Cost-Effectiveness of Therapeutic Drug Monitoring

Preliminary Investigation of a Rapid and Feasible Therapeutic Drug Monitoring Method for the Real-Time Estimation of Blood Pazopanib Concentrations

Pazopanib is a multi-kinase inhibitor used to treat advanced/metastatic renal cell carcinoma and advanced soft tissue tumors; however, side effects such as diarrhea and hypertension have been reported, and dosage adjustment based on drug concentration in the blood is necessary. However, measuring pazopanib concentrations in blood using the existing methods is time-consuming; and current dosage adjustments are made using the results of blood samples taken at the patient's previous hospital visit (approximately a month prior). If the concentration of pazopanib could be measured during the waiting period for a doctor's examination at the hospital (in approximately 30 min), the dosage could be adjusted according to the patient's condition on that day. Therefore, we aimed to develop a method for rapidly measuring blood pazopanib concentrations (in approximately 25 min) using common analytical devices (a tabletop centrifuge and a spectrometer). This method allowed for pazopanib quantification in the therapeutic concentration range (25-50 μg/mL). Additionally, eight popular concomitant medications taken simultaneously with pazopanib did not interfere with the measurements. We used the developed method to measure blood concentration in two patients and obtained similar results to those measured using the previously reported HPLC method. By integrating it with the point of care and sample collection by finger pick, this method can be used for measurements in pharmacies and patients' homes. This method can maximize the therapeutic effects of pazopanib by dose adjustment to control adverse events.

Dose Monitoring of Lamotrigine Monotherapy in Pregnancy: Are Pregnant Women with Epilepsy Currently Optimally Managed? A Systematic Review

BACKGROUND

Lamotrigine monotherapy is the first-line treatment for epilepsy in pregnant women. However, altered pharmacokinetics during pregnancy can lead to suboptimal drug levels and increased seizure risk. This systematic review aimed to evaluate current therapeutic drug monitoring (TDM) strategies for lamotrigine monotherapy in pregnant women with epilepsy and provide guidance for monitoring and dose adjustments.

METHODS

A systematic search was performed using the Ovid-MEDLINE, Ovid-EMBASE, and Ovid-Cochrane Central Register of Controlled Trials databases. Studies were included if data on lamotrigine dosing, concentration, TDM strategies, efficacy, or safety were available.

RESULTS

Eleven studies were analyzed, revealing heterogeneity in outcomes with selective reporting of TDM strategies; however, clear similarities were observed. Blood samples were collected every 1-3 months during pregnancy to maintain prepregnancy baseline drug levels. Lamotrigine's apparent and relative clearance increased across trimesters, particularly in the second and third trimesters, coinciding with a period of increased seizure frequency and required dose adjustments. Details on dose adjustments were limited. Some studies have proposed using the threshold of the ratio to the target concentration to predict increased seizure risk. No distinct association was observed between adverse newborn outcomes and lamotrigine dose or serum concentration. Few maternal adverse effects have been reported after delivery, confirming the necessity of empirical postpartum tapering.

CONCLUSIONS

Further studies are required to establish evidence-based standardized protocols encompassing all aspects of TDM. Early interventions, such as empirical dose increases during pregnancy and postpartum tapering, and routine monitoring from preconception to the postpartum period may enhance seizure control, reducing the risk of breakthrough seizures for the mother and unborn child.

Designing Molecularly Imprinted Polymer-Modified Boron-Doped Diamond Electrodes for Highly Selective Electrochemical Drug Sensors

Drug detection in biological solutions is essential in studying the pharmacokinetics of the body. Electrochemical detection is an accurate and rapid method, but measuring multiple drugs that react at similar potentials is challenging. Herein, we developed an electrochemical sensor using a boron-doped diamond (BDD) electrode modified with a molecularly imprinted polymer (MIP) to provide specificity in drug sensing. The MIP is a polymer material designed to recognize and capture template molecules, enabling the selective detection of target molecules. In this study, we selected the anticancer drug doxorubicin (DOX) as the template molecule. In the electrochemical measurements using an unmodified BDD, the DOX reduction was observed at approximately -0.5 V (vs Ag/AgCl). Other drugs, i.e., mitomycin C or clonazepam (CZP), also underwent a reduction reaction at a similar potential to that of DOX, when using the unmodified BDD, which rendered the accurate quantification of DOX in a mixture challenging. Similar measurements conducted in PBS using the MIP-BDD only resulted in a DOX reduction current, with no reduction reaction observed in the presence of mitomycin C and CZP. These results suggest that the MIP, whose template molecule is DOX, inhibits the reduction of other drugs on the electrode surface. Selective DOX measurement using the MIP-BDD was also possible in human plasma, and the respective limits of detection of DOX in PBS and human plasma were 32.10 and 16.61 nM. The MIP-BDD was durable for use in six repeated measurements, and MIP-BDD may be applicable as an electrochemical sensor for application in therapeutic drug monitoring.

The clinical application of beta-lactam antibiotic therapeutic drug monitoring in the critical care setting

Critically ill patients have increased variability in beta-lactam antibiotic (beta-lactam) exposure due to alterations in their volume of distribution and elimination. Therapeutic drug monitoring (TDM) of beta-lactams, as a dose optimization and individualization tool, has been recommended to overcome this variability in exposure. Despite its potential benefit, only a few centres worldwide perform beta-lactam TDM. An important reason for the low uptake is that the evidence for clinical benefits of beta-lactam TDM is not well established. TDM also requires the availability of specific infrastructure, knowledge and expertise. Observational studies and systematic reviews have demonstrated that TDM leads to an improvement in achieving target concentrations, a reduction in potentially toxic concentrations and improvement of clinical and microbiological outcomes. However, a small number of randomized controlled trials have not shown a mortality benefit. Opportunities for improved study design are apparent, as existing studies are limited by their inclusion of heterogeneous patient populations, including patients that may not even have infection, small sample size, variability in the types of beta-lactams included, infections caused by highly susceptible bacteria, and varied sampling, analytical and dosing algorithm methods. Here we review the fundamentals of beta-lactam TDM in critically ill patients, the existing clinical evidence and the practical aspects involved in beta-lactam TDM implementation.

Meropenem PK/PD Variability and Renal Function: "We Go Together"

BACKGROUND

Meropenem is a carbapenem antibiotic widely employed for serious bacterial infections. Therapeutic drug monitoring (TDM) is a strategy to optimize dosing, especially in critically ill patients. This study aims to show how TDM influences the management of meropenem in a real-life setting, not limited to intensive care units.

METHODS

From December 2021 to February 2022, we retrospectively analyzed 195 meropenem serum concentrations (Css). We characterized patients according to meropenem exposure, focusing on the renal function impact.

RESULTS

A total of 36% (n = 51) of the overall observed patients (n = 144) were in the therapeutic range (8-16 mg/L), whereas 64% (n = 93) required a meropenem dose modification (37 patients (26%) underexposed; 53 (38%) overexposed). We found a strong relationship between renal function and meropenem concentrations (correlation coefficient = -0.7; p-value < 0.001). We observed different dose-normalized meropenem exposure (Css/D) among renal-impaired (severe and moderate), normal, and hyperfiltrating patients, with a median (interquartile range) of 13.1 (10.9-20.2), 7.9 (6.1-9.5), 3.8 (2.6-6.0), and 2.4 (1.6-2.7), respectively (p-value < 0.001).

CONCLUSIONS

Meropenem TDM in clinical practice allows modification of dosing in patients inadequately exposed to meropenem to maximize antibiotic efficacy and minimize the risk of antibiotic resistance, especially in renal alterations despite standard dose adaptations.

Why is the Implementation of Beta-Lactam Therapeutic Drug Monitoring for the Critically Ill Falling Short? A Multicenter Mixed-Methods Study

BACKGROUND

Beta-lactam therapeutic drug monitoring (BL TDM; drug level testing) can facilitate improved outcomes in critically ill patients. However, only 10%-20% of hospitals have implemented BL TDM. This study aimed to characterize provider perceptions and key considerations for successfully implementing BL TDM.

