveite.pt is an electronic medical record platform developed by the Portuguese Ocular Inflammation Group (POIG), a scientific committee of the Portuguese Ophthalmology Society. This is a nationwide customized web-based platform for uveitis patients useful for both clinical practice and real-world-based research, working as a central repository and reporting tool for uveitis. This paper describes the technical principles, the design and the development of a web-based interoperable registry for uveitis in Portugal and provides an overview of more than 400 patients registered in the first 18 months since inception. In infrequent diseases, the existence of registries enables to gather evidence and increase research possibilities to clinicians. The adoption of this platform enables standardization and improvement of clinical practice in uveitis. It is useful to apprehend the repercussion of medical and surgical treatments in uveitis and scleritis, supporting clinicians in the strict monitoring of drug adverse reactions and surgical outcomes. [ABSTRACT FROM AUTHOR]

Purpose Telemedicine is underutilized in Saudi Arabia, which is a matter of concern, especially since previous literature has showed its equivalence with office visits in providing access to care and convenience for patients while reducing anticoagulation-related bleeding events when appropriate measures are followed. The purpose of this study is to analyze the efficacy of telehealth-based care compared to in-person visit care for warfarin follow-up. Methods The authors conducted a retrospective chart review comparing the mean percentage of time in the therapeutic range (TTR) of international normalized ratio (INR) values among patients prescribed warfarin from July 2019 to November 2020 at King Faisal Specialist Hospital & Research Center – Jeddah Branch whose anticoagulant therapy was managed via telemedicine or through in-person clinic visits. A subcohort analysis of outcomes in the telemedicine and in-person groups was performed using propensity score matching, and descriptive analysis was done for the entire cohort. Results A total of 350 patient records were included in this retrospective study. Matched analysis for 148 patients using propensity score matching showed that the mean (SD) percentages of TTR were 62.82% (19.46%) and 70.61% (19.83%) in the telemedicine and in-person groups, respectively (P = 0.017). There was no statistical difference in the incidence of major or minor bleeding events, thromboembolic events, and hospital readmission between the two groups. Conclusion The study results showed that patients on oral anticoagulation therapy managed through a telemedicine method had a lower overall TTR percentage than a matched group of patients managed through in-person anticoagulant clinic visits, thus demonstrating that using a telemedicine approach alone for warfarin follow-up may not help patients to maintain their INR target level. [ABSTRACT FROM AUTHOR]

Over the last decades, low vitamin B12 status has been reported in individuals with type 2 diabetes mellitus (T2DM). Metformin, the first-line therapy for lowering blood glucose, is the main driving factor behind this association. Although the relationship between vitamin B12 deficiency and metformin is well established, results of studies on the exact effect of the dose and duration of the therapy remain inconsistent. Additionally, a lack of consensus on the definition of vitamin B12 deficiency adds to the conflicting literature. The objectives of this review were to analyze and synthesize the findings on the effects of metformin dose and duration on vitamin B12 status in patients with T2DM and to outline the potential mechanisms underlying metformin's effect on vitamin B12. Metformin therapy has adversely affected serum vitamin B12 concentrations, a marker of vitamin B12 status. The metformin usage index (a composite score of metformin dose and duration) might serve as a potential risk assessment tool for vitamin B12 screening in patients with T2DM. Considering the health implications of suboptimal vitamin B12 status, vitamin B12 concentrations should be monitored periodically in high-risk patients, such as vegans who are receiving metformin therapy for T2DM. Additionally, it is prudent to implement lifestyle strategies concurrent with metformin therapy in individuals with T2DM, promoting an overall synergistic effect on their glycemic control. [ABSTRACT FROM AUTHOR]

