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Background and Purpose Experimental Approach Key Results Conclusion and Implications Bifunctional small molecule degraders, which link the target protein with E3 ubiquitin ligase, could lead to the efficient degradation of the target protein. BGB‐16673 is a Bruton's tyrosine kinase (BTK) degrader. A translational PK/PD modelling approach was used to predict the human BTK degradation of BGB‐16673 from preclinical in vitro and in vivo data.A simplified mechanistic PK/PD model was used to establish the correlation between the in vitro and in vivo BTK degradation by BGB‐16673 in a mouse model. Human and mouse species differences were compared using the parameters generated from in vitro human or mouse blood, and human or mouse serum spiked TMD‐8 cells. Human PD was then predicted using the simplified mechanistic PK/PD model.BGB‐16673 showed potent BTK degradation in mouse whole blood, human whole blood, and TMD‐8 tumour cells in vitro. Furthermore, BGB‐16673 showed BTK degradation in a murine TMD‐8 xenograft model in vivo. The PK/PD model predicted human PD and the observed BTK degradation in clinical studies both showed robust BTK degradation in blood and tumour at clinical dose range.The presented simplified mechanistic model with reduced number of model parameters is practically easier to be applied to research projects compared with the full mechanistic model. It can be used as a tool to better understand the PK/PD behaviour for targeted protein degraders and increase the confidence when moving to the clinical stage. [ABSTRACT FROM AUTHOR]

Aims Methods Results Conclusions PTC518 is an orally administered, centrally and peripherally distributed huntingtin (HTT) pre‐mRNA splicing modifier being developed for the treatment of Huntington's disease (HD) for which there is a high unmet medical need as there are currently no approved disease‐modifying treatments. This first‐in‐human study investigated the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of PTC518 in healthy volunteers.This phase 1, single‐centre, randomized study in 77 healthy male and female volunteers evaluated the safety and tolerability and PK of PTC518 following single ascending doses and multiple ascending doses, PD as assessed by HTT mRNA and HTT protein levels after single and multiple doses, and food effects.PTC518 demonstrated a favourable safety profile. The majority of treatment‐emergent adverse events were mild and transient. PTC518 Tmax was reached at 6–7 h and the terminal T1/2 was 54.0–75.3 h following a single oral dose. Exposure increased with dose though less than dose proportionally. The PTC518 concentrations in cerebrospinal fluid were approximately 2.6‐fold higher than the unbound free‐drug concentrations in plasma. A significant dose‐dependent reduction of up to approximately 60% in HTT mRNA and a significant dose‐dependent, time‐dependent and sustained reduction in HTT protein levels of up to 35% were observed after PTC518 treatment.PTC518 was well tolerated, and proof of mechanism of this novel splicing modifier was demonstrated by the dose‐dependent decrease in systemic HTT mRNA and HTT protein levels. Results from this first‐in‐human study support further studies in patients with HD and demonstrate the potential for PTC518 as a breakthrough treatment for HD. [ABSTRACT FROM AUTHOR]

Purpose: Gemcitabine and nab-paclitaxel (GnP) treatment, the standard first-line chemotherapy for unresectable pancreatic cancer, often causes peripheral neuropathy (PN). To develop alternative dosing strategies to avoid severe PN, understanding the relationship between pharmacokinetics (PK) and pharmacodynamics/toxicodynamics (PD/TD) is necessary. We established a PK-PD/TD model of GnP treatment to develop an optimal dose schedule. Methods: A mouse xenograft model of human pancreatic cancer was generated to measure drug concentrations in the plasma and tumor, antitumor effects, and PN after GnP treatment. The Simeoni tumor growth inhibition model with tumor concentrations and empirical indirect response models were used for the PD and TD models, respectively. Clinical outcomes were predicted with reported population estimates of PK parameters in cancer patients. Results: The PK-PD/TD model simultaneously described the observed tumor volume and paw withdrawal frequency in the von Frey test. For the standard GnP regimen, the model predicted clinical overall response (75.1%), which was overestimated compared to that in a recent phase II study (42.1%) but lower than the observed disease control rate (96.5%). Model simulation showed that dose reduction to less than 40% GnP dose was not effective; a change of dose schedule from every week for 3 weeks to every 2 weeks was a more favorable approach than dose reduction to 60% every week. Conclusion: The PK-PD/TD model-based translational approach provides a guide for optimal dose determination to avoid severe PN while maintaining antitumor effects during GnP chemotherapy. Further research is needed to enhance its applicability and potential for combination chemotherapy regimens. [ABSTRACT FROM AUTHOR]

Background/Aim: Osimertinib blood levels and their impact on treatment continuation in patients with EGFR mutation-positive lung cancer is not known. This study investigated the drug blood levels and risk factors affecting treatment continuation. Patients and Methods: Fifty-six patients with recurrent and inoperable epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer who received Osimertinib (80 mg once daily, daily dose) between October 1, 2016, and August 31, 2021, were included. Patients were classified into two groups using a cutoff blood level of 155 ng/ml. The primary endpoint was the relationship between Osimertinib exposure and efficacy, and secondary endpoints were the relationship between Osimertinib exposure and side effects, and the effect of covariates on efficacy and blood levels. Results: The median progression-free survival (PFS) for evaluable patients in the steady-state trough concentration (Cmin ss) ≥155 ng/ml and Cmin ss<155 ng/ml groups was 18.7 months and 31.2 months. Serum albumin (Alb) levels were 3.73±0.40 g/dl and 3.93±0.28 g/dl (p=0.030), respectively, and in multivariate analysis, Alb <3.7 g/dl was associated with a hazard ratio of 5.304 (95%CI=1.431-19.66; p=0.013), indicating that Alb <3.7 g/dl significantly shortened PFS. Conclusion: Free blood concentration of Osimertinib may have been increased by a combination of factors, including decreased hepatic metabolic function and decreased albumin production caused by systemic inflammation in patients with cancer. However, there was no effect of Osimertinib Cmin ss on PFS. [ABSTRACT FROM AUTHOR]

Rifapentine has facilitated treatment shortening for latent tuberculosis infection (LTBI) in combination with isoniazid once weekly for 3 months (3HP) or daily for 1 month (1HP). Our objective was to determine the optimal rifapentine dose for a 6-week monotherapy regimen (6wP) and predict clinical efficacy. Rifapentine and isoniazid pharmacokinetics were simulated in mice and humans. Mouse lung CFU data were used to characterize exposure-response relationships of 1HP, 3HP, and 6wP and translated to predict clinical efficacy. A 600-mg daily dose for 6wP delivered greater cumulative rifapentine exposure than 1HP or 3HP. The maximum regimen effect (Emax) was 0.24 day-1. The regimen potencies, measured as the concentration at 50% of Emax (EC50), were estimated to be 2.12 mg/liter for 3HP, 3.72 mg/liter for 1HP, and 4.71 mg/liter for 6wP, suggesting that isoniazid contributes little to 1HP efficacy. Clinical translation predicted that 6wP reduces bacterial loads at a higher rate than 3HP and to a greater extent than 3HP and 1HP. 6wP (600 mg daily) is predicted to result in equal or better efficacy than 1HP and 3HP for LTBI treatment without the potential added toxicity of isoniazid. Results from ongoing and future clinical studies will be required to support these findings.

