Therapeutic Drug Monitoring Strategy Research Articles

A novel strategy for therapeutic drug monitoring: application of biosensors to quantify antimicrobials in biological matrices.

Over the past few years, therapeutic drug monitoring (TDM) has gained practical significance in antimicrobial precision therapy. Yet two categories of mainstream TDM techniques (chromatographic analysis and immunoassays) that are widely adopted nowadays retain certain inherent limitations. The use of biosensors, an innovative strategy for rapid evaluation of antimicrobial concentrations in biological samples, enables the implementation of point-of-care testing (POCT) and continuous monitoring, which may circumvent the constraints of conventional TDM and provide strong technological support for individualized antimicrobial treatment. This comprehensive review summarizes the investigations that have harnessed biosensors to detect antimicrobial drugs in biological matrices, provides insights into the performance and characteristics of each sensing form, and explores the feasibility of translating them into clinical practice. Furthermore, the future trends and obstacles to achieving POCT and continuous monitoring are discussed. More efforts are necessary to address the four key 'appropriateness' challenges to deploy biosensors in clinical practice, paving the way for personalized antimicrobial stewardship.

Optimal Therapeutic Drug Monitoring Strategy for IV Aminoglycosides and IV Vancomycin in People with Cystic Fibrosis: A Systematic Review.

Given altered pharmacokinetics in people with cystic fibrosis (pwCF), there is debate regarding optimal strategies for therapeutic drug monitoring (TDM) for aminoglycosides and vancomycin administered intravenously. To determine the TDM strategy for IV aminoglycosides and IV vancomycin associated with optimal clinical outcomes in pwCF. Several databases (MEDLINE, Embase, CINAHL, Web of Science, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov ) were searched from inception to November 15, 2020, with searches rerun on February 13, 2023. Full articles evaluating TDM strategies and clinical outcomes in pwCF receiving IV aminoglycosides or IV vancomycin were included. Three studies met the inclusion criteria for IV aminoglycosides, and 1 study met the inclusion criteria for IV vancomycin. Data are presented with descriptive analyses. The available evidence is insufficient to determine an optimal TDM strategy for IV aminoglycoside or IV vancomycin therapy in pwCF.

Ustekinumab trough levels in children with Crohn's disease refractory to anti-tumor necrosis factor agents: a prospective case series of off-label use.

Background: Ustekinumab is used off-label in pediatric Crohn's disease refractory to anti-tumor necrosis factor. Data on optimal dosing, target trough levels, and potential benefit of therapeutic drug monitoring in children treated with ustekinumab are limited. Materials and Methods: We describe a series of six adolescents who consented to be treated with ustekinumab. We measured their trough levels, C-reactive protein, and fecal calprotectin before every administration. Results: Standard adult dosing was effective to achieve biochemical remission (fecal calprotectin < 250mg/kg) in one patient and clinical remission (resolution of symptoms) in another. The other four patients failed to respond on standard dosing and underwent intravenous re-induction and interval shortening to increase ustekinumab trough levels. This resulted in biochemical remission in one patient and clinical remission in another, suggesting an exposure-response relationship. The remaining two patients had no therapeutic benefit, and ustekinumab was discontinued. Conclusion: In this report, we show that ustekinumab can induce remission in pediatric patients with anti-tumor necrosis factor refractory Crohn's disease. It is worth escalating the dose before abandoning the drug as ineffective. Prospective studies in children are needed to determine long-term efficacy of ustekinumab, usefulness of therapeutic drug monitoring strategies, and, if applicable, optimal target trough levels.

Standardization and validation of a novel UPLC-MS/MS method to quantify first line anti-tuberculosis drugs in plasma and dried blood spots