METHODS

This was a sequential mixed-methods study from 2020 to 2021 of diverse stakeholders at 3 academic medical centers with varying degrees of BL TDM implementation (not implemented, partially implemented, and fully implemented). Stakeholders were surveyed, and a proportion of participants completed semistructured interviews. Themes were identified, and findings were contextualized with implementation science frameworks.

RESULTS

Most of the 138 survey respondents perceived that BL TDM was relevant to their practice and improved medication effectiveness and safety. Integrated with interview data from 30 individuals, 2 implementation themes were identified: individual internalization and organizational features. Individuals needed to internalize, make sense of, and agree to BL TDM implementation, which was positively influenced by repeated exposure to evidence and expertise. The process of internalization appeared more complex with BL TDM than with other antibiotics (ie, vancomycin). Organizational considerations relevant to BL TDM implementation (eg, infrastructure, personnel) were similar to those identified in other TDM settings.

CONCLUSIONS

Broad enthusiasm for BL TDM among participants was found. Prior literature suggested that assay availability was the primary barrier to implementation; however, the data revealed many more individual and organizational attributes, which impacted the BL TDM implementation. Internalization should particularly be focused on to improve the adoption of this evidence-based practice.

Building a monitoring matrix for the management of multiple sclerosis

Multiple sclerosis (MS) has a longitudinal and heterogeneous course, with an increasing number of therapy options and associated risk profiles, leading to a constant increase in the number of parameters to be monitored. Even though important clinical and subclinical data are being generated, treating neurologists may not always be able to use them adequately for MS management. In contrast to the monitoring of other diseases in different medical fields, no target-based approach for a standardized monitoring in MS has been established yet. Therefore, there is an urgent need for a standardized and structured monitoring as part of MS management that is adaptive, individualized, agile, and multimodal-integrative. We discuss the development of an MS monitoring matrix which can help facilitate data collection over time from different dimensions and perspectives to optimize the treatment of people with MS (pwMS). In doing so, we show how different measurement tools can combined to enhance MS treatment. We propose to apply the concept of patient pathways to disease and intervention monitoring, not losing track of their interrelation. We also discuss the use of artificial intelligence (AI) to improve the quality of processes, outcomes, and patient safety, as well as personalized and patient-centered care. Patient pathways allow us to track the patient's journey over time and can always change (e.g., when there is a switch in therapy). They therefore may assist us in the continuous improvement of monitoring in an iterative process. Improving the monitoring process means improving the care of pwMS.

Therapeutic drug monitoring of carbapenem antibiotics in critically ill patients: an overview of principles, recommended dosing regimens, and clinical outcomes

INTRODUCTION

The importance of antibiotic treatment for sepsis in critically ill septic patients is well established. Consistently achieving the dose of antibiotics required to optimally kill bacteria, minimize the development of resistance, and avoid toxicity is challenging. The increasing understanding of the pharmacokinetic and pharmacodynamic (PK/PD) characteristics of antibiotics, and the effects of critical illness on key PK/PD parameters, is gradually re-shaping how antibiotics are dosed in critically ill patients.

AREAS COVERED

The PK/PD characteristics of commonly used carbapenem antibiotics, the principles of the application of therapeutic drug monitoring (TDM), and current as well as future methods of utilizing TDM to optimally devise dosing regimens will be reviewed. The limitations and evidence-base supporting the use of carbapenem TDM to improve outcomes in critically ill patients will be examined.

EXPERT OPINION

It is important to understand the principles of TDM in order to correctly inform dosing regimens. Although the concept of TDM is attractive, and the ability to utilize PK software to optimize dosing in the near future is expected to rapidly increase clinicians' ability to meet pre-defined PK/PD targets more accurately, current evidence provides only limited support for the use of TDM to guide carbapenem dosing in critically ill patients.

A 5-Year Study of Antiseizure Medications (ASMs) Monitoring in Patients with Neuropsychiatric Disorders in an Italian Clinical Center

Despite receiving appropriate antiseizure medications (ASMs), a relevant percentage of neuropsychiatric patients do not benefit from this approach, and one reason is subtherapeutic ASMs plasma concentration (C(p)) due to improper drug adherence, interindividual pharmacokinetic differences, or metabolic interactions among different drugs. For these reasons, therapeutic drug monitoring (TDM) by measuring ASMs C(p) is an effective tool that improves pharmacological therapies in clinical practice. Based on these premises, in the present real-world study, we analyzed the C(p) of the most used ASMs in diverse medical conditions, which were assayed during the years 2018-2022 at the University Hospital of Pisa, including about 24,000 samples. This population was largely heterogeneous, and our database did not contain clinical information about the patients. The most used ASMs were Valproate (VPA: 54.5%) and Levetiracetam (LEV: 18.6%), followed by Oxcarbazepine (OxCBZ: 8.3%) and Carbamazepine (CBZ: 7.2%), whereas the associations LEV/VPA, Ethosuximide (ESM)/VPA, and CBZ/VPA were the most frequently proposed. In about 2/3 of assays, ASMs C(p) was in range, except for VPA, which was underdosed in almost half of the samples. Importantly, toxic levels of ASMs C(p) were found very rarely. For VPA, there was a decrease of mean C(p) across ages, from adolescents to older patients, while the C(p) of LEV, CBZ, OxCBZ, and Topiramate (TPM) showed a slight tendency to increase. When we compared females and males, we found that for VPA, the average age was higher for females, whereas women taking Lamotrigine (LTG) and OxCBZ were younger than men. Then, comparing ASMs used in neurologic and psychiatric disorders, based on the request form, it emerged that the mean C(p) of CBZ, OxCBZ, and LTG on samples collected in the Psychiatric Unit was lower compared to the Neurology and Child Neuropsychiatry Units. Finally, the ASMs subjected to multiple dosing starting from an initial subtherapeutic C(p) increased their level at different time points within a year, reaching the reference range for some of them. In conclusion, the present study suggests that TDM is widely applied to monitor ASMs C(p), finding many of them within the reference range, as a demonstration of its utility in clinical practice.

Mass spectrometry quantitation of immunosuppressive drugs in clinical specimens using online solid-phase extraction and accurate-mass full scan-single ion monitoring

Introduction

Therapeutic drug monitoring (TDM) of immunosuppressants is essential for optimal care of transplant patients. Immunoassays and liquid chromatography-mass spectrometry (LC-MS) are the most commonly used methods for TDM. However, immunoassays can suffer from interference from heterophile antibodies and structurally similar drugs and metabolites. Additionally, nominal-mass LC-MS assays can be difficult to optimize and are limited in the number of detectable compounds.

Objectives

The aim of this study was to implement a mass spectrometry-based test for immunosuppressant TDM using online solid-phase extraction (SPE) and accurate-mass full scan-single ion monitoring (FS-SIM) data acquisition mode.

Methods

LC-MS analysis was performed on a TLX-2 multi-channel HPLC with a Q-Exactive Plus mass spectrometer. TurboFlow online SPE was used for sample clean up. The accurate-mass MS was set to positive electrospray ionization mode with FS-SIM for quantitation of tacrolimus, sirolimus, everolimus, and cyclosporine A. MS² fragmentation pattern was used for compound confirmation.

Results

The method was validated in terms of precision, analytical bias, limit of quantitation, linearity, carryover, sample stability, and interference. Quantitation of tacrolimus, sirolimus, everolimus, and cyclosporine A correlated well with results from an independent reference laboratory (r = 0.926-0.984).

Conclusions

Accurate-mass FS-SIM can be successfully utilized for immunosuppressant TDM with good correlation with results generated by standard methods. TurboFlow online SPE allows for a simple "protein crash and shoot" sample preparation protocol. Compared to traditional MRM, analyte quantitation by FS-SIM facilitates a streamlined assay optimization process.