Tuberculosis (TB) kills more people than any other infectious disease. Challenges for developing better treatments include the complex pathology due to within-host immune dynamics, interpatient variability in disease severity and drug pharmacokinetics-pharmacodynamics (PK-PD), and the growing emergence of resistance. Model-informed drug development using quantitative and translational pharmacology has become increasingly recognized as a method capable of drug prioritization and regimen optimization to efficiently progress compounds through TB drug development phases. In this review, we examine translational models and tools, including plasma PK scaling, site-of-disease lesion PK, host-immune and bacteria interplay, combination PK-PD models of multidrug regimens, resistance formation, and integration of data across nonclinical and clinical phases.We propose a workflow that integrates these tools with computational platforms to identify drug combinations that have the potential to accelerate sterilization, reduce relapse rates, and limit the emergence of resistance.

Background: Olaparib is given in a fixed dose of twice-daily 300 mg in patients who are diagnosed with ovarian cancer, breast cancer, prostate cancer or pancreas cancer and has a high interpatient variability in pharmacokinetic exposure. The objective of this study was to investigate whether pharmacokinetic exposure of olaparib is related to efficacy and safety in a real-life patient' cohort. Methods: A longitudinal observational study was conducted in patients who received olaparib for metastatic ovarian cancer of whom pharmacokinetic samples were collected. A Kaplan–Meier analyses was used to explore the relationship between olaparib exposure, measured as (calculated) minimum plasma concentrations (Cmin), and efficacy, Univariate and multivariate cox-regression analyses were performed. Also, the Cmin of patients who experienced toxicity was compared with patients who did not experience any toxicity. Results: Thirty-five patients were included in the exposure-efficacy analyses, with a median olaparib Cmin of 1514 ng/mL. There was no statistical significant difference in PFS of patients below and above the median Cmin concentration of olaparib, with a hazard ratio of 1.06 (95% confidence interval: 0.46–2.45, p = 0.9)). For seven patients pharmacokinetic samples were available before toxicity occurred, these patients had a higher Cmin of olaparib in comparison with patients who had not experienced any toxicity (n = 33), but it was not statistically significant (p = 0.069). Conclusions: Our study shows that exposure of olaparib is not related to PFS. This suggests that the approved dose of olaparib yields sufficient target inhibition in the majority of patients. [ABSTRACT FROM AUTHOR]

The search for new drugs is an extremely time-consuming and expensive endeavour. Much of that time and money go into generating predictive human pharmacokinetic profiles from preclinical efficacy and safety animal data. These pharmacokinetic profiles are used to prioritize or minimize the attrition at later stages of the drug discovery process. In the area of antiviral drug research, these pharmacokinetic profiles are equally important for the optimization, estimation of half-life, determination of effective dose, and dosing regimen, in humans. In this article we have highlighted three important aspects of these profiles. First, the impact of plasma protein binding on two primary pharmacokinetic parameters—volume of distribution and clearance. Second, interdependence of primary parameters on unbound fraction of the drug. Third, the ability to extrapolate human pharmacokinetic parameters and concentration time profiles from animal profiles. [ABSTRACT FROM AUTHOR]

Introduction: The environment of the infection site affects bacterial growth and antibiotic activity.When bacterial growth and antibiotic activity are studied in body fluids, samples of multiple subjects are usually pooled, averaging out potentially relevant differences in composition. The ascitic fluid (AF) environment is frequently associated with spontaneous bacterial peritonitis (SBP) in cirrhotic patients. In this study, bacterial growth and ceftriaxone activity were evaluated in individual AF using an in vitro model of SBP, reflecting the environment and pharmacokinetics at the infection site. Methods: AF was obtained from nine cirrhotic patients with non-infected ascites. Growth of nine bacterial strains (three Escherichia coli, four Staphylococcus aureus, one Enterococcus faecalis, and one Klebsiella pneumoniae)in individual AF was assessed and correlated with biomarkers including potential risk factors for SBP. Ceftriaxone time-kill experiments, in which the pharmacokinetic profile observed in AF following a 1 g intravenous infusion was replicated, were performed with two E. coli and two S. aureus isolates with minimum inhibitory concentrations around the ceftriaxone resistance breakpoint. Results: Significant correlations were found between bacterial growth and AF levels of protein (Spearman's rank correlation coefficient ρ = -0.35), albumin (ρ = -0.31), and complement C3c (ρ = -0.28), and serum levels of bilirubin (ρ = 0.39) and aspartate aminotransferase (ρ = 0.25). Ceftriaxone was active in AF, even against resistant isolates, generally resulting in ≥2 log reductions in bacterial count within 24 h. Conclusion: Ascites patients may be predisposed to or protected against SBP based on the antimicrobial capacity of their AF. Ceftriaxone at clinical AF concentrations is active in the AF environment. [ABSTRACT FROM AUTHOR]

Beta-lactam antibiotics remain one of the most preferred groups of antibiotics in critical care due to their excellent safety profiles and their activity against a wide spectrum of pathogens. The cornerstone of appropriate therapy with beta-lactams is to achieve an adequate plasmatic concentration of a given antibiotic, which is derived primarily from the minimum inhibitory concentration (MIC) of the specific pathogen. In a critically ill patient, the plasmatic levels of drugs could be affected by many significant changes in the patient's physiology, such as hypoalbuminemia, endothelial dysfunction with the leakage of intravascular fluid into interstitial space and acute kidney injury. Predicting antibiotic concentration from models based on non-critically ill populations may be misleading. Therapeutic drug monitoring (TDM) has been shown to be effective in achieving adequate concentrations of many drugs, including beta-lactam antibiotics. Reliable methods, such as high-performance liquid chromatography, provide the accurate testing of a wide range of beta-lactam antibiotics. Long turnaround times remain the main drawback limiting their widespread use, although progress has been made recently in the implementation of different novel methods of antibiotic testing. However, whether the TDM approach can effectively improve clinically relevant patient outcomes must be proved in future clinical trials. [ABSTRACT FROM AUTHOR]

Midazolam (MDZ) is a short-acting benzodiazepine that is widely used to induce and maintain general anesthesia during diagnostic and therapeutic procedures in pediatric patients due to its sedative properties. The aim of this study was to perform a systematic review without a meta-analysis to identify scientific articles and clinical assays concerning MDZ-induced sedation for a pediatric surgery approach. One hundred and twenty-eight results were obtained. After critical reading, 37 articles were eliminated, yielding 91 publications. Additional items were identified, and the final review was performed with a total of 106 publications.In conclusion, to use MDZ accurately, individual patient characteristics, the base disease state, comorbidities, the treatment burden and other drugs with possible pharmacological interactions or adverse reactions must be considered to avoid direct alterations in the pharmacokinetics and pharmacodynamics of MDZ to obtain the desired effects and avoid overdosing in the pediatric population.