Tuberculosis (TB) is a high-burden infectious disease with high prevalence and mortality rates. The first-line anti-TB drugs include isoniazid (INH), rifampicin (RMP), pyrazinamide (PZA), and ethambutol (EMB). At present, the standard method of blood sampling for therapeutic drug monitoring (TDM) analysis is venipuncture. Dried blood spots (DBS) are a minimally invasive method for collecting small quantities of whole blood from fingertips. The aim of the current study was to develop an ultrahigh-performance liquid chromatography technique coupled to tandem mass spectrometry (UPLC-MS/MS) for simultaneous quantification of the first-line anti-TB drugs in human plasma and DBS as a sampling alternative. The separation and detection conditions were optimized to quantify INH, RMP, PZA, and EMB in both matrices in an ACQUITY UPLC H Class system coupled to a XEVO TQD detector. Chromatographic separation was performed through an Acquity HSS T3 column (2.1 × 100 mm, 1.8 μm) with 0.1% formic acid in water and acetonitrile as the mobile phase. The total run time was 7 min for both methods, with retention time in plasma of 0.85, 1.22, 3.16, and 4.04 min and 0.74, 0.87, 0.97, and 4.16 min for EMB, INH, PZA, and RMP in DBS, respectively. The bioanalytical methods developed were proved selective, linear, precise, and accurate (inter- and intra-assay); the matrix effect was demonstrated to be within the established limits. Short- and long-term stability, freeze–thaw cycles for plasma, and short-term stability for DBS were established. A total of 15 patients with 46 ± 17 (mean ± SD) years old were included, and anti-TB drug concentrations were quantified on plasma and DBS as proof of concept. Based on RMP and INH plasma concentrations (Cp), and Bayesian estimation of individual pharmacokinetic parameters, a dose adjustment was necessary for 93% of patients. The slopes of the correlation lines between plasma and DBS concentrations of RMP, EMB, INH, and PZA were 0.5321, 0.8125, 0.5680, and 0.6791, respectively. Finally, significant correlations (p < 0.05) were observed between DBS and plasma concentrations for RMP (r2 = 0.6961), EMB (r2 = 0.4369), INH (r2 = 0.8675) and PZA (r2 = 0.7363). A simple, fast, and reliable UPLC-MS/MS method was developed to quantify first-line anti-TB drugs in plasma and DBS, which provides an easy sampling and storage to be applied as a new strategy for TDM in patients with TB.

Effects of combined test dose and therapeutic drug monitoring strategy in exposure-directed busulfan.

Although exposure-directed busulfan (BU) dosing can improve allogeneic hematopoietic stem cell transplantation outcomes, there is still large variability in BU exposure with test dose alone due to changes in BU clearance caused by drug interactions. We conducted a single-arm phase II trial using the combined test dose and therapeutic drug monitoring strategy (PK-guided group) and compared the outcomes with an external historical cohort receiving a fixed-dose (fixed-dose group). The first eight and second eight doses were adjusted based on the area under the blood concentration-time curve (AUC) of the test and first doses, respectively, targeting a total AUC of 82.1mg·h/L. All patients received either BU and cyclophosphamide conditioning (BU/CY) or fludarabine (FLU)-containing conditioning. The BU clearance at the first dose decreased more in patients receiving FLU than in those receiving BU/CY; however, BU clearance also declined over time in patients who received BU/CY. The simulated total AUC (sAUC) with test dose only was significantly higher in patients who received FLU than in those who received BU/CY, but sAUC with the combined strategy was comparable. The 100-day progression-free survival was 85.5% (95% confidence interval [CI]: 71.9-92.8%), and was not inferior to that in the fixed-dose group. For the FLU-containing regimens, the PK-guided group showed decreased relapse (0.0% vs. 26.9%, p = 0.03), and favorable overall survival (75.1% vs. 57.0%, p = 0.07) at 1year. The combined strategy effectively controlled the BU exposure close to the target levels, potentially improving efficacy, especially in patients receiving the FLU-containing regimen. Clinical evaluation of efficacy of dose-modified intravenous busulfan in allogeneic hematopoietic stem cell transplantation for hematological malignancy (#UMIN000014077, June 15th, 2014).

Current Role of Monoclonal Antibody Therapy in Pediatric IBD: A Special Focus on Therapeutic Drug Monitoring and Treat-to-Target Strategies

In the last two decades, biologicals have become essential in treating children and adolescents with inflammatory bowel disease. TNF-α inhibitors (infliximab, adalimumab and golimumab) are preferentially used. Recent studies suggest that early application of TNF-α inhibitors is beneficial to inducing disease remission and preventing complications such as development of penetrating ulcers and fistulas. However, treatment failure occurs in about one third of pediatric patients. Particularly, children and adolescents differ in drug clearance, emphasizing the importance of pharmacokinetic drug monitoring in the pediatric setting. Here, current data on the choice and effectiveness of biologicals and therapeutic drug monitoring strategies are reviewed.