Multiphase electroextraction as a simple and fast sample preparation alternative for the digital image determination of doxorubicin in saliva

Monitoring chemotherapeutic drugs in biological fluids is, in many cases, extremely important for dose adjustment, the maintenance of therapies, and the control of side effects. In this work, a method for determining the doxorubicin in saliva by digital image analysis (DIA) was optimised and validated. Images from a paper point were obtained using a conventional and cheap flatbed scanner at a 600 ppp resolution. The RGB data channels were obtained from the images in a region of 15 × 15 pixels around the sorbent vertex. The paper point was used as sorbent material in sample preparation using a multiphase electroextraction system. Following optimisation using a Doehlert experimental design, the method was able to simultaneously extract 66 samples in 20 min. The high selectivity of the electric field associated with the sorption capacity of the cellulosic material allowed the chemotherapy drug to be pre-concentrated and quantified in a range between 50 and 500 μg L^-1 (R² > 0.98). The method also exhibited adequate parameters (limits of detection and quantification, recovery, and precision) indicating its potential application in the monitoring of doxorubicin and similar drugs in saliva.

Optimization of Antimicrobial Stewardship Programs Using Therapeutic Drug Monitoring and Pharmacokinetics-Pharmacodynamics Protocols: A Cost-Benefit Review

PURPOSE

Antimicrobial stewardship programs are important for reducing antimicrobial resistance because they can readjust antibiotic prescriptions to local guidelines, switch intravenous to oral administration, and reduce hospitalization times. Pharmacokinetics-pharmacodynamics (PK-PD) empirically based prescriptions and therapeutic drug monitoring (TDM) programs are essential for antimicrobial stewardship, but there is a need to fit protocols according to cost benefits. The cost benefits can be demonstrated by reducing toxicity and hospital stay, decreasing the amount of drug used per day, and preventing relapses in infection. Our aim was to review the data available on whether PK-PD empirically based prescriptions and TDM could improve the cost benefits of an antimicrobial stewardship program to decrease global hospital expenditures.

METHODS

A narrative review based on PubMed search with the relevant studies of vancomycin, aminoglycosides, beta-lactams, and voriconazole.

RESULTS

TDM protocols demonstrated important cost benefit for patients treated with vancomycin, aminoglycosides, and voriconazole mainly due to reduce toxicities and decreasing the hospital length of stay. In addition, PK-PD strategies that used infusion modifications to meropenem, piperacillin-tazobactam, ceftazidime, and cefepime, such as extended or continuous infusion, demonstrated important cost benefits, mainly due to reducing daily drug needs and lengths of hospital stays.

CONCLUSIONS

TDM protocols and PK-PD empirically based prescriptions improve the cost-benefits and decrease the global hospital expenditures.

Alternative Methods for Therapeutic Drug Monitoring and Dose Adjustment of Tuberculosis Treatment in Clinical Settings: A Systematic Review

BACKGROUND AND OBJECTIVE

Quantifying exposure to drugs for personalized dose adjustment is of critical importance in patients with tuberculosis who may be at risk of treatment failure or toxicity due to individual variability in pharmacokinetics. Traditionally, serum or plasma samples have been used for drug monitoring, which only poses collection and logistical challenges in high-tuberculosis burden/low-resourced areas. Less invasive and lower cost tests using alternative biomatrices other than serum or plasma may improve the feasibility of therapeutic drug monitoring.

METHODS

A systematic review was conducted to include studies reporting anti-tuberculosis drug concentration measurements in dried blood spots, urine, saliva, and hair. Reports were screened to include study design, population, analytical methods, relevant pharmacokinetic parameters, and risk of bias.

RESULTS

A total of 75 reports encompassing all four biomatrices were included. Dried blood spots reduced the sample volume requirement and cut shipping costs whereas simpler laboratory methods to test the presence of drug in urine can allow point-of-care testing in high-burden settings. Minimal pre-processing requirements with saliva samples may further increase acceptability for laboratory staff. Multi-analyte panels have been tested in hair with the capacity to test a wide range of drugs and some of their metabolites.

CONCLUSIONS

Reported data were mostly from small-scale studies and alternative biomatrices need to be qualified in large and diverse populations for the demonstration of feasibility in operational settings. High-quality interventional studies will improve the uptake of alternative biomatrices in guidelines and accelerate implementation in programmatic tuberculosis treatment.

The Appropriately Designed TDM Clinical Trial: Endpoints, Pitfalls, and Perspectives

BACKGROUND

Appropriately designed clinical trials can provide the evidence needed to broadly implement therapeutic drug monitoring (TDM). In the past 30 years, some stunning successes but also some fascinating failures in demonstrating the benefits of TDM have been observed. Future TDM studies can be designed based on this experience.

METHODS

The manuscript is based on a combination of personal experience and published articles and discusses several aspects of the design and conduct of TDM studies.

RESULTS

Recommendations are provided to reduce the risk of protocol violations and to maximize the potential impact of a TDM study on clinical practice.

CONCLUSIONS

There are lessons that can be learned from previous experience, and this article gives an overview of potential TDM study designs, endpoints, pitfalls, and perspectives.

Building clinical pharmacology laboratory capacity in low- and middle-income countries: Experience from Uganda

Background

Research and clinical use of clinical pharmacology laboratories are limited in low- and middle-income countries. We describe our experience in building and sustaining laboratory capacity for clinical pharmacology at the Infectious Diseases Institute, Kampala, Uganda.

Intervention

Existing laboratory infrastructure was repurposed, and new equipment was acquired. Laboratory personnel were hired and trained to optimise, validate, and develop in-house methods for testing antiretroviral, anti-tuberculosis and other drugs, including 10 high-performance liquid chromatography methods and four mass spectrometry methods. We reviewed all research collaborations and projects for which samples were assayed in the laboratory from January 2006 to November 2020. We assessed laboratory staff mentorship from collaborative relationships and the contribution of research projects towards human resource development, assay development, and equipment and maintenance costs. We further assessed the quality of testing and use of the laboratory for research and clinical care.

Lessons learnt

Fourteen years post inception, the clinical pharmacology laboratory had contributed significantly to the overall research output at the institute by supporting 26 pharmacokinetic studies. The laboratory has actively participated in an international external quality assurance programme for the last four years. For clinical care, a therapeutic drug monitoring service is accessible to patients living with HIV at the Adult Infectious Diseases clinic in Kampala, Uganda.

Recommendations

Driven primarily by research projects, clinical pharmacology laboratory capacity was successfully established in Uganda, resulting in sustained research output and clinical support. Strategies implemented in building capacity for this laboratory may guide similar processes in other low- and middle-income countries.

Therapeutic Drug Monitoring of Voriconazole in Children with Hematologic Malignancy and Invasive Fungal Infections: An RCT from a Tertiary Care Centre in India

INTRODUCTION

Voriconazole is a triazole anti-fungal with non-linear kinetics and a narrow therapeutic range. The objective of our study was to monitor the voriconazole serum levels in children with hematological malignancy and clinically suspected invasive fungal infections.

METHODS

The study was a prospective, randomized controlled trial conducted from June 2016 to December 2017. All children who had haematologic malignancies with clinically suspected invasive fungal infections and received voriconazole as the only anti-fungal were included in the study. The children were randomly allotted into two groups; one was the group that underwent TDM, and the other, TDM, was not done. Bioassay was the method employed for TDM. The trough levels were evaluated on a sample obtained on the fifth day of starting the drug. The institute's ethics committee approved the study.

RESULT

A total of 30 children were included in the study: 15 in the TDM group and 15 in the non-TDM group. The most common underlying malignancy was AML. Neutropenia due to chemotherapy sessions was these patients' most common risk factor. A favorable outcome was seen in 13/15 (86.7%) in the TDM group and 11/15 in the non-TDM group (73.3%).

CONCLUSION

Only five out of 15 (33.3%) children had voriconazole serum levels within the therapeutic range. Alterations in dose had to be done in the remaining to achieve the recommended serum levels. Thus, we recommend TDM for all children of hematologic malignancy receiving voriconazole for better management. Our findings also revealed that children with AML had lower than recommended levels of voriconazole on TDM evaluation, whereas those with ALL had normal to elevated levels of voriconazole.