This study evaluated the pharmacokinetics and pharmacodynamics of the antiplatelet agent prasugrel, and explored its optimal dose regimens via modeling and simulation using NONMEM. We measured platelet aggregation and the serial plasma concentrations of the inactive (R‐95913) and active metabolites (R‐138727) of prasugrel after a single oral dose of 10–60 mg in 20 healthy adult male volunteers. A pharmacokinetic model for R‐95913 and R‐138727, and a pharmacodynamic model between the concentration of R‐138727 and maximal platelet aggregation measured by light transmittance were constructed. The predictability of the model for platelet aggregation was evaluated by comparing the model prediction values with the observed ones not used in the construction of the model. Pharmacokinetic data were best described by a 3‐compartment models for R‐95913, a 1‐compartment model for R‐138727 with transit compartment model for absorption delay, and first‐pass metabolic conversion of R‐95913 into R‐138727 during absorption. The association–dissociation model between R‐138727 and its receptor in platelets was applied for the inhibitory effect of prasugrel on platelet aggregation. Prasugrel rapidly inhibited platelet aggregation after oral administration, with a prolonged duration of action; however, the concentration of the active metabolite decreased rapidly, which may have been due to the slow dissociation rate of R‐138727 from its target receptor in platelets. The external validation suggests that our model could be used to individualize prasugrel treatment in various clinical situations. Simulation showed rapid onset of inhibitory effect with great magnitude and consistent inhibition after therapeutic dose of prasugrel. [ABSTRACT FROM AUTHOR]

Background: Osimertinib, an irreversible inhibitor of the epidermal growth factor receptor (EGFR) is an important drug in the treatment of EGFR-mutation positive non-small cell lung cancer (NSCLC). Clinical trials with osimertinib could not demonstrate an exposure-efficacy relationship, while a relationship between exposure and toxicity has been found. In this study, we report the exposure–response relationships of osimertinib in a real-life setting. Methods: A retrospective observational cohort study was performed, including patients receiving 40 - 80 mg osimertinib as ≥ 2 line therapy and from whom pharmacokinetic samples were collected during routine care. Trough plasma concentrations (Cmin,pred) were estimated and used as a measure of osimertinib exposure. A previously defined exploratory pharmacokinetic threshold of 166 µg/L was taken to explore the exposure-efficacy relationship. Results: A total of 145 patients and 513 osimertinib plasma concentration samples were included. Median progression free survival (PFS) was 13.3 (95% confidence interval (CI):10.3 – 19.1) months and 9.3 (95% CI: 7.2 – 11.1) months for patients with Cmin,pred < 166 µg/L and Cmin,pred ≥ 166 µg/L, respectively (p = 0.03). In the multivariate analysis, a Cmin,pred < 166 µg/L resulted in a non-statistically significant hazard ratio of 1.10 (95% CI: 0.60 – 2.01; p = 77). Presence of a EGFR driver-mutation other than the exon 19 del or L858R mutations, led to a shorter PFS with a hazard ratio of 2.89 (95% CI: 1.18 – 7.08; p = 0.02). No relationship between exposure and toxicity was observed (p = 0.91). Conclusion: In our real-life cohort, no exposure–response relationship was observed for osimertinib in the current dosing scheme. The feasibility of a standard lower fixed dosing of osimertinib in clinical practice should be studied prospectively. [ABSTRACT FROM AUTHOR]

Little is known about how opioid responses vary by age and in the presence of alcohol consumption. This model‐based pharmacokinetic (PK)‐pharmacodynamic (PD) analysis quantified the impact of age and alcohol use on pupillometry and cold pressor test (CPT) PD based on data from an open‐label study of a single, immediate‐release 10‐mg oral oxycodone in middle‐age and older adults (aged 35‐85) without severe functional limitations. PK and pupillometry assessments were obtained on 11 occasions over 8 hours. Cold pressor test was administered at 1.5, 5, and 8 hours after oxycodone dosing. The study population consisted of 62 older adults (aged ≥60) and 66 middle‐aged adults (aged 35‐59), with 82% meeting the unhealthy drinking criteria. Oral oxycodone PK were well described using a 1‐compartment model with a sequential 0 to first‐order absorption process. Inhibitory maximum effect and linear direct effect PD models described the respective pupillometry and cold pressor test data using simultaneous PK‐PD analysis in MONOLIX. Recent alcohol use measures were selected a priori as covariates. This analysis demonstrated an influence of age on clearance and body weight on the distribution volume of oxycodone; alcohol consumption was not noted to alter oxycodone PK. Oxycodone pupillometry PD were influenced by the level of subject‐reported alcohol consumption (Alcohol Use Disorders Identification Test for Consumption), alcohol use biomarker–blood phosphatidylethanol, previous cannabis use, and age. Over the opioid exposure range of the study, none of the covariables including alcohol and age were noted to affect cold pressor test pharmacodynamics. Additional clinical studies are needed to further investigate the clinical consequences of opioid‐alcohol‐age interaction. [ABSTRACT FROM AUTHOR]

A patient developed a post-neurosurgical ventriculitis with carbapenem-resistant Klebsiella pneumoniae and mold, initially treated with ceftazidime/avibactam and voriconazole. A Klebsiella pneumoniae carbapenemase mutation led to therapy adjustment to ceftazidime/avibactam and polymyxin B, achieving cure. Pharmacokinetic/pharmacodynamic analysis highlights effective ceftazidime/avibactam's brain penetration and bacterial clearance efficacy., Competing Interests: Declaration of competing interest All authors report no potential conflicts., (Copyright © 2024. Published by Elsevier Ltd.)

Pharmacokinetic-pharmacodynamic (PK-PD) relationships for efficacy were evaluated using data from omadacycline-treated patients with acute bacterial skin and skin structure infections (ABSSSI) enrolled in two phase 3 studies. Patients received omadacycline 100 mg intravenously (IV) every 12 hours for two doses, followed by 100 mg IV every 24 hours (q24h), with the option to switch to 300 mg oral (PO) q24h after 3 days or 450 mg PO q24h for two doses, followed by 300 mg PO q24h for a total duration of 7-14 days. Clinical response was evaluated at 48-72 hours [early clinical response (ECR)], end of treatment (EOT), and 7-14 days after EOT. Using a population pharmacokinetic (PK) model and PK data from patients with Staphylococcus aureus at baseline, omadacycline free-drug plasma area under the concentration-time curve (AUC) values were determined, and the relationships between free-drug plasma AUC:MIC ratio and dichotomous efficacy endpoints were evaluated. Using these relationships, the population PK model, simulation, and an omadacycline MIC distribution for S. aureus , mean percent probabilities of response were evaluated. Statistically significant PK--PD relationships were identified for ECR ( P = 0.016 and 0.013 for optimized two- and three-group free-drug plasma AUC:MIC ratios, respectively). At an MIC value of 0.5 µg/mL, percent probabilities of model-predicted success for ECR based on the univariable PK-PD relationships using continuous and two-group free-drug plasma AUC:MIC ratio variables were 91.9 and 95.6%, respectively, for the IV-to-PO dosing regimen and 89.3 and 88.4%, respectively, for the PO-only dosing regimen. These data support for omadacycline IV-to-PO and PO-only dosing regimens for ABSSSI and an omadacycline susceptibility breakpoint of 0.5 µg/mL for S. aureus ., Competing Interests: S.M.B., J.P.H., K.L., C.M.R., and P.G.A. are employees of the Institute for Clinical Pharmacodynamics, Inc., which has received research support from Paratek Pharmaceuticals, Inc. E.A.L. was an employee of ICPD at the time the analyses were conducted and is currently an employee of Vertex Pharmaceuticals, Inc. M.T. was an employee of ICPD at the time the analyses were conducted and is currently an employee of Janssen Research and Development LLC, a Johnson and Johnson company. L.F. was an employee of Paratek Pharmaceuticals, Inc., at the time the analyses were conducted and is currently an employee of AN2 Therapeutics, Inc. J.N.S. was an employee of Paratek Pharmaceuticals, Inc., at the time the analyses were conducted and is currently an employee of Scientific and Medical Affairs Consulting, LLC. E.T. was an employee of Paratek Pharmaceuticals, Inc., at the time the analyses were conducted and is currently an employee of Neuraptive Therapeutics, Inc.