Population PK/PD modelling of meropenem in preterm newborns based on therapeutic drug monitoring data.

Background: Preterm neonates rarely participate in clinical trials, this leads to lack of adequate information on pharmacokinetics for most drugs in this population. Meropenem is used in neonates to treat severe infections, and absence of evidence-based rationale for optimal dosing could result in mismanagement. Aim: The objective of the study was to determine the population pharmacokinetic (PK) parameters of meropenem in preterm infants from therapeutic drug monitoring (TDM) data in real clinical settings and to evaluate pharmacodynamics (PD) indices as well as covariates affecting pharmacokinetics. Materials and methods: Demographic, clinical and TDM data of 66 preterm newborns were included in PK/PD analysis. The NPAG program from the Pmetrics was used for modelling based on peak-trough TDM strategy and one-compartment PK model. Totally, 132 samples were assayed by high-performance liquid chromatography. Meropenem empirical dosage regimens (40-120mg/kg/day) were administered by 1-3-h IV infusion 2-3 times a day. Regression analysis was used to evaluate covariates (gestation age (GA), postnatal age (PNA), postconceptual age (PCA), body weight (BW), creatinine clearance, etc.) influenced on PK parameters. Results: The mean ± SD (median) values for constant rate of elimination (Kel) and volume of distribution (V) of meropenem were estimated as 0.31 ± 0.13 (0.3) 1/h and 1.2 ± 0.4 (1.2) L with interindividual variability (CV) of 42 and 33%, respectively. The median values for total clearance (CL) and elimination half-life (T1/2) were calculated as 0.22L/h/kg and 2.33h with CV = 38.0 and 30.9%. Results of the predictive performance demonstrated that the population model by itself gives poor prediction, while the individualized Bayesian posterior models give much improved quality of prediction. The univariate regression analysis revealed that creatinine clearance, BW and PCA influenced significantly T1/2, meropenem V was mostly correlated with BW and PCA. But not all observed PK variability can be explained by these regression models. Conclusion: A model-based approach in conjunction with TDM data could help to personalize meropenem dosage regimen. The estimated population PK model can be used as Bayesian prior information to estimate individual PK parameter values in the preterm newborns and to obtain predictions of desired PK/PD target once the patient's TDM concentration(s) becomes available.

Development of a Therapeutic Drug Monitoring Strategy for the Optimization of Vincristine Treatment in Pediatric Oncology Populations in Africa

Recent studies have reported ethnic differences in vincristine exposure and outcomes such as toxicity. This resulted in the hypothesis of subtherapeutic dosing in African children. To optimize individual treatment, a strategy to identify subtherapeutic exposure using therapeutic drug monitoring is essential. The aim of the current study was to develop a strategy for therapeutic drug monitoring of vincristine in African children to meet the following criteria: (1) identify patients with low vincristine exposure with sufficient sensitivity (>70%), (2) determine vincristine exposure with a limited sampling strategy design of 3 samples, and (3) allow all samples to be collected within 4 hours after administration. An in silico simulation study was performed using a previously described population pharmacokinetic model and real-life demographic dataset of Kenyan and Malawian pediatric oncology patients. Two different therapeutic drug monitoring strategies were evaluated: (1) Bayesian approach and (2) pharmacometric nomogram. The sampling design was optimized using the constraints described above. Sensitivity analysis was performed to investigate the influence of missing samples, erroneous sampling times, and different boundaries on the nomogram weight bands. With the Bayesian approach, 43.3% of the estimated individual exposure values had a prediction error of ≥20% owing to extremely high shrinkage. The Bayesian approach did not improve with alternative sampling designs within sampling constraints. However, the pharmacometric nomogram could identify patients with low vincristine exposure with a sensitivity, specificity, and accuracy of 75.1%, 76.4%, and 75.9%, respectively. The pharmacometric nomogram performed similarly for different weight bands. The pharmacometric nomogram was able to identify patients with low vincristine exposure with high sensitivity, with 3 blood samples collected at 1, 1.5, and 4 hours after administration. Missing samples should be avoided, and the 3 scheduled samples should be collected within 15, 5, and 15 minutes of 1, 1.5, and 4 hours after administration, respectively.