Evaluation of drug prescribing patterns and therapeutic drug monitoring practice using electronic medical records

Therapeutic drug monitoring (TDM) is performed for drugs with narrow therapeutic indices. At Seoul National University Hospital (SNUH) and Seoul National University Bundang Hospital (SNUBH), TDM services are provided for various drugs such as antibiotics and antiepileptics. This study aimed to identify prescription patterns over time using electronic medical records and analyze their relationship with TDM practice. Data were collected from a clinical data warehouse from 2007 to 2020, and the number of patients, total number of drug administration days, serum level tests, and TDM were calculated. The ratio was calculated as the number of serum level tests or TDM to the total number of drug administration days. The study included 136,427 and 162,927 patients from SNUH and SNUBH who were prescribed 11 specified drugs. Each drug showed different prescription patterns over time, and the serum level test and TDM also changed with prescription pattern changes. Serum level test or TDM of antibiotics was frequently used compared to antiepileptics. As some drugs' usage and test for drugs have decreased newly developed drugs are replacing old drugs. It is recommended that TDM services include these new drugs as well for an effective and safe therapy.

Knowledge and Attitude of Healthcare Practitioners Toward Therapeutic Drug Monitoring Practices in the Najran Region, Kingdom of Saudi Arabia

BACKGROUND

Therapeutic drug monitoring (TDM) is one of the useful clinical tools that aim to improve and ensure the best therapeutic effects while avoiding drug-related toxicity. We aimed to evaluate the knowledge and attitude toward TDM practices among healthcare practitioners in the Najran region, Saudi Arabia.

METHODOLOGY

A cross-sectional study was conducted between May 2021 and October 2021 for assessing the awareness and attitude of licensed doctors and pharmacists working in Saudi Arabia regarding TDM practices. A 31-item questionnaire was distributed to the healthcare professionals via an electronic link. Descriptive and inferential statistics were used to report the data.

RESULTS

A total of 392 participants submitted questionnaires. More than half of the professionals (55.9%) had an overall awareness of the TDM, while only 3.1% did not. Only 16% and 23% of those who were surveyed indicated that TDM is used at the beginning of medication administration and when shifting from one drug to another, respectively. The majority of the professionals responded that TDM is revealed with laboratory changes in liver and kidney function (81%), and TDM is specified with suspected therapeutic failure (93%). Only half of the respondents claimed that they had ever requested or suggested a TDM in their practice. More than 90% of the respondents claimed that they were aware of the indications for vancomycin (n = 381), gentamicin (n = 375), lithium (n = 369), digoxin (n = 380), and theophylline (n = 369).

CONCLUSION

This study found that the majority of the healthcare professionals in Najran were aware of the TDM, particularly those with more than 10 years of professional experience. In addition, TDM service is not widely available in smaller hospitals in Najran. There is a need to conduct customized training programs for junior healthcare professionals, thus increasing the levels of awareness toward TDM. Future studies in Saudi Arabia can explore the role of clinical pharmacists in the provision of TDM services by assessing the clinical and economic outcomes of pharmacist interventions in TDM.

Therapeutic drug monitoring (TDM) as intervention: A cross-sectional analysis of characteristics of 173 registered clinical trials

Background

To examine fundamental characteristics of clinical trials with therapeutic drug monitoring (TDM) as intervention on world major clinical trials registry platform.

Methods

Cross-sectional analysis of clinical trials with TDM as intervention that were registered on WHO International Clinical Trials Registry Platform (ICTRP) or ClinicalTrials.gov. Relevant trial entries registered before and on March 2nd, 2022 were downloaded, deduplicated, and reviewed. Recruit country, monetary source, start years, study design, medical conditions, involved drugs, outcome measure, and subject information were extracted and analyzed.

Results

Overall, 173 clinical trials were included in this study. Majority of the trials were conducted in several economically prosperous countries. The earliest initiated trials dates back to 2002. Most of the trials were funded by hospitals (36.4%). A higher proportion of trials were conducted within one country (86.1%), as phase Ⅳ (34.1%) interventional study (82.7%), randomized (52.6%), parallel assignment (53.8%) and open label (67.0%). The most concerned medical condition were infectious or parasitic disease and neoplasms, with the most monitored drugs were immunosuppressants and β-lactam antibacterials. Most of the trials enroll no more than 50 subjects (30.6%), with both gender (95.4%), and adults (67.0%).

Conclusion

The trials were mainly conducted in several economically prosperous countries. The number of registered trials had gradually increased during the past years. Novel biological drugs have increasingly become the research hotspot. We expect that with abundant financial support, more high-quality large-scale, multicenter randomized clinical trials (RCTs) are designed and implemented to promote the development of TDM in the future.

High-throughput analysis for the simultaneous quantification of nine beta-lactam antibiotics in human plasma by UPC2-MS/MS: Method development, validation, and clinical application

Quantification of beta-lactam antibiotics can be performed by using liquid chromatography in combination with tandem mass spectrometry (MS/MS) or ultraviolet (UV) detection. Since beta-lactam antibiotics are known as highly polar analytes, using standard reversed phase chromatography will result in very early elution, which is often not desirable. Some retention is preferred to reduce matrix effects, because a high amount of non-retained molecular matrix species elute early from the column. For highly polar analytes, ultra-performance convergence chromatography (UPC²) may be a suitable alternative. This method is based on supercritical fluid chromatography. To our knowledge, we developed the first UPC²-MS/MS method for the determination of amoxicillin, benzylpenicillin, flucloxacillin, piperacillin, cefotaxime, cefuroxime, ceftazidime, imipenem, meropenem, and the free fraction of cefuroxime and flucloxacillin in human plasma. The method was validated according to the Food and Drug Administration guidelines. The method was found linear (r² >0.990) for all analytes. The inaccuracies and imprecisions were < 15% for all analytes. The matrix effect and recovery were nearly all consistent with coefficient of variation of less than 15% and no significant carryover effect was observed. Furthermore, this method was found to be suitable for daily routine analysis in hospital settings, requiring only 50 µL of plasma. This novel, sensitive, and specific UPC²-MS/MS method demonstrated its value in the analysis of a more than 800 human plasma samples in a clinical trial using simple and fast sample preparation and short analysis run time of only 5 min.

Drug monitoring in systemic lupus erythematosus

Therapeutic drug monitoring (TDM) is not yet accepted by systemic lupus erythematosus (SLE) treatment guidelines. Studies in SLE, however, have proven benefit in three areas: identification of non-adherence or poor adherence; targets for clinical benefit; and ranges of toxicity. This review covers the data on three medications commonly used for SLE, drawing on studies from both the SLE and non-SLE literature.

Systematic review and cost-effectiveness of pharmacokinetically guided sunitinib individualized treatment for patients with metastatic renal cell carcinoma

Background:

Sunitinib has a narrow therapeutic window, with considerable differences between patients. Dosing based on pharmacokinetics (PK) may help overcome some of those issues. This study aims to evaluate and compare the cost-effectiveness of PK-guided individualized treatment of sunitinib with its standard dose in patients with metastatic renal cell carcinoma (mRCC).

Methods:

A comprehensive literature search was performed, and relevant values were used to provide information for the decision analysis model. Utility data were derived from published studies, and costs were obtained from the perspective of payers in China and the United States. A Markov model was established to evaluate the associated costs and health outcomes for patients. The primary outputs of the model included lifetime costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER). One-way and probability sensitivity analyses were conducted to evaluate the potential uncertainties of parameters.

Results:

Cost-effective analysis showed that the QALY of the PK-guided group increased by 0.83 compared with that in the standard dose group. From the perspective of both countries’ health systems, the cost of PK-guided dose was lower than that of standard dose. Hence, PK-guided treatment was the dominant strategy. One-way and probability sensitivity analyses confirmed the reliability of these results.

Conclusion:

On the basis of currently available data, PK-guided sunitinib treatment may be a safe, effective, and economical intervention for patients with mRCC.

Protein-Induced Fluorescence Enhancement and Quenching in a Homogeneous DNA-Based Assay for Rapid Detection of Small-Molecule Drugs in Human Plasma

Homogeneous assays for determining the concentration of small molecules in biological fluids are of importance for monitoring blood levels of critical drugs in patients. We have developed a strand displacement competition assay for the drugs dabigatran, methotrexate, and linezolid, which allows detection and determination of the concentration of the drugs in plasma; however, a surprising kinetic behavior of the assay was observed with an initial rapid change in apparent FRET values. We found that protein-induced fluorescent enhancement or quenching (PIFE/Q) caused the initial change in fluorescence within the first minute after addition of protein, which could be exploited to construct assays for concentration determination within minutes in the low nanomolar range in plasma. A kinetic model for the assay was established, and when taking the new finding into account, the in silico simulations were in good agreement with the experimentally observed results. Utilizing these findings, a simpler assay was constructed for detection of dabigatran, which allowed for detection within minutes without any time dependencies.