Background and objective: Sub-therapeutic dosing of piperacillin-tazobactam in critically-ill patients is associated with poor clinical outcomes and may promote the emergence of drug-resistant infections. In this paper, an in silico investigation of whether closed-loop control can improve pharmacokinetic-pharmacodynamic (PK-PD) target attainment is described.Method: An in silico platform was developed using PK data from 20 critically-ill patients receiving piperacillin-tazobactam where serum and tissue interstitial fluid (ISF) PK were defined. Intra-day variability on renal clearance, ISF sensor error, and infusion constraints were taken into account. Proportional-integral-derivative (PID) control was selected for drug delivery modulation. Dose adjustment was made based on ISF sensor data with a 30-min sampling period, targeting a serum piperacillin concentration between 32 and 64 mg/L. A single tuning parameter set was employed across the virtual population. The PID controller was compared to standard therapy, including bolus and continuous infusion of piperacillin-tazobactam.Results: Despite significant inter-subject and simulated intra-day PK variability and sensor error, PID demonstrated a significant improvement in target attainment compared to traditional bolus and continuous infusion approaches.Conclusion: A PID controller driven by ISF drug concentration measurements has the potential to precisely deliver piperacillin-tazobactam in critically-ill patients undergoing treatment for sepsis.

Midazolam (MDZ) is a short-acting benzodiazepine that is widely used to induce and maintain general anesthesia during diagnostic and therapeutic procedures in pediatric patients due to its sedative properties. The aim of this study was to perform a systematic review without a meta-analysis to identify scientific articles and clinical assays concerning MDZ-induced sedation for a pediatric surgery approach. One hundred and twenty-eight results were obtained. After critical reading, 37 articles were eliminated, yielding 91 publications. Additional items were identified, and the final review was performed with a total of 106 publications. In conclusion, to use MDZ accurately, individual patient characteristics, the base disease state, comorbidities, the treatment burden and other drugs with possible pharmacological interactions or adverse reactions must be considered to avoid direct alterations in the pharmacokinetics and pharmacodynamics of MDZ to obtain the desired effects and avoid overdosing in the pediatric population. [ABSTRACT FROM AUTHOR]

The search for new drugs is an extremely time-consuming and expensive endeavour. Much of that time and money go into generating predictive human pharmacokinetic profiles from preclinical efficacy and safety animal data. These pharmacokinetic profiles are used to prioritize or minimize the attrition at later stages of the drug discovery process. In the area of antiviral drug research, these pharmacokinetic profiles are equally important for the optimization, estimation of half-life, determination of effective dose, and dosing regimen, in humans. In this article we have highlighted three important aspects of these profiles. First, the impact of plasma protein binding on two primary pharmacokinetic parameters—volume of distribution and clearance. Second, interdependence of primary parameters on unbound fraction of the drug. Third, the ability to extrapolate human pharmacokinetic parameters and concentration time profiles from animal profiles.

Beta-lactam antibiotics remain one of the most preferred groups of antibiotics in critical care due to their excellent safety profiles and their activity against a wide spectrum of pathogens. The cornerstone of appropriate therapy with beta-lactams is to achieve an adequate plasmatic concentration of a given antibiotic, which is derived primarily from the minimum inhibitory concentration (MIC) of the specific pathogen. In a critically ill patient, the plasmatic levels of drugs could be affected by many significant changes in the patient’s physiology, such as hypoalbuminemia, endothelial dysfunction with the leakage of intravascular fluid into interstitial space and acute kidney injury. Predicting antibiotic concentration from models based on non-critically ill populations may be misleading. Therapeutic drug monitoring (TDM) has been shown to be effective in achieving adequate concentrations of many drugs, including beta-lactam antibiotics. Reliable methods, such as high-performance liquid chromatography, provide the accurate testing of a wide range of beta-lactam antibiotics. Long turnaround times remain the main drawback limiting their widespread use, although progress has been made recently in the implementation of different novel methods of antibiotic testing. However, whether the TDM approach can effectively improve clinically relevant patient outcomes must be proved in future clinical trials.

Aims: Ixekizumab is a high‐affinity monoclonal antibody that selectively targets interleukin‐17A used in the treatment of adult and paediatric patients with moderate‐to‐severe psoriasis. This analysis evaluated the pharmacokinetics (PK) of ixekizumab and the exposure–efficacy relationship in paediatric patients aged 6 to <18 years with psoriasis. Methods: Population PK and exposure–efficacy models were developed. The models used data from paediatric patients with psoriasis participating in the Phase 3 IXORA‐PEDS trial in which patients were dosed according to weight categories. The exposure–efficacy model is a Psoriasis Area and Severity Index (PASI) time course model using data up to Week 12, a co‐primary efficacy endpoint. Results: A 2‐compartment population PK model describes the PK of ixekizumab in paediatric patients with the effect of body weight incorporated on clearance and volume terms using an allometric relationship. The weight category‐based dosing ensured that ixekizumab mean trough serum concentrations in paediatric patients with psoriasis (3.20–3.33 μg/mL) were within the range of concentrations observed in adult patients with psoriasis (mean [standard deviation]: 3.48 [2.16] μg/mL) administered an efficacious dosing regimen. The observed PASI response rates at Week 12 in paediatric patients (91.9/81.8/52.5% for PASI75/90/100) are well predicted by the final exposure–efficacy model and response rates are similar or higher than those achieved in adults (86.2/66.6/35.0% for PASI75/90/100). Conclusion: This analysis is the first to describe the PK and exposure–efficacy relationship of ixekizumab in paediatric patients with psoriasis. The analyses support the selection of the weight category‐based ixekizumab dosing regimens approved for use in paediatric patients with psoriasis. [ABSTRACT FROM AUTHOR]