A203 EARLY PROACTIVE DRUG MONITORING STRATEGY OF INFLIXIMAB AS MONOTHERAPY FOR INFLAMMATORY BOWEL DISEASE IN PAEDIATRIC PATIENTS IS ASSOCIATED WITH GOOD SUSTAINED CLINICAL REMISSION

Abstract Background Monotherapy with Infliximab (IFX) can be as efficient as combotherapy with immunomodulators in the treatment and maintenance of remission for children with inflammatory bowel disease (IBD) if an early proactive therapeutic drug monitoring strategy is adequately performed. This strategy may allow optimization of blood levels of IFX in order to obtain a sustained clinical response. Purpose This study demonstrated that with appropriate early trough levels of IFX before dose #3 and dose #4 , monotherapy was very efficient in inducing remssion at week 52 . Method A retrospective study was conducted at CHU Sainte-Justine, Montréal,Canada .Children with IBD 2 to 18 years old diagnosed between 01/2018 and 06/2020 and treated with IFX less than 30 days after diagnosis were included .IFX blood levels were collected before the 3rd and/or 4th dose of IFX and regularly thereafter. Adjustments were done in IFX dose per infusion according to blood levels and clinical response. The primary outcome was clinical remission at one year after diagnosis.The secondary outcomes included: (1) At 52 weeks, the median (IQR) dose of IFX (mg/kg) and the intervals between IFX infusions ; (2) the median (IQR) number of IFX dose changes and the median (IQR) number of blood trough levels of IFX done. Result(s) 101 patients were included : 56.4% males; 81CD; 18 UC; 2 IBDU. Mean age at diagnosis was 13.2 years (IQR = 11.20 to 15. 20). Median time to IFX initiation after diagnosis was 5 days (IQR :3-14).Median IFX dose #1: was 8.4 mg/kg (IQR = 5. 8 to 10). 90% of patient had an IFX optimisation (increasing dose and/or shortening intervals) after dose 3 or dose 4. At week 52, 36,5% of patients were receiving IFX infusion every 4 weeks and 30,6% every 6 weeks. The median IFX dose per infusion was 8,9mg/kg (IQR = 7.4- 9,8 ). The IFX doses at week 52 varied greatly according to age at diagnosis The median number of IFX blood level dosage was 4 per patient over a year (IQR=3-5).At week 52, 83 patients (84.6%) achieved clinical remission with a median IFX level of 10.96 (7.05-15.59). 74 /83 (89%) were on monotherapy and 9/83(10.8%) on combotherapy Image Conclusion(s) Early treatment for IBD with IFX as monotherapy and an early proactive optimization strategy is associated with a good sustained steroid free clinical remissionAt week 52, 83 patients (84.6%) achieved clinical remission with a median IFX level of 10.96 (7.05-15.59). 74 /83 (89%) were on monotherapy and 9/83(10.8%) on combotherapy.The majority of the patients required IFX optimization during their first year of treatment. We therefore recommend to proactively monitor blood levels of IFX before the third and fourth dose of IFX and thereafter, in order to lower the risk of treatment failure and anti-infliximab antibodies occurrence. Please acknowledge all funding agencies by checking the applicable boxes below None Disclosure of Interest C. Girard: None Declared, S. Ackhar: None Declared, S. Sassine: None Declared, L. Chapuy: None Declared, P. Jantchou: None Declared, C. Deslandres Speakers bureau of: moderator and speaker Abbvie and Janssen

P730 Anti tumor necrosis factor treatment in Ulcerative Colitis: Real-world data and evaluation of current treatment targets (STRIDE II)