[Therapeutic drug monitoring to optimize psychopharmacotherapy in children and adolescents - Update and guidelines for practice]

Therapeutic drug monitoring to optimize psychopharmacotherapy in children and adolescents - Update and guidelines for practice Abstract. Despite the improved evidence base, many uncertainties remain in child and adolescent psychiatric pharmacotherapy about the efficacy and tolerability of drugs, which are often prescribed off-label or in combination therapy in this age group. Because medium- to long-term use is unavoidable in many cases, clinicians should minimize adverse drug reactions as far as possible and tailor an effective dosage to the individual characteristics of the patient. Not only are children and adolescents particularly vulnerable to certain adverse drug effects, they are also exposed to iatrogenic risks from dosing or application errors, which can lead to under- or overdosing with correspondingly negative effects on the success of the therapy. In addition to determining a strict indication, it is therefore essential to establish precise dosage and systematic monitoring of the safety of the psychopharmacotherapy. This article introduces therapeutic drug monitoring as a useful clinical tool and describes how its correct application in practice can improve the efficacy as well as the safety and tolerability of psychotropic therapy in children and adolescents for the immediate benefit of patients. Keywords: Psychopharmacotherapy, adverse drug reactions, pharmacovigilance, therapeutic drug monitoring, quality assurance.

Health Care Costs of Target Attainment for Beta-Lactam Antibiotics in Critically Ill Patients: A Retrospective Analysis of the EXPAT Study

BACKGROUND

Optimizing beta-lactam antibiotic treatment is a promising method to reduce the length of intensive care unit (ICU) stay and therefore reduce ICU costs. We used data from the EXPAT trial to determine whether beta-lactam antibiotic target attainment is a cost determinant in the ICU.

METHODS

Patients included in the EXPAT trial were divided into target attainment and target nonattainment based on serum antibiotic levels. All hospital costs were extracted from the hospital administration system and categorized.

RESULTS

In total, 79 patients were included in the analysis. Target attainment showed a trend toward higher total ICU costs (€44,600 versus €28,200, P = 0.103). This trend disappeared when correcting for ICU length of stay (€2680 versus €2700). Renal replacement therapy was the most important cost driver.

CONCLUSIONS

Target attainment for beta-lactam antibiotics shows a trend toward higher total costs in ICU patients, which can be attributed to the high costs of a long stay in the ICU and renal replacement therapy.

Clinical Response and Hospital Costs of Therapeutic Drug Monitoring for Vancomycin in Elderly Patients

Cost-effectiveness analysis has been widely used to assess and compare the costs and benefits of a clinical service. The cost-effectiveness of vancomycin therapeutic drug monitoring (TDM) has not been studied in the elderly, who are susceptible to vancomycin-induced adverse effects. This study was performed to evaluate if vancomycin TDM is cost-effective in elderly patients in the Republic of Korea. Using the electronic medical records at a tertiary university hospital, we performed a retrospective observational study to evaluate the cost-effectiveness of vancomycin TDM in 850 elderly patients who underwent vancomycin TDM with an appropriate, recommended dosing regimen and 1094 elderly patients who did not. Cost-effectiveness variables such as clinical outcomes and medical expenses were evaluated using univariate and multivariate analyses. The TDM group spent significantly less than the non-TDM group per patient for total medical expenses (by USD 841.40) and medication expenses (by USD 16.70). However, no significant difference was noted between the TDM and non-TDM groups in clinical outcomes such as microbiological cure, prevention of nephrotoxicity, or reduced mortality, irrespective of admission to the intensive care unit. Vancomycin TDM in elderly patients was associated with economic benefits, but not with better clinical outcomes.

A 5-Year Study of Lithium and Valproic Acid Drug Monitoring in Patients with Bipolar Disorders in an Italian Clinical Center

Therapeutic drug monitoring (TDM) is an effective tool used to improve the pharmacological treatment in clinical practice, especially to detect subtherapeutic drug plasma concentration (Cp) in order to consider a change of dosage during treatment and reach its putative therapeutic range. In this study, we report the Cp values of lithium and valproic acid (VPA), alone and in combination, mostly in bipolar patients admitted to an Italian clinical center of the University of Pisa during the years 2016–2020, which include 12,294 samples of VPA, 7449 of lithium and 1118 of both in combination. Lithium and VPA are the most utilized drugs in treating bipolar disorders, and their TDM is strongly recommended by recent guidelines. In relation to lithium Cp monitoring, several studies have underlined that 0.5–0.8 mmol/L is the optimal range for chronic treatment, and below 0.4 mmol/L, it is unlikely to produce a clinical response. For VPA, the therapeutic range is 50–100 μg/mL and a linear correlation between Cp and clinical efficacy has been proposed, where below 50 μg/mL, the clinical efficacy of VPA has not been proven thus far. Toxic levels of both drugs were rarely found in our study, while a high percentage of patients, about one-third, had sub-therapeutic Cp during their treatments. In addition, in several cases of patients receiving multiple blood sampling, the initial subtherapeutic Cp changed only partially without reaching its therapeutic window. In relation to age, we found a higher percentage of lithium and VPA Cp values in range in the adolescents than in the adults and elderly groups. No differences were reported when analyzing the distribution of Cp values in males and females. In conclusion, this present study suggests that TDM is widely used by many specialists, but there is still a window of improvement for optimizing pharmacological treatments in clinical practice.

Combination of the lateral-flow immunoassay with multicolor gold nanorod etching for the semi-quantitative detection of digoxin

We demonstrated the first ever combination of the lateral-flow immunoassay (LFA) with gold nanorod etching to achieve a multicolor readout where the changes in color hue are more easily discernible than changes in intensity of a single color.

ABCB1 variants and sex affect serotonin transporter occupancy in the brain

Strategies to personalize psychopharmacological treatment promise to improve efficacy and tolerability. We measured serotonin transporter occupancy immediately after infusion of the widely prescribed P-glycoprotein substrate citalopram and assessed to what extent variants of the ABCB1 gene affect drug target engagement in the brain in vivo. A total of 79 participants (39 female) including 31 patients with major depression and 48 healthy volunteers underwent two PET/MRI scans with the tracer [¹¹C]DASB and placebo-controlled infusion of citalopram (8 mg) in a cross-over design. We tested the effect of six ABCB1 single nucleotide polymorphisms and found lower SERT occupancy in ABCB1 rs2235015 minor allele carriers (n = 26, MAF = 0.18) compared to major allele homozygotes (t₇₃ = 2.73, p_FWE < 0.05) as well as in men compared to women (t₇₃ = 3.33, p_FWE < 0.05). These effects were robust to correction for citalopram plasma concentration, age and diagnosis. From occupancy we derived the ratio of occupied to unoccupied SERT, because in theory this measure is equal to the product of drug affinity and concentration at target sites. A model combining genotype with basic clinical variables, predicted that, at the same dosage, occupied to unoccupied SERT ratio was -14.48 ± 5.38% lower in rs2235015 minor allele carriers, +19.10 ± 6.95% higher in women, -4.83 ± 2.70% lower per 10 kg bodyweight, and -2.68 ± 3.07% lower per 10 years of age. Our results support the exploration of clinical algorithms with adjustment of initial citalopram dosing and highlight the potential of imaging-genetics for precision pharmacotherapy in psychiatry.