Background: Profound neuromuscular block (NMB) is important in surgeries where complete immobility is considered essential to improve tracheal intubation and surgical conditions. Rocuronium bromide is a commonly used NMB agent. This work describes a noninvasive approach for estimation of post-tetanic count (PTC) based on two pharmacokinetic (PK) models, the Saldien and the De Haes models. The aim was to investigate the rocuronium bromide PK-pharmacodynamic (PD) relationship in estimating the PTC effect during profound NMB.Methods: In this prospective, non-randomised, observational study, an induction bolus of rocuronium bromide was administered followed by continuous infusion for maintenance of a PTC of 1-2. measured every 3 min. Measurements were analysed as discrete categorical data and by applying the nonlinear mixed-effect modelling approach. Performance of the selected models was evaluated through simulation model-based diagnostics, further assessing the precision of the parameter estimates and the performance of the models at the individual level.Results: Data from 30 adult patients undergoing elective abdominal or neurosurgical procedures were included. Post-tetanic count response profiles during rocuronium bromide infusion were successfully characterised using the population PD analysis. The models showed a good performance for all PTC categories, albeit with a moderate over-prediction of PTC >6.Conclusions: Our findings indicate that using plasma concentrations of rocuronium bromide estimated with either of the two models, combined with a PD model, provides equal model performance when predicting PTC. These promising results may provide an important advance in guiding rocuronium bromide administration when profound NMB in routine clinical practice is desired. [ABSTRACT FROM AUTHOR]

Introduction: The prevalence of obesity is increasing globally. The principal aim was to evaluate whether gastric bypass surgery modifies the bioavailability and pharmacokinetic (PK) parameters of omeprazole. Methods: Controlled, open-label, bioavailability clinical trial in patients undergoing Roux-en-Y gastric bypass (RYGB). Healthy patients with obesity (body mass index >35) were included and assessed for omeprazole PKs before and after RYGB (1 and 6 months). PK sampling was done at baseline and several times up to 12 h after drug dosing. Pre- and post-surgery parameters were compared using paired ANOVA or Wilcoxon tests, and control versus cases using ANOVA or Mann-Whitney tests. Given the post-surgery change in body weight, parameters were corrected by dose/body weight. Results: Fourteen case and 24 control subjects were recruited; 92% were women (N = 35/38). In patients who underwent RYGB, maximum plasma concentration (Cmax) was significantly reduced at 1 and 6 months after surgery compared with presurgery values (p = 0.001). Regarding the AUC, the values are lower at 1 and 6 months after surgery than at baseline (p < 0.001). The drug clearance was also increased in the first month after surgery. No differences were found between patients 6 months after surgery and controls. Cmax and AUC corrected by dose/body weight were significantly different between the baseline surgery subjects and controls. Discusion/Conclusions: Omeprazole bioavailability is reduced in patients with obesity at 1 and 6 months after RYGB. However, omeprazole PK parameters 6 months after RYGB are similar to control subjects, and thus no dose correction is required after RYGB for a given indication. [ABSTRACT FROM AUTHOR]

Tacrolimus (TAC) is a first-choice immunosuppressant for solid organ transplantation, characterized by high potential for drug-drug interactions, significant inter and intrapatient variability, and narrow therapeutic index. Therapeutic drug monitoring (TDM) of TAC concentrations in whole blood (WB) is capable of reducing the incidence of adverse events. Since TAC acts within lymphocytes, its monitoring in peripheral blood mononuclear cells (PBMC) may represent a valid future alternative for TDM. Nevertheless, TAC intracellular concentrations and their variability are poorly described, particularly in the pediatric context. Therefore, our aim was describing TAC concentrations in WB and PBMC and their variability in a cohort of pediatric patients undergoing constant immunosuppressive maintenance therapy, after liver transplantation. TAC intra-PBMCs quantification was performed through a validated UHPLC–MS/MS assay over a period of 2–3 months. There were 27 patients included in this study. No significant TAC changes in intracellular concentrations were observed (p = 0.710), with a median percent change of −0.1% (IQR −22.4%–+46.9%) between timings: this intra-individual variability was similar to the one in WB, −2.9% (IQR −29.4–+42.1; p = 0.902). Among different patients, TAC weight-adjusted dose and age appeared to be significant predictors of TAC concentrations in WB and PBMC. Intra-individual seasonal variation of TAC concentrations in WB, but not in PBMC, have been observed. These data show that the intra-individual variability in TAC intracellular exposure is comparable to the one observed in WB. This opens the way for further studies aiming at the identification of therapeutic ranges for TAC intra-PBMC concentrations. [ABSTRACT FROM AUTHOR]

Introduction: The prevalence of obesity is increasing globally. The principal aim was to evaluate whether gastric bypass surgery modifies the bioavailability and pharmacokinetic (PK) parameters of omeprazole. Methods: Controlled, open-label, bioavailability clinical trial in patients undergoing Roux-en-Y gastric bypass (RYGB). Healthy patients with obesity (body mass index >35) were included and assessed for omeprazole PKs before and after RYGB (1 and 6 months). PK sampling was done at baseline and several times up to 12 h after drug dosing. Pre- and post-surgery parameters were compared using paired ANOVA or Wilcoxon tests, and control versus cases using ANOVA or Mann-Whitney tests. Given the post-surgery change in body weight, parameters were corrected by dose/body weight. Results: Fourteen case and 24 control subjects were recruited; 92% were women (N = 35/38). In patients who underwent RYGB, maximum plasma concentration (Cmax) was significantly reduced at 1 and 6 months after surgery compared with presurgery values (p = 0.001). Regarding the AUC, the values are lower at 1 and 6 months after surgery than at baseline (p < 0.001). The drug clearance was also increased in the first month after surgery. No differences were found between patients 6 months after surgery and controls. Cmax and AUC corrected by dose/body weight were significantly different between the baseline surgery subjects and controls. Discusion/Conclusions: Omeprazole bioavailability is reduced in patients with obesity at 1 and 6 months after RYGB. However, omeprazole PK parameters 6 months after RYGB are similar to control subjects, and thus no dose correction is required after RYGB for a given indication.

Tacrolimus (TAC) is a first-choice immunosuppressant for solid organ transplantation, characterized by high potential for drug-drug interactions, significant inter- and intra-patient variability, and narrow therapeutic index. Therapeutic drug monitoring (TDM) of TAC concentrations in whole blood (WB) is capable of reducing the incidence of adverse events. Since TAC acts within lymphocytes, its monitoring in peripheral blood mononuclear cells (PBMC) may represent a valid future alternative for TDM. Nevertheless, TAC intracellular concentrations and their variability are poorly described, particularly in the pediatric context. Therefore, our aim was describing TAC concentrations in WB and PBMC and their variability in a cohort of pediatric patients undergoing constant immunosuppressive maintenance therapy, after liver transplantation. TAC intra-PBMCs quantification was performed through a validated UHPLC–MS/MS assay over a period of 2–3 months. There were 27 patients included in this study. No significant TAC changes in intracellular concentrations were observed (p = 0.710), with a median percent change of −0.1% (IQR −22.4%–+46.9%) between timings: this intra-individual variability was similar to the one in WB, −2.9% (IQR −29.4–+42.1; p = 0.902). Among different patients, TAC weight-adjusted dose and age appeared to be significant predictors of TAC concentrations in WB and PBMC. Intra-individual seasonal variation of TAC concentrations in WB, but not in PBMC, have been observed. These data show that the intra-individual variability in TAC intracellular exposure is comparable to the one observed in WB. This opens the way for further studies aiming at the identification of therapeutic ranges for TAC intra-PBMC concentrations.