Abstract Background In 2021, the Selection of Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) initiative proposed updated recommendations for treatment targets for ulcerative colitis (UC) patients. The recommendations introduce clinical remission as a short/medium term target, normalisation of CRP and Fecal Calprotectin (FC) as an intermediate target, and advice that change of treatment should be considered if targets are not met. In this single-centre study, we report real-world experience with proactive therapeutic drug monitoring (TDM) strategy for UC patients with first-line anti tumor necrosis factor (TNFi) treatment, and reflect on how implementation of the STRIDE II recommendations might affect clinical practice. Methods Adult, biologically naïve UC patients starting TNFi between 2014 and 2021 at Oslo University Hospital were included in a medical chart review study, and data were recorded at three and twelve months. Clinical remission was defined as a patient-recorded outcome (PRO-2) ≤1. Biochemical remission was defined as CRP &amp;lt;5 mg/L and FC &amp;lt; 250 µg/g. Combined remission was defined as clinical and biochemical remission. Target serum drug levels were defined as ≥7.5 mg/L (adalimumab [ADA]) and ≥5 mg/L (infliximab [IFX]). Logistic regression was applied for association analyses. Results A total of 141 patients were included. Of these, 60% were male, median age was 25 years. In total, 67% received IFX and 32% received ADA. One third (n=39) patients discontinued TNFi or added a second biologic agent during follow-up and were considered in non-remission, resulting in 102 (72%) persistent patients. Percentages [95% CI] in remission at 3 and 12 months are summarized in Table 1, and for drug-persistent patients in Table 2. Target drug level at 3 months was associated with clinical remission at 12 months (OR 2.97, 95% CI [1.24 – 7.12]), biochemical remission at 12 months (OR 2.64, 95% CI [1.03 – 6.77]) but not with combined remission. In total, 125 dosage adjustments were recorded. Of these, 70 (56%) were classified as adjustments related only to serum drug levels. Conclusion Combined remission rates at 3 and 12 months for persistent patients suggest that 60% and 46% of our cohort should have been considered for a change of treatment according to the STRIDE II recommendations. A majority of dosage adjustments were made proactively, and as target drug levels at 3 months were associated with remission outcomes at 12 months, our data support the use of a proactive TDM strategy.

Population pharmacokinetics and limited sampling strategies of polymyxin B in critically ill patients.

To characterize the pharmacokinetics (PK) of polymyxin B in Chinese critically ill patients. The factors significantly affecting PK parameters are identified, and a limited sampling strategy for therapeutic drug monitoring of polymyxin B is explored. Thirty patients (212 samples) were included in a population PK analysis. A limited sampling strategy was developed using Bayesian estimation, multiple linear regression and modified integral equations. Non-linear mixed-effects models were developed using Phoenix NLME software. A two-compartment population PK model was used to describe polymyxin B PK. Population estimates of the volumes of central compartment distribution (V) and peripheral compartment distribution (V2), central compartment clearance (CL) and intercompartmental clearance (Q) were 7.857 L, 12.668 L, 1.672 L/h and 7.009 L/h. Continuous renal replacement therapy (CRRT) significantly affected CL, and body weight significantly affected CL and Q. The AUC0-12h of polymyxin B in patients with CRRT was significantly lower than in patients without CRRT. CL and Q increased with increasing body weight. A limited sampling strategy was suggested using a two-sample scheme with plasma at 0.5h and 8h after the end of infusion (C0.5 and C8) for therapeutic drug monitoring in the clinic. A dosing regimen should be based on body weight and the application of CRRT. A two-sample strategy for therapeutic drug monitoring could facilitate individualized treatment with polymyxin B in critically ill patients.

Population pharmacokinetics and limited sampling strategy for therapeutic drug monitoring of mycophenolate mofetil in Japanese patients with lupus nephritis

BackgroundMycophenolate mofetil (MMF), a prodrug of the immunosuppressive agent mycophenolic acid (MPA), is difficult to administer because of the pharmacokinetic complexity of MPA. Although dosage adjustment according to the 12-h area under the concentration–time curve (AUC0-12) is thought to be desirable, multiple blood samplings for AUC calculation may pose a clinical challenge. A limited sampling strategy (LSS) would provide a solution; however, little is known about MPA pharmacokinetics in lupus nephritis patients, especially in those with Asian backgrounds, or few, if any, LSSs are reported for them.MethodsThirty-four adult Japanese patients receiving MMF for lupus nephritis were examined retrospectively. MPA pharmacokinetics were investigated, and a PPK model was developed using Phoenix® NLME™ software. Single and double blood sampling strategies from Bayesian estimation using the PPK model and from multiple linear regression were compared. Tolerability was also evaluated.ResultsIn the pharmacokinetic analysis, renal function and serum albumin had significant effects on dose-normalized AUC0-12; and serum albumin, concomitant proton pump inhibitor (PPI) and iron/magnesium oxide did on dose-normalized maximum concentration. As a PPK model, a two-compartment model was developed with a transit absorption model and first-order elimination, in which creatinine clearance and serum albumin were covariates for MPA clearance. The double sampling strategy at 1 and 4 h by multiple linear regression showed the best agreement with the observed AUC0-12 (r2 = 0.885). Of the single sampling strategies, the one at 6 h by Bayesian estimation performed best (r2 = 0.769). The tolerability evaluation showed that correlations were suggested for gastrointestinal involvement.ConclusionsThe present study developed the first PPK model of MPA for Japanese lupus nephritis patients. As for LSSs, a double sampling strategy at 1 and 4 h by multiple linear regression would work best; when only a single blood sampling is allowed, a strategy at 6 h by Bayesian estimation using the PPK model developed in this study would be best. The LSSs good enough for clinical use may facilitate safer, more effective, and individualized therapy.