Optimized Dosing: The Next Step in Precision Medicine in Non-Small-Cell Lung Cancer

In oncology, and especially in the treatment of non-small-cell lung cancer (NSCLC), dose optimization is often a neglected part of precision medicine. Many drugs are still being administered in "one dose fits all" regimens or based on parameters that are often only minor determinants for systemic exposure. These dosing approaches often introduce additional pharmacokinetic variability and do not add to treatment outcomes. Fortunately, pharmacological knowledge is increasing, providing valuable information regarding the potential of, for example, therapeutic drug monitoring. This article focuses on the evidence for the most promising and easily implemented optimized dosing approaches for the small-molecule inhibitors, chemotherapeutic agents, and monoclonal antibodies as treatment options currently approved for NSCLC. Despite limitations such as investigations having been conducted in oncological diseases other than NSCLC or the retrospective origin of many analyses, an alternative dosing regimen could be beneficial for treatment outcomes, prescriber convenience, or financial burden on healthcare systems. This review of the literature provides recommendations on the implementation of dose optimization and advice regarding promising strategies that deserve further research in NSCLC.

Educational intervention to improve appropriate digoxin therapeutic drug monitoring: a quasi-experimental study

OBJECTIVES

Our previous retrospecive study evaluating the appropriateness of serum digoxin concentration (SDC) measurements revealed errors in the timing of blood specimen collection in 98% of the tests. The aim of this study is to evaluate the appropriateness of the SDC measurements and the factors involved in inappropriate test-ordering, after training health personnel in digoxin therapeutic drug monitoring.

METHODS

This is a training-based quasi-experimental study. The residents and nurses of the Cardiology Clinic were trained first in December 2017, and refresher training courses were carried out every month throughout the study. The medical data of the inpatients receiving digoxin therapy were recorded prospectively, between January and December 2018. The appropriateness of the physicians' orders for SDC measurement was evaluated according to the criteria of the right indication and right timing of blood collection. The results are presented by descriptive statistics, Student's t-test and χ² analysis.

RESULTS

A total of 232 SDC tests were ordered for 121 patients (age: 71.0±12.6 years, 56.2% women). Of these orders,129 (55.6%) were considered appropriate: 205 (88.4%) for indication and 129 (62.9%) for blood collection timing. There was a significant correlation between inappropriate order for SDC test and the age of the patient, female gender, impairment of renal function tests, high levels of serum BNP and the number of medications used (P<0.005).

CONCLUSIONS

Approximately a one-half decrease in inappropriate tests compared with our previous study results imply that education has a positive effect on physician behaviour. However, physicians' concerns due to increased risk factors for the patient still play a role in inappropriate test-ordering.

Quality Control of Busulfan Plasma Quantitation, Modeling, and Dosing: An Interlaboratory Proficiency Testing Program

BACKGROUND

Personalizing busulfan doses to target a narrow plasma exposure has improved the efficacy and lowered the toxicity of busulfan-based conditioning regimens used in hematopoietic cell transplant. Regional regulations guide interlaboratory proficiency testing for busulfan concentration quantification and monitoring. To date, there have been no comparisons of the busulfan pharmacokinetic modeling and dose recommendation protocols used in these laboratories. Here, in collaboration with the Dutch Association for Quality Assessment in Therapeutic Drug Monitoring and Clinical Toxicology, a novel interlaboratory proficiency program for the quantitation in plasma, pharmacokinetic modeling, and dosing of busulfan was designed. The methods and results of the first 2 rounds of this proficiency testing are described herein.

METHODS

A novel method was developed to stabilize busulfan in N,N-dimethylacetamide, which allowed shipping of the proficiency samples without dry ice. In each round, participating laboratories reported their results for 2 proficiency samples (one low and one high busulfan concentrations) and a theoretical case assessing their pharmacokinetic modeling and dose recommendations. All participants were blinded to the answers; descriptive statistics were used to evaluate their overall performance. The guidelines suggested that answers within ±15% for busulfan concentrations and ±10% for busulfan plasma exposure and dose recommendation were to be considered accurate.

RESULTS

Of the 4 proficiency samples evaluated, between 67% and 85% of the busulfan quantitation results were accurate (ie, within 85%-115% of the reference value). The majority (88% round #1; 71% round #2) of the dose recommendation answers were correct.

CONCLUSIONS

A proficiency testing program by which laboratories are alerted to inaccuracies in their quantitation, pharmacokinetic modeling, and dose recommendations for busulfan in hematopoietic cell transplant recipients was developed. These rounds of proficiency testing suggests that additional educational efforts and proficiency rounds are needed to ensure appropriate busulfan dosing.

Rapid Simultaneous Determination of 14 Antidepressants and 13 Antipsychotics in Human Plasma by Using High-Performance Liquid Chromatography-Tandem Mass Spectrometry With Dynamic Multiple Reaction Monitoring and Its Application to Therapeutic Drug Monitoring

BACKGROUND

A comprehensive, stable, and efficient high-performance liquid chromatography-tandem mass spectrometry method was developed for rapidly analyzing 14 antidepressants and 13 antipsychotics in human plasma for routine clinical therapeutic drug monitoring.

METHODS

Simple protein precipitation was used for the pretreatment of plasma samples; dynamic multiple reaction monitoring was used to avoid the loss of sensitivity caused by numerous ion transitions. In all, 80 ion transitions of 40 compounds were quantitatively determined in 6 minutes.

RESULTS

The limit of detection for the 27 analytes was in the range of 0.1-30 ng/mL, and all calibration lines prepared using blank plasma were linear with a correlation coefficient of r2 ≥ 0.99. The method was accurate and precise with acceptable intraday and interday precisions (coefficients of variation, ≤20% for a lower limit of quantification and ≤15% for other quality control samples) and an accuracy of 85.51%-114.77%. This analysis method has been completely validated and successfully used in routine clinical therapeutic drug monitoring for more than 9963 samples [including 488 samples having drug concentrations above the laboratory alert level (supra-alert-level samples)] at Xiamen Xianyue Hospital.

CONCLUSIONS

This dynamic method is comprehensive (includes most antidepressants and antipsychotics listed in China), reliable (stably used for almost 2 years), and efficient (convenient sample processing and short run time) and provides a large amount of meaningful data for optimized pharmacotherapy. Our experimental data from the plasma concentrations of supra-alert-level samples could serve as a reference for the interpretation of the pharmacokinetics of patients with a high risk of toxicity or loss of tolerability.

Redefining the age-specific therapeutic ranges of lamotrigine for patients with epilepsy: A step towards optimizing treatment and increasing cost-effectiveness

OBJECTIVE

The pharmacokinetics of lamotrigine exhibits age-related characteristics. Nevertheless, current evidence regarding the therapeutic range of lamotrigine has been derived almost exclusively from studies in adult patients, and the applicability of this therapeutic range to the pediatric population remains unclear. The purpose of this study was to establish the appropriate age-specific therapeutic ranges of lamotrigine corresponding to adequate clinical responses for patients with epilepsy.

METHODS

This prospective cohort study of therapeutic drug monitoring included 582 Chinese epilepsy patients receiving lamotrigine monotherapy. Patients were divided into three age-related subgroups: (1) toddler and school-age group (2-12 years old, n = 168), (2) adolescent group (12-18 years old, n = 171), and (3) adult group (>18 years old, n = 243). Patients with a reduction in seizure frequency of 50 % or greater than baseline were defined as responders, and the remaining patients were non-responders. The relationship between lamotrigine serum concentrations and clinical response was assessed using multivariate logistic regression analysis. A receiver operating characteristic curve was generated to determine the representative cut-off values of lamotrigine trough levels, to distinguish responders from non-responders. The upper margin of the therapeutic range of lamotrigine was determined by developing concentration-effect curves for the three age-related subgroups.

RESULTS

The median trough levels of lamotrigine were significantly higher in responders than in non-responders from all three age-related groups (P < 0.0001). Results of logistic regression analysis revealed that higher serum concentrations of lamotrigine predicted a higher probability that seizure frequency would be reduced by more than 50 % compared to baseline (adjusted odds ratio: 1.228, 95 % CI: 1.137-1.327; P < 0.0001), and younger children were less likely to be responders (adjusted odds ratio: 1.027, 95 % CI: 1.012-1.043; P = 0.001). Based on a trade-off between sensitivity and specificity, the optimal cut-off values for lamotrigine trough concentrations corresponding to clinical response were 3.29 mg/L, 2.06 mg/L, and 1.61 mg/L in the toddler and school-age group, adolescent group, and adult group, respectively. By reducing interpatient variability, the results of the concentration-effect curves suggested no additional clinical benefit from a continued increase of doses for lamotrigine concentrations exceeding 9.08 mg/L, 8.43 mg/L, and 10.38 mg/L in the toddler and school-age group, adolescent group, and adult group, respectively. In conclusion, the therapeutic ranges of lamotrigine trough concentrations corresponding to adequate clinical response were 3.29-9.08 mg/L in the toddler and school-age group, 2.06-8.43 mg/L in the adolescent group, and 1.61-10.38 mg/L in the adult group.