Aims: Simulations are an essential tool for investigating scenarios in pharmacokinetics‐pharmacodynamics. The models used during simulation often include the effect of highly correlated covariates such as weight, height and sex, and for children also age, which complicates the construction of an in silico population. For this reason, a suitable and representative patient population is crucial for the simulations to produce meaningful results. For simulation in paediatric patients, international growth charts from the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) provide a reference, but these may not always be representative for specific populations, such as malnourished children with HIV or acutely unwell children. Methods: We present a workflow to construct a virtual paediatric patient population using WHO and CDC growth charts, suggest piecewise linear functions to adjust the median of the growth charts by sex and age, and suggest visual diagnostics to compare with the target population. We applied this workflow in a population of 1206 HIV‐positive African children, consisting of 19 742 observations with weight ranging from 3.8 to 79.7 kg, height from 55.5 to 180 cm, and an age between 0.40 and 18 years. Results: Before adjustment, the WHO and CDC charts produced weights and heights higher compared to the observed data. After applying our methodology, we could simulate weight, height, sex and age combinations in good agreement with the observed data. Conclusion: The methodology presented here is flexible and may be applied to other scenarios where WHO and CDC growth standards might not be appropriate. In addition we provide R scripts and a large ready‐to‐use paediatric population. [ABSTRACT FROM AUTHOR]

Aims: To characterize relationships between apolipoprotein A‐I (apoA‐I) exposure and cholesterol efflux capacity (CEC) and covariate effects following CSL112 (apoA‐I [human]) administration in an integrated population including acute myocardial infarction (AMI) patients. Methods: A pharmacometric analysis utilized data from seven clinical trials, including patients with AMI, subjects with renal impairment and healthy subjects. A population pharmacokinetic (PK) analysis was performed to relate CSL112 doses to changes in apoA‐I plasma concentrations. Covariate analysis was conducted to identify sources of variability in apoA‐I exposure. Exposure‐response modeling was conducted to describe the relationship between apoA‐I exposure and total or ATP binding cassette transporter A1‐(ABCA1)‐dependent CEC and to identify clinical predictors of CEC. Results: A two‐compartment model described apoA‐I PK. ApoA‐I clearance was slightly lower in subjects with AMI, whereas baseline apoA‐I was marginally higher in female and Japanese subjects. Covariate effects on apoA‐I exposure were in the order of 10% and thus not clinically relevant. The relationships between apoA‐I exposure and CECs were described by nonlinear models. Simulations showed CEC elevation resulting from apoA‐I exposure increment was comparable in AMI and non‐AMI subjects; no covariate had clinically meaningful effects on CEC. Simulations also demonstrated that CEC in patients with AMI post 6 g CSL112 dosing was substantially elevated compared to placebo and lower dose levels. Conclusions: The model‐based exposure‐response analysis demonstrated, irrespective of body weight, sex and race, that fixed 6 g CSL112 dosing causes a desired CEC elevation, which may benefit AMI patients by potentially reducing early recurrent cardiovascular event risk. [ABSTRACT FROM AUTHOR]

Dose selection and optimization is an important topic in drug development to maximize treatment benefits for all patients. While exposure–response (E‐R) analysis is a useful method to inform dose‐selection strategy, in oncology, special considerations for prognostic factors are needed due to their potential to confound the E‐R analysis for monoclonal antibodies. The current review focuses on 3 different approaches to mitigate the confounding effects for monoclonal antibodies in oncology: (i) Cox‐proportional hazards modelling and case‐matching; (ii) tumour growth inhibition–overall survival modelling; and (iii) multiple dose level study design. In the presence of confounding effects, studying multiple dose levels may be required to reveal the true E‐R relationship. However, it is impractical for pivotal trials in oncology drug development programmes. Therefore, the strengths and weaknesses of the other 2 approaches are considered, and the favourable utility of tumour growth inhibition–overall survival modelling to address confounding in E‐R analyses is described. In the broader scope of oncology drug development, this review discusses the downfall of the current emphasis on E‐R analyses using data from single dose level trials and proposes that development programmes be designed to study more dose levels in earlier trials. [ABSTRACT FROM AUTHOR]

Chimeric antigen receptor (CAR) T-cell therapy is an immunotherapy that has recently become highly instrumental in the fight against life-threatening diseases. A variety of modeling and computational simulation efforts have addressed different aspects of CAR T-cell therapy, including T-cell activation, T- and malignant cell population dynamics, therapeutic cost-effectiveness strategies, and patient survival. In this article, we present a systematic review of those efforts, including mathematical, statistical, and stochastic models employing a wide range of algorithms, from differential equations to machine learning. To the best of our knowledge, this is the first review of all such models studying CAR T-cell therapy. In this review, we provide a detailed summary of the strengths, limitations, methodology, data used, and data gap in currently published models. This information may help in designing and building better models for enhanced prediction and assessment of the benefit-risk balance associated with novel CAR T-cell therapies, as well as with the data need for building such models. [ABSTRACT FROM AUTHOR]

Omadacycline (PTK-0796) is a first-in-class aminomethylcycline for adult patients with community-acquired bacterial pneumonia (CABP) and acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible pathogens. We investigated the pharmacokinetic (PK) and pharmacodynamic (PD) profile of omadacycline, considering the impact of covariates, particularly ethnicity, on PK and determined the PK/PD cutoff values for dosing regimens. Utilizing nonlinear mixed-effects modeling, we pooled data from 11 clinical trials for PopPK analysis. The first-order conditional estimation with interaction (FOCEI) method in NONMEM facilitated model parameter estimation. Employing a stepwise model selection strategy, with forward addition (P < 0.01) and backward deletion (P < 0.001), we assessed the potential impacts of covariates on omadacycline PK, including baseline age, body weight, sex, race, body mass index, body surface area, baseline albumin, creatine clearance, and formulation. After validating the model through various methods, the final PopPK model underwent Monte Carlo simulations to generate the PK profile for the Chinese population. This enabled AUC calculation and assessment of the probability of target attainment (PTA) and the cumulative fraction of response (CFR) for various dosing regimens and bacterial strains. Omadacycline's PK can be adequately characterized by a three-compartment model. Body weight, sex, race, and drug formulation statistically influenced its PK. Asians and non-Asians exhibit similar exposure after intravenous infusion, but oral dosing results in much higher exposures than in non-Asians. Monte Carlo simulation indicates that IV-only or IV/PO sequential therapy regimens provide adequate attainment for all major pathogens causing ABSSSI and CABP. PK/PD cutoffs were generally above the MIC 90 value of recent clinical isolates from China. In conclusion, the approved regimen for China achieved adequate target attainment for all pathogens typically associated with these infections. The higher oral exposure observed in Asians may enhance efficacy without affecting safety or tolerability. [Display omitted] [ABSTRACT FROM AUTHOR]