Evaluation of Vancomycin TDM Strategies: Prediction and Prevention of Kidney Injuries Based on Vancomycin TDM Results.

The current guidelines for therapeutic drug monitoring (TDM) of vancomycin suggest a target 24-hour area under the curve (AUC0-24) of 400 to 600 mg*h/L for serious methicillin-resistant Staphylococcus aureus infections. In this study, the predictabilities of acute kidney injury (AKI) of various TDM target parameters, target levels, and sampling methods were evaluated in patients who underwent TDM from January 2020 to December 2020. The AUC0-24 and trough values were calculated by both one- and two-point sampling methods, and were evaluated for the predictability of AKI. Among the AUC0-24 cutoff comparisons, the threshold value of 500 mg*h/L in the two sampling methods was statistically significant (P = 0.042) when evaluated for the predictability of AKI. Analysis by an receiver operating characteristic curve estimated an AUC0-24 cutoff value of 563.45 mg*h/L as a predictor of AKI, and was proposed as the upper limit of TDM target.

An Audit to Evaluate Vancomycin Therapeutic Drug Monitoring in a Neonatal Intensive Care Unit.

Therapeutic drug monitoring (TDM) is routinely used for optimization of vancomycin therapy, because of exposure-related efficacy and toxicity, in addition to significant variability in pharmacokinetics, which leads to unpredictable drug exposure. The aim of this study was to evaluate target attainment and TDM of vancomycin in neonates. The authors conducted a retrospective study and collected data from medical records of all neonates who received vancomycin therapy in the neonatal intensive care unit between January 2019 and December 2019. The primary outcome was the proportion of vancomycin courses that reached target trough concentrations of 10-20 mg/L based on appropriate TDM samples collection. Secondary outcomes included proportion of courses with appropriate dose and dose frequency, and proportion of patients who achieved target concentrations after the first dose adjustment. In total, 69 patients were included, with 129 vancomycin courses. The median initial vancomycin trough concentration was 12 (range: 4-36) mg/L. The target trough concentration was achieved in 75% of courses after the initial dose with appropriate TDM, and 84% of courses after TDM-guided dose adjustments. Patients were dosed appropriately in 121/129 courses and TDM was performed correctly according to protocol in 51/93 courses. A dose adjustment was performed in 18/29 courses, to increase target attainment. This study showed that there is a need for an increase in dose to improve target attainment. There is also a need to explore more effective TDM strategies to increase the proportion of neonatal patients attaining vancomycin target trough concentrations.

Imatinib Optimized Therapy Improves Major Molecular Response Rates in Patients with Chronic Myeloid Leukemia.

The registered dose for imatinib is 400 mg/d, despite high inter-patient variability in imatinib plasmatic exposure. Therapeutic drug monitoring (TDM) is routinely used to maximize a drug’s efficacy or tolerance. We decided to conduct a prospective randomized trial (OPTIM-imatinib trial) to assess the value of TDM in patients with chronic phase chronic myelogenous treated with imatinib as first-line therapy (NCT02896842). Eligible patients started imatinib at 400 mg daily, followed by imatinib [C]min assessment. Patients considered underdosed ([C]min < 1000 ng/mL) were randomized in a dose-increase strategy aiming to reach the threshold of 1000 ng/mL (TDM arm) versus standard imatinib management (control arm). Patients with [C]min levels ≥ 1000 ng/mL were treated following current European Leukemia Net recommendations (observational arm). The primary endpoint was the rate of major molecular response (MMR, BCR::ABL1IS ≤ 0.1%) at 12 months. Out of 133 evaluable patients on imatinib 400 mg daily, 86 patients had a [C]min < 1000 ng/mL and were randomized. The TDM strategy resulted in a significant increase in [C]min values with a mean imatinib daily dose of 603 mg daily. Patients included in the TDM arm had a 12-month MMR rate of 67% (95% CI, 51–81) compared to 39% (95% CI, 24–55) for the control arm (p = 0.017). This early advantage persisted over the 3-year study period, in which we considered imatinib cessation as a censoring event. Imatinib TDM was feasible and significantly improved the 12-month MMR rate. This early advantage may be beneficial for patients without easy access to second-line TKIs.