CONCLUSIONS

The study determined age-specific therapeutic ranges corresponding to optimal clinical efficacy for lamotrigine. Our findings lay the foundation for catalyzing novel opportunities to optimize treatment and reduce therapeutic costs. Based on the age-specific therapeutic ranges identified in this study, individualized and cost-effective algorithms for lamotrigine treatment of epilepsy patients may be developed and validated in larger cohort studies of therapeutic drug monitoring.

Emerging therapeutic drug monitoring of anti-infective agents in Australian hospitals: Availability, performance and barriers to implementation

AIMS

The purpose of the study was to assess the status of emerging therapeutic drug monitoring (TDM) of anti-infective agents in Australian hospitals.

METHODS

A nationwide cross-sectional survey of all Australian hospitals operating in the public and private health sector was conducted between August and September 2019. The survey consisted of questions regarding institutional TDM practice for anti-infective agents and clinical vignettes specific to β-lactam antibiotics.

RESULTS

Responses were received from 82 unique institutions, representing all Australian states and territories. All 29 (100%) of principal referral (major) hospitals in Australia participated. Five surveys were partially complete. Only 25% (20/80) of hospitals had TDM testing available on-site for any of the eight emerging TDM candidates considered: β-lactam antibiotics, anti-tuberculous agents, flucytosine, fluoroquinolones, ganciclovir, human immunodeficiency virus (HIV) drugs, linezolid and teicoplanin. A considerable time lag was noted between TDM sampling and reporting of results. With respect to β-lactam antibiotic TDM, variable indications, pharmacodynamic targets and sampling times were identified. The three greatest barriers to local TDM performance were found to be (1) lack of timely assays/results, (2) lack of institutional-wide expertise and/or training and (3) lack of guidelines to inform ordering of TDM and interpretation of results. The majority of respondents favoured establishing national TDM guidelines and increasing access to dose prediction software, at rates of 89% and 96%, respectively.

CONCLUSION

Translating emerging TDM evidence into daily clinical practice is slow. Concerted efforts are required to address the barriers identified and facilitate the implementation of standardised practice.

Association of EPHX1 polymorphisms with plasma concentration of carbamazepine in epileptic patients: Systematic review and meta-analysis

BACKGROUND

Carbamazepine (CBZ) is a wildly used anti-epileptic drug (AED). Increasing evidence suggested that polymorphisms in Epoxide Hydrolase1 (EPHX1) gene are associated with the pharmacokinetics (PK) and pharmacodynamics (PD) of CBZ, albeit the results were inconsistent.

METHODS

A literature search on PubMed, Embase, and Cochrane Library was conducted to identify eligible studies published between 1974 and 2020. A meta-analysis was performed and the standardized mean difference (SMD) and 95% confidence interval (95% CI) were estimated using a random-effects model. The heterogeneity and leave-one-study-out sensitivity analyses of each article and the publication bias were also performed. All the statistical analyses were performed using STATA 14.0.

RESULTS

A total of 6 articles with 1746 subjects were included in this meta-analysis. A significant correlation was detected between EPHX1 rs1051740 T > C polymorphisms and decreased plasma concentration of CBZ (TT vs CC: SMD = 0.34, P < 0.001; TC vs CC: SMD = 0.35, P = 0.009). However, similar results were not detected in the comparison of TT vs. TC in the EPHX1 rs1051740 T > C variation (P = 0.637), while subgroup analyses showed an association with plasma CBZ concentration in the non-Asian group (P < 0.001, I² = 0.0%, Ph = 0.400). Although the association of EPHX1 rs2234922 A > G polymorphisms with plasma CBZ concentration was not detected (AA vs GG:SMD = 0.54, P = 0.102; AA vs AG:SMD = -0.05, P = 0.670; AG vs GG: SMD = 0.86, P = 0.107), subgroup analyses showed that the GG genotype EPHX1 rs2234922 was associated with increased plasma CBZ concentration in the Asian group (P = 0.005, I² = 48.6%, Ph = 0.143).

CONCLUSION

EPHX1 rs1051740 T > C and rs2234922 A > G are important genetic variants associated with plasma CBZ concentration. The role of EPHX1 polymorphisms in the interindividual variability of plasma CBZ concentration varied significantly among different ethnic groups, which should be considered during clinical validation and in future studies.

CYP3A5*3 polymorphism and age affect tacrolimus blood trough concentration in myasthenia gravis patients

The study aims to identify clinical factors affecting tacrolimus blood trough concentration (C0) in myasthenia gravis (MG) patients and to optimize the initial dose of tacrolimus in MG treatment. A total of 103 MG patients participated in this study, and their clinical factors, medication regimens, C0 values and CYP3A5*3 polymorphisms were collected in detail. We used a linear mixed model to analyze the effect of multiple factors on the dosage-weighted C0 (C0:D) and performed subgroup analyses to investigate the consistency of correlations between influencing factors and the C0:D ratios. Among all factors, CYP3A5*3 polymorphism and age showed a strong positive correlation with C0:D ratios. The C0:D ratios (ng/ml·mg^-1) were higher for CYP3A5*3/*3 than for CYP3A5*1 (mean difference: 1.038, 95% confidence interval [CI]: 0.820-1.256, P-value <0.001), and for age in the range of 45-64 and ≥ 65 years than for age < 45 years (mean difference [95% CI] and P-value: 0.531[0.257-0.805] and P-value <0.001, 0.703 [0.377-1.029] and P-value <0.001, respectively). The C0:D ratios were not related to corticosteroid dosage, body weight, sex, hematocrit or the concomitant use of calcium channel blockers. The consistencies of the correlations between C0:D ratios and CYP3A5*3 polymorphism or age were confirmed by subgroup analyses. Thus, CYP3A5*3 polymorphism and age should be considered in optimizing the initial dose of tacrolimus for MG treatment.

Monitoring for valproate and phenytoin toxicity in hypoalbuminaemia: A retrospective cohort study

AIMS

Equations to calculate albumin-adjusted total concentrations have been validated to correlate with measured free concentrations for both phenytoin and valproate, but there is a lack of data to assess correlation with clinical outcomes. We aimed to assess the association of hypoalbuminaemia and albumin-adjusted total concentrations with concentration-dependent toxicity for phenytoin and valproate and review the impact on management decisions following concentration monitoring in hypoalbuminaemia.

METHODS

Patients undergoing concentration monitoring for phenytoin or valproate between January and December 2018 were included. Patients were identified using a centralised laboratory database with data extracted from medical records.

RESULTS

Total phenytoin concentrations were measured for 144 patients, with hypoalbuminaemia (≤30 g L^-1 ) recorded in 59 (41%) patients. Albumin-adjusted phenytoin concentration >20 mg L^-1 was associated with increased neurological adverse effects (77% vs. 43%, P < .001). On logistic regression, higher albumin-adjusted phenytoin concentration was an independent risk factor for neurotoxicity (OR 1.06, 95% CI 1.01-1.12, P = .011). Total valproate concentrations were measured for 383 patients, with hypoalbuminaemia (≤30 g L^-1 ) noted in 53 (14%) patients. For the valproate cohort, hypoalbuminaemia (42% vs. 28%, P = .039) and albumin-adjusted valproate concentration >100 mg L^-1 (49% vs. 23%, P < .001) were both associated with increased neurotoxicity. On multiple logistic-regression, valproate daily dose (aOR = 1.01, 95% CI 1.00-1.02, P = .006) and albumin-adjusted valproate concentration (aOR 1.01, 95% CI 1.00-1.02, P = .033) were independent risk factors for neurotoxicity after accounting for confounders.