Unforeseen surfacing of microbial keratitis (MKT) over the years has led to a requisite for promising treatment strategy involving combination of antifungal and antibacterial agents. Subsequently, symptoms associated with MKT including inflammation and watery eyes require treatment with anti-inflammatory agents. Thus, a requirement of functional clinical treatment strategy involving combination of anti-inflammatory corticosteroids (Betamethasone) with antifungal polyene (Amphotericin B, AmB) and antibacterials macrolide (Azithromycin, AZT) and aminoglycoside (Neomycin, NEO). In the ensuing pursuit, a sensitive and fast simultaneous LC-MS/MS method of four drastically different analytes in rabbit tear fluid and cornea was developed and validated as per US-FDA guidelines. The gradient LC set-up was used with C18 column and flow rate of 0.55 mL/min along with short run time of 7 min. The calibration curves showed good linearity over the concentration range of 0.07–300 ng/mL, 1.00–400 ng/mL, 3.00–600 ng/mL and 8.00–900 ng/mL for AZT, AmB, NEO and BEM respectively. The bioanalytical method requires only 10 µL of ocular sample and analytes were extracted with fast protein precipitation with acidic methanol. Finally, the developed method was validated for selectivity, linearity (r2 > 0.99), precision, accuracy, matrix effects, and stability. PK-PD indices and dosing frequency was predicted using Phoenix WinNonlin Software, based on single dose ocular pharmacokinetics and MIC values of AmB, AZT and NEO. According to the PK-PD simulation, S. aureus and E. coli required 6 and 12 instillations of AZT per 24 h, respectively whereas 12 instillation of NEO requires per 24 h for S. aureus. The result suggests that to minimize antimicrobial resistance; drug, dose and dosing schedule depend upon the pathogen as well as the strain. • Simultaneous LCMS/MS method of corticosteroids, polyene, macrolide and aminoglycoside. • Bioanalytical method validation of antibiotics in ocular biofluids and cornea. • Prediction of dosage regimen by single dose ocular PK study and MIC values. • Dose and dosage regimen depends upon the pathogen as well as strain. • Appropriate dose and dosing schedule minimizes the drug resistance. [ABSTRACT FROM AUTHOR]

ABSTRACT The severity of diseases, the complexity of treatment, and the use of medical devices in the intensive care unit (ICU) may change the pharmacokinetics (PK) profile of antibiotics among critically ill patients.This narrative review aims to explain the PK profile of critically ill patients compared to other group of patients and to describe the pharmacokinetic-pharmacidynamic (PK-PD) target attainment among this group of patients. Only articles published less than 10 years ago were included in this narrative review. Evidences have indicated that critically ill patients have relatively larger volume distribution (Vd) of hydrophilic antibiotics compared to patients with stable conditions. The fluid shifting to interstitial space, hypoalbuminemia, and aggressive fluid treatment may contribute to the increase value of Vd in critically ill patients. The clearance (CL) of hydrophilic antibiotics in critically ill patients is highly determined by dynamic changing of renal function compared to patients in other wards. The phenomenon of augmented renal clearance and the use of high intensity of renal replacement therapy can increase the CL of hydrophilic antibiotics. The different PK profile of antibiotics may lead to the failure of attaining the PK-PD target if the dose of antibiotics is not adjusted according to such differences. ABSTRAK Tingkat keparahan penyakit yang relatif tinggi dibandingkan pasien di bangsal rawat lain dan penggunaan terapi serta alat medis yang relatif lebih kompleks di ruang intensive care unit (ICU) dapat berdampak pada perubahan profil farmakokinetik (PK) antibiotik pada pasien kritis. Tujuan utama kajian naratif ini adalah untuk memaparkan profil PK dan ketercapaian target farmakokinetik-farmakodinamik (PK-PD) pasien kritis di ICU. Hanya artikel yang diterbitkan dalam kurun waktu 10 tahun terakhir yang digunakan dalam kajian naratif ini. Bukti penelitian menunjukkan bahwa volume distribusi (Vd) antibiotik hidrofilik pada pasien kritis lebih besar dibandingkan dengan pasien yang relatif lebih stabil atau subyek sehat. Perpindahan cairan intravaskuler ke daerah interstitial, hipoalbuminemia, dan terapi cairan khususnya yang diberikan secara agresif merupakan faktor yang berkontribusi terhadap peningkatan Vd pada pasien kritis. Clearance (CL) antibiotik hidrofilik pada pasien kritis ditentukan oleh perubahan fungsi ginjal yang relatif lebih dinamis dibandingkan dengan pasien di ruang rawat inap lain. Fenomena augmented renal clearance yang umum dijumpai pada pasien kritis dan penggunaan renal replacement therapy dengan intensitas yang tinggi dapat meningkatkan CL antibiotik hidrofilik. Perbedaan profil PK tersebut berpotensi menyebabkan kegagalan untuk mencapai target PK-PD apabila tidak dilakukan penyesuaian dosis antibiotik pada pasien kritis. Identifikasi profil PK perlu diupayakan sebagai langkah awal untuk mengoptimalkan pemberian antibiotik pada kelompok pasien kritis.

Abstract This study sought to investigate whether dosing frequency (the number of doses per day) affects the antimicrobial efficacy and safety of ampicillin/sulbactam (ABPC/SBT) in Japanese elderly pneumonia patients treated with ABPC/SBT at 6 g/day. This was a retrospective observational study that included hospitalized elderly patients (aged ≥75 years, 10 ml/min ≤CLcr

This study sought to investigate whether dosing frequency (the number of doses per day) affects the antimicrobial efficacy and safety of ampicillin/sulbactam (ABPC/SBT) in Japanese elderly pneumonia patients treated with ABPC/SBT at 6 g/day. This was a retrospective observational study that included hospitalized elderly patients (aged ≥75 years, 10 ml/min ≤CLcr <50 ml/min) who received 3 g every 12 h (BID; n = 61) or 1.5 g every 6 h (QID; n = 45) for the treatment of pneumonia. The primary endpoint was clinical response, assessed by measuring body temperature, white blood cell count, and C-reactive protein levels. Pharmacokinetic and pharmacodynamic simulations were conducted in silico to rationalize the clinicalfindings. The clinicalresponse rates (extremely effective and effective) in the BID and QID groups were 36.1% and 55.6%, respectively (p = .0459). QID tended to be more effective in patients with gram-negative rods detected (p = .0563). According to the simulated minimum plasmaABPCconcentrations at steady state for BID and QID were 2.5 and 7.3 μg/ml, respectively (p < .0001). Based on the simulated time above minimum inhibitory concentration (MIC), pharmacological (not clinical) efficacy was predicted to be higher with QID. Both groups had similar safety profiles. The main adverse event in both groups was liver damage. The present retrospective survey demonstrated that ABPC/SBT treatment for elderly patients with pneumonia and renal dysfunction was more effective with QID than with BID. Therefore,the QID regimen is worthy of consideration to improve the clinical outcomes of ABPC/SBT therapy in the present patient population. [ABSTRACT FROM AUTHOR]