Solid phase extraction prior to non-aqueous capillary electrophoresis with ultraviolet detection as a valuable strategy for therapeutic drug monitoring of cabozantinib

Solid phase extraction (SPE) prior to non-aqueous capillary electrophoresis (NACE) with ultraviolet detection was used for the first time for the determination of cabozantinib (CBZ), the main drug used for the treatment of metastatic renal cancer, in urine. SPE was carried out in commercial C18 cartridges loaded with 8 mL of urine. Tamoxifen (TAM) was added as internal standard. After removal of the matrix with 8 mL of phosphate buffer (pH 7.0; 10 mM), 7 mL of MeOH:H2O (30:70; v/v) and 0.5 mL of MeOH, CBZ and TAM were eluted with 1.5 mL of methanol. The eluate was evaporated to dryness and reconstituted in background electrolyte (BGE). The CE method was carried out in a fused silica capillary (30 cm × 75 µm i.d.) at 19 °C at 10 kV with a BGE consisting of ammonium acetate (pH 7.0; 8 mM) containing 3 % acetic acid (v/v) in methanol.The preconcentration factor achieved was 5.3, and the limits of detection and quantification were 3.7 and 12 µg/L in urine, respectively. Linearity was observed up to 950 µg/L. Intra-day precision at 20, 400, and 850 µg/L of CBZ (n = 8) was below 10 % in peak areas. As for inter-day precision, no statistical differences were found in two consecutive days, according to the Snedecor “F” test (p > 0.05). Recovery studies in spiked urine samples ranged from 91.4 to 116.6 %.The present method was applied to samples from a patient under treatment with CBZ for metastatic renal cancer as an alternative to the current strategies for therapeutic drug monitoring.

Dose Individualization of Oral Multi-Kinase Inhibitors for the Implementation of Therapeutic Drug Monitoring.

Oral multi-kinase inhibitors have transformed the treatment landscape for various cancer types and provided significant improvements in clinical outcomes. These agents are mainly approved at fixed doses, but the large inter-individual variability in pharmacokinetics and pharmacodynamics (efficacy and safety) has been an unsolved clinical issue. For example, certain patients treated with oral multi-kinase inhibitors at standard doses have severe adverse effects and require dose reduction and discontinuation, yet other patients have a suboptimal response to these drugs. Consequently, optimizing the dosing of oral multi-kinase inhibitors is important to prevent over-dosing or under-dosing. To date, multiple studies on the exposure-efficacy/toxicity relationship of molecular targeted therapy have been attempted for the implementation of therapeutic drug monitoring (TDM) strategies. In this milieu, we recently conducted research on several multi-kinase inhibitors, such as sunitinib, pazopanib, sorafenib, and lenvatinib, with the aim to optimize their treatment efficacy using a pharmacokinetic/pharmacodynamic approach. Among them, sunitinib use is an example of successful TDM implementation. Sunitinib demonstrated a significant correlation between drug exposure and treatment efficacy or toxicities. As a result, TDM services for sunitinib has been covered by the National Health Insurance program in Japan since April 2018. Additionally, other multi-kinase targeted anticancer drugs have promising data regarding the exposure-efficacy/toxicity relationship, suggesting the possibility of personalization of drug dosage. In this review, we provide a comprehensive summary of the clinical evidence for dose individualization of multi-kinase inhibitors and discuss the utility of TDM of multi-kinase inhibitors, especially sunitinib, pazopanib, sorafenib, and lenvatinib.