Introduction: The mainstay of acute pulmonary embolism (PE) treatment is anticoagulation. Timely anticoagulation correlates with decreased PE‐associated mortality, but the ability to achieve a therapeutic activated partial thromboplastin time (aPTT) with unfractionated heparin (UFH) remains limited. Although some institutions have switched to a more accurate and reproducible test to assess for heparin's effectiveness, the anti‐factor Xa (antiXa) assay, data correlating a timely therapeutic antiXa to PE‐associated clinical outcomes remains scarce. We evaluated time to a therapeutic antiXa using intravenous heparin after PE response team (PERT) activation and assessed clinical outcomes including bleeding and recurrent thromboembolic events. Methods: This was a retrospective cohort study at NYU Langone Health. All adult patients ≥18 years with a confirmed PE started on IV UFH with >2 antiXa levels were included. Patients were excluded if they received thrombolysis or alternative anticoagulation. The primary endpoint was the time to a therapeutic antiXa level of 0.3–0.7 units/mL. Secondary outcomes included recurrent thromboembolism, bleeding and PE‐associated mortality within 3 months. Results: A total of 330 patients with a PERT consult were identified with 192 patients included. The majority of PEs were classified as sub massive (64.6%) with 87% of patients receiving a bolus of 80 units/kg of UFH prior to starting an infusion at 18 units/kg/hour. The median time to the first therapeutic antiXa was 9.13 hours with 93% of the cohort sustaining therapeutic anticoagulation at 48 hours. Recurrent thromboembolism, bleeding and mortality occurred in 1%, 5% and 6.2%, respectively. Upon univariate analysis, a first antiXa <0.3 units/ml was associated with an increased risk of mortality [27.78% (5/18) vs 8.05% (14/174), p = 0.021]. Conclusion: We observed a low incidence of recurrent thromboembolism or PE‐associated mortality utilizing an antiXa titrated UFH protocol. The use of an antiXa based heparin assay to guide heparin dosing and monitoring allows for timely and sustained therapeutic anticoagulation for treatment of PE. [ABSTRACT FROM AUTHOR]

Introduction: Antibiotic concentration target attainment is known to be poor in critically ill patients. Dose adjustment is recommended in patients with altered clearance, obesity and those with bacterial species with intermediate susceptibility. The aim of this study was to investigate the variation of antibiotic concentration in critically ill patients with standard or adjusted dosing regimens. Methods: The concentration of three beta‐lactam antibiotics used in the intensive care unit (ICU) setting, cefotaxime, piperacillin/tazobactam, and meropenem, was measured in patients with confirmed or suspected infection. Mid‐dose and trough values were collected during a single dosing interval. The pharmacokinetic endpoints were a free antibiotic concentration that, during the whole dosing interval, was above MIC (100% ƒT > MIC, primary endpoint) or above four times MIC (100% ƒT > 4MIC, secondary endpoint). Non‐species related MIC breakpoints were used (1 mg/L for cefotaxime, 8 mg/L for piperacillin/tazobactam, and 2 mg/L for meropenem). Results: We included 102 patients (38 cefotaxime, 30 piperacillin/tazobactam, and 34 meropenem) at a single ICU, with a median age of 66 years. In total, 73% were males, 40% were obese (BMI ≥30) and the median SAPS 3 score was 63 points. Of all patients, 78 patients (76%) reached the primary endpoint (100%ƒT > MIC), with 74% for cefotaxime, 67% for piperacillin/tazobactam and 88% for meropenem. Target attainment for 100% ƒT > 4MIC was achieved in 40 (39%) patients, overall, with 34% for cefotaxime, 30% for piperacillin/tazobactam and 53% for meropenem. In patients with standard dose 71% attained 100%ƒT > MIC and 37% for 100%ƒT > 4MIC. All patients with reduced dose attained 100%ƒT > MIC and 27% attained 100% ƒT > 4MIC. In patients with increased dose 79% attained 100%ƒT > MIC and 48% 100%ƒT > 4MIC respectively. Conclusions: Beta‐lactam antibiotics concentration vary widely in critically ill patients. The current standard dosing regimens employed during the study were not sufficient to reach 100% ƒT > MIC in approximately a quarter of the patients. In patients where dose adjustment was performed, the group with increased dose also had low target attainment, as opposed to patients with dose reduction, who all reached target. This suggests the need for further individualization of dosing where therapeutic drug monitoring can be an alternative to further increase target attainment. [ABSTRACT FROM AUTHOR]