CONCLUSION

While measuring free drug concentrations in hypoalbuminaemia would be ideal, the adjustment equations can help identify vulnerable patients needing further assessment of potential concentration-dependent toxicity.

Electrochemical biosensors: a nexus for precision medicine

Precision medicine is a field with huge potential for improving a patient's quality of life, wherein therapeutic drug monitoring (TDM) can provide actionable insights. More importantly, incorrect drug dose is a common contributor to medical errors. However, current TDM practice is time-consuming and expensive, and requires specialised technicians. One solution is to use electrochemical biosensors (ECBs), which are inexpensive, portable, and highly sensitive. In this review, we explore the potential for ECBs as a technology for on-demand drug monitoring, including microneedles, continuous monitoring, synthetic biorecognition elements, and multi-material electrodes. We also highlight emerging strategies to achieve continuous drug monitoring, and conclude by appraising recent developments and providing an outlook for the field.

Pinacho D. Personalized Medicine for Antibiotics: The Role of Nanobiosensors in Therapeutic Drug Monitoring

Due to the high bacterial resistance to antibiotics (AB), it has become necessary to adjust the dose aimed at personalized medicine by means of therapeutic drug monitoring (TDM). TDM is a fundamental tool for measuring the concentration of drugs that have a limited or highly toxic dose in different body fluids, such as blood, plasma, serum, and urine, among others. Using different techniques that allow for the pharmacokinetic (PK) and pharmacodynamic (PD) analysis of the drug, TDM can reduce the risks inherent in treatment. Among these techniques, nanotechnology focused on biosensors, which are relevant due to their versatility, sensitivity, specificity, and low cost. They provide results in real time, using an element for biological recognition coupled to a signal transducer. This review describes recent advances in the quantification of AB using biosensors with a focus on TDM as a fundamental aspect of personalized medicine.

Carbon based nanomaterials for the detection of narrow therapeutic index pharmaceuticals

Precise detection of important pharmaceuticals with narrow therapeutic index (NTI) is very critical as there is a small window between their effective dose and the doses at which the adverse reactions are very likely to appear. Regarding the fact that various pharmacokinetics will be plausible while considering pharmacogenetic factors and also differences between generic and brand name drugs, accurate detection of NTI will be more important. Current routine analytical techniques suffer from many drawbacks while using novel biosensors can bring up many advantages including fast detection, accuracy, low cost with simple and repeatable measurements. Recently the well-known carbon Nano-allotropes including carbon nanotubes and graphenes have been widely used for development of different Nano-biosensors for a diverse list of analytes because of their great physiochemical features such as high tensile strength, ultra-light weight, unique electronic construction, high thermo-chemical stability, and an appropriate capacity for electron transfer. Because of these exceptional properties, scientists have developed an immense interest in these nanomaterials. In this case, there are important reports to show the effective Nano-carbon based biosensors in the detection of NTI drugs and the present review will critically summarize the available data in this field.

Pharmacokinetics of Enteric-Coated Mycophenolate Sodium in Lupus Nephritis (POEMSLUN)

BACKGROUND

Mycophenolate mofetil or enteric-coated mycophenolate sodium (EC-MPS) and steroids are used for induction and maintenance therapy in severe lupus nephritis. Blood concentrations of mycophenolic acid (MPA), the active metabolite of these drugs, vary among patients with lupus nephritis. The objective of this study was to examine whether concentration-controlled (CC) dosing (through therapeutic drug monitoring) of EC-MPS results in a higher proportion of participants achieving target exposure of MPA compared with fixed-dosing (FD). An additional aim of the study was to evaluate the influence of CC dosing on clinical outcomes.

METHODS

Nineteen participants were randomly assigned either to the FD or CC group. All the participants were eligible to have free and total measurements of MPA over a period of 8-12 hours on 3 different occasions. Area under the concentration-time curve between 0 and 12 hours (AUC0-12) was calculated using noncompartmental methods. Dose of EC-MPS was titrated according to AUC0-12 in the CC group.

RESULTS

Thirty-two AUC0-12 measurements were obtained from 9 FD and 9 CC participants. Large inter-patient variability was observed in both groups but was more pronounced in the FD group. There were no significant differences between FD and CC participants in any pharmacokinetic parameters across the study visits, except for total C0 (FD 2.0 ± 0.3 mg/L versus CC 1.1 ± 0.3; P = 0.01) and dose-normalized C0 (FD 2.9 ± 0.2 mg/L/g versus CC 2.1 ± 0.7 mg/L/g; P = 0.04) at the second visit and total AUC0-12 (FD 66.6 ± 6.0 mg·h/L versus CC 35.2 ± 11.4 mg·h/L; P = 0.03) at the third visit. At the first study visit, 33.3% of the FD and 11.1% of the CC participants achieved the target area under the concentration-time curve (P = 0.58). From the second visit, none of the FD participants, compared with all the CC participants, achieved target AUC0-12 (P = 0.01). More CC participants achieved remission compared with FD participants (absolute difference of -22.2, 95% confidence interval (Equation is included in full-text article.)0.19 to 0.55; P = 0.62). The mean free MPA AUC0-12 was significantly lower in those who had complete remission.

CONCLUSIONS

CC participants reached target AUC0-12 quicker. Larger studies are required to test clinical efficacy.

Pharmacogenomics, Pharmacokinetics and Circulating Proteins as Biomarkers for Bevacizumab Treatment Optimization in Patients with Cancer: A Review

Bevacizumab is a monoclonal antibody that targets VEGF-A and inhibits tumor angiogenesis. Bevacizumab is approved for the treatment of various cancer, including metastatic colorectal cancer (mCRC), ovarian cancer, lung cancer, and others. Thus, it is widely used in oncology, but contrary to other therapeutic classes, there is still a lack of validating predictive factors for treatment outcomes with these agents. In recent years, the research for factors predictive of anti-VEGF treatments and especially bevacizumab response has been one of the most competitive translational research fields. Herein, we review and present the available literature of the clinical use of biomarkers, pharmacogenomics (PG), and therapeutic drug monitoring (TDM) approaches that can be used for the optimization of bevacizumab use in the era of precision medicine.

Right Dose, Right Now: Development of AutoKinetics for Real Time Model Informed Precision Antibiotic Dosing Decision Support at the Bedside of Critically Ill Patients

Introduction

Antibiotic dosing in critically ill patients is challenging because their pharmacokinetics (PK) are altered and may change rapidly with disease progression. Standard dosing frequently leads to inadequate PK exposure. Therapeutic drug monitoring (TDM) offers a potential solution but requires sampling and PK knowledge, which delays decision support. It is our philosophy that antibiotic dosing support should be directly available at the bedside through deep integration into the electronic health record (EHR) system. Therefore we developed AutoKinetics, a clinical decision support system (CDSS) for real time, model informed precision antibiotic dosing.

Objective

To provide a detailed description of the design, development, validation, testing, and implementation of AutoKinetics.

Methods

We created a development framework and used workflow analysis to facilitate integration into popular EHR systems. We used a development cycle to iteratively adjust and expand AutoKinetics functionalities. Furthermore, we performed a literature review to select and integrate pharmacokinetic models for five frequently prescribed antibiotics for sepsis. Finally, we tackled regulatory challenges, in particular those related to the Medical Device Regulation under the European regulatory framework.

Results

We developed a SQL-based relational database as the backend of AutoKinetics. We developed a data loader to retrieve data in real time. We designed a clinical dosing algorithm to find a dose regimen to maintain antibiotic pharmacokinetic exposure within clinically relevant safety constraints. If needed, a loading dose is calculated to minimize the time until steady state is achieved. Finally, adaptive dosing using Bayesian estimation is applied if plasma levels are available. We implemented support for five extensively used antibiotics following model development, calibration, and validation. We integrated AutoKinetics into two popular EHRs (Metavision, Epic) and developed a user interface that provides textual and visual feedback to the physician.

Conclusion

We successfully developed a CDSS for real time model informed precision antibiotic dosing at the bedside of the critically ill. This holds great promise for improving sepsis outcome. Therefore, we recently started the Right Dose Right Now multi-center randomized control trial to validate this concept in 420 patients with severe sepsis and septic shock.