Cost-Effectiveness of Therapeutic Drug Monitoring of Anti-TNF Therapy in Inflammatory Bowel Disease: A Systematic Review.

Infliximab and adalimumab are monoclonal antibodies against tumor necrosis factor (anti-TNF) used to manage inflammatory bowel disease (IBD). Therapeutic Drug Monitoring (TDM) has been proven to prevent immunogenicity, to achieve better long-term clinical results and to save costs in IBD treatment. The aim of this study was to conduct a systematic review on cost-effectiveness analyses of studies that apply TDM of anti-TNF in IBD and to provide a critical analysis of the best scientific knowledge available in the literature. The quality of the included studies was assessed using Consolidated Health Economic Evaluation Reporting Standards (CHEERS). Cost-effectiveness of the TDM strategies was presented as total costs, cost savings, quality-adjusted life-years (QALY) and incremental cost-effectiveness ratio (ICER). Thirteen studies that examined the health economics of TDM of anti-TNF in IBD from 2013 to 2021 were included. Eight of them (61.5%) achieved a score between 17 and 23 on the CHEERS checklist. The comparison between the TDM strategy and an empirical strategy was cost saving. The ICER between reactive TDM and an empirical strategy was dominated (favorable) by reactive TDM, whereas the ICER value for proactive TDM compared to an empirical strategy ranged from EUR 56,845 to 3,901,554. This systematic review demonstrated that a TDM strategy is cost-effective or cost-saving in IBD.

Therapeutic drug monitoring of vancomycin in neurosurgery patients, from trough concentration to area under the curve: a retrospective single center cohort study in a tertiary hospital.

ObjectiveTo evaluate the effect of therapeutic drug monitoring (TDM) of vancomycin in neurosurgery patients.MethodsIn this retrospective, single-center cohort study, data were collected from patients administered vancomycin after neurosurgery during 2020. Intervention by a pharmacist using an area under the curve (AUC)-based strategy for TDM of vancomycin was started on 1 July 2020. The trough concentration was monitored previously. Data regarding basic demographics, vancomycin application, and TDM were collected and analyzed.ResultsNinety and 155 samples were included in the non-intervention and intervention groups, respectively. No difference in baseline characteristics was detected. After intervention, the attainment rate of vancomycin TDM was significantly increased from 36.7% to 52.3%. The intervention resulted in an increased daily vancomycin dose (28.9 vs. 26.7 mg/kg/day), a more reasonable sample extraction time (sixth vs. ninth dose), reductions in dose adjustments (37.4% vs. 54.4%) and preventative applications (66.7% vs. 52.3%), and no difference in kidney function impact. The intervention group had a shorter hospital stay.ConclusionsIntervention by a clinical pharmacist using an AUC-based strategy for vancomycin TDM can provide benefits other than pharmacokinetic attainment in neurosurgery patients. Further prospective multi-center studies are needed to establish standardized intervention measures and evaluation indicators.

A Case Report of Excessive Use of Clozapine Combined With Clonazepam

IntroductionFor patients with schizophrenia, clozapine (CLZ) in combination with clonazepam (CLNAZ) is one of the viable therapeutic options. We successfully reduced the doses of CLZ and CLNAZ to the safe range of a polydrug abuse patient. As far as we know, this is the first case of this problem. As there are no relevant guidelines to reduce CLZ or CLNAZ, we hope to share this case to provide a reference for the prevention and treatment of similar patients with multidrug abuse.Case PresentationThis case report describes a 46-year-old male with a 24-year history of schizophrenia. His main clinical manifestations are auditory hallucinations, persecutory delusion, and emotional instability. In 2012, the patient started taking rifampicin due to tuberculosis and gradually overused CLZ and CLNAZ. Before admission, he took 1,275 mg of CLZ every day and 26 mg of CLNAZ every night. With the help of Therapeutic Drug Monitoring (TDM) and pharmacogenetic testing, we gradually reduced his daily dose of CLZ and CLNAZ and formulated a more reasonable dosing schedule for him. At the time of discharge, the patient took CLZ 450 mg per day and CLNAZ 2 mg per night, with no obvious symptoms of psychosis.ConclusionIn the process of drug maintenance treatment of schizophrenia, it is necessary to adopt TDM strategy to reduce and treat the abuse of multiple prescription drugs.