Purpose of Review: Clinicians should be encouraged to use pharmacokinetic-pharmacodynamic (PK-PD) studies to optimize antifungal drug dosing in the absence of robust comparative effectiveness data or in cases where evidence of causality has not yet been firmly established. The purpose of this article is to review how new triazole and echinocandin PK-PD studies have contributed to our current understanding of antifungal selection and dose optimization against invasive fungal infections. Emerging infections such as C. auris and novel antifungal drugs such as rezafungin will also be highlighted. Future research endeavors are suggested where currently robust clinical outcomes data associated with PK-PD target attainment are lacking. Recent Findings: Recent results from clinical fluconazole PK-PD studies may indicate that unique AUC24/MIC thresholds exist for specific Candida species. The inability of recent studies to confirm previous fluconazole AUC24/MIC clinical PK-PD targets of 11 to 400 may also be due to previously unrecognized PK variability in special patient populations such as those with augmented renal clearance. A free AUC24/MIC threshold of 25 appears to be conserved across the azole antifungal class in animal models of invasive candidiasis. Current therapeutic drug monitoring guidance with voriconazole, posaconazole, and itraconazole has been used to indirectly confirm pre-clinical AUC24/MIC PK-PD targets in invasive candidiasis and aspergillosis. Elucidation of the PK-PD targets in pre-clinical models has led to successful isavuconazole dose optimization in human studies and has contributed to dosing recommendations for the novel echinocandin rezafungin. PK-PD research will also be important in guiding antifungal selection against infections caused by emerging pathogens, such as Candida auris, and those caused by fungi for which reduced susceptibility is a growing concern, including Coccidioides species and azole-resistant Aspergillus fumigatus. Summary: PK-PD research may be used to inform treatment decisions for rare fungal infections, infections with rapidly changing epidemiology, in patient populations expected to have altered pharmacokinetics, for novel antifungal drugs or those with new formulations, and in cases where evidence of causality cannot be established from large randomized comparative studies. A number of animal models have been developed and more clinical PK-PD studies are being conducted. In the absence of clinical PK-PD outcome data in human studies, researchers have expanded the use of currently available therapeutic drug monitoring to gain insight into possible PK-PD targets. [ABSTRACT FROM AUTHOR]

Aims and objectives: Vancomycin is a drug of choice for various gram-positive bacterial (GPB) infections and is largely prescribed to pediatric intensive care unit (PICU) patients. Despite the different pathophysiology of these patients, limited data are available on pharmacokinetics of vancomycin. There are lack of data for critically ill Indian children; hence, study was conducted to assess the steady-state pharmacokinetics in children admitted to PICU. Materials and methods: Twelve subjects (seven males, five females) aged 1-12 years were enrolled. Vancomycin (dose of 20 mg/kg per 8 hours) was infused for over 1 hour and steady-state pharmacokinetics was performed on day 3. Vancomycin concentrations were measured by the validated liquid chromatography mass spectrometry method. Pharmacokinetic parameters were calculated using Winnonlin (Version 6.3; Pharsight, St. Louis, MO). Results: The steady-state mean ... was 40.94 μg/mL (±15.07), and mean AUC0-8 hours was 124.15 μg/mL (±51.27). The mean t1/2 was 4.82 hours (±2.71), Vd was 12.48 L (±4.43), and Cl was 2.08 mL/minute (±0.89). The mean AUC0-24 among 12 subjects was 372.44 μg/mL (±153.82). Among 35 measured trough concentrations, 23 (65.71%) were below, 11 (31.43%) were within, and 1 (2.86%) was above the recommended range. Conclusion: The pharmacokinetic parameters of vancomycin were comparable with previously reported studies. However, recommended trough levels (10-20 μg/mL) were not achievable with current recommended dosing of 60 mg/kg/day. [ABSTRACT FROM AUTHOR]

Rationale: Vancomycin remains the standard of care for gram-positive bacterial infections, though there are significant developments in newer antibacterial agents. Efficacy can be improved by linking pharmacokinetic with pharmacodynamic principles, thus leading to optimum antibiotic exposure. There is scarcity of pharmacokinetic data in Indian intensive care unit (ICU) population. Materials and methods: Fifteen subjects with suspected or proven gram-positive bacterial infection of either gender between 18 years and 65 years of age were enrolled. Vancomycin at the dose of 1 g every 12 hours was administered over 1-hour period and pharmacokinetic assessments performed on blood samples collected on days 1 and 3. Vancomycin concentrations were measured on validated liquid chromatography mass spectrometry method. Pharmacokinetic parameters were calculated using Winnonlin (Version 6.3; Pharsight, St. Louis, MO). Results: The mean Cmax, elimination half-life, AUC0-12hours, volume of distribution, and clearance of single dose were 36.46 μg/mL (±14.87), 3.98 hours (±1.31), 113.51 μg/mL (±49.51), 52.01 L (±31.31), and 8.90 mL/minute (±3.29), respectively, and at steady state were 40.87 μg/mL (±19.29), 6.27 hours (±3.39), 147.94 μg/mL (±72.89), 56.39 L (±42.13), and 6.98 mL/minute (±4.48), respectively. The elimination half-life increased almost two-fold at steady state. The steady state mean AUC0--24 was 295.89 µg/mL (±153.82). Out of 45 trough levels, 32 (71.11%) concentrations were below recommended range. Conclusion: Recommended AUC0--24hours and trough concentrations were not achieved in majority of patients with current dosing, suggesting reevaluation of current vancomycin dosing. Individualized treatment based on close monitoring of vancomycin serum concentrations in critically ill patients is imperative. [ABSTRACT FROM AUTHOR]

Dalbavancin is a lipoglycopeptide approved for treatment of Gram-positive infections of skin and skin-associated structures (ABSSSI). Currently, off-label use at high dosages for osteoarticular infections deserves attention. This work aimed to study the long-term plasma pharmacokinetics of dalbavancin in outpatients with ABSSSI or osteoarticular infections, treated either with one or two 1500 mg doses of dalbavancin. A liquid chromatography-tandem mass spectrometry method was used to measure total dalbavancin concentrations in plasma samples. The results were analyzed through a non-compartmental analysis (NCA). Breakpoint minimum inhibitory concentration (MIC) was used to calculate AUC/MIC and T > MIC parameters, adjusted by 93% protein binding. A total of 14 patients were enrolled, 11 with osteoarticular infection and 3 with ABSSSI. Long-term pharmacokinetics showed median T > MIC (0.125 mg/L) of 11.9 and 13.7 weeks for single and dual dose, respectively. Similarly, median AUC0-2w/MIC ratios of 20,590 and 31,366 were observed for single and dual dose regimens, respectively. No adverse events were observed, and treatment success was achieved in 12/14 patients. Failure was associated with the worst clinical conditions, bone infections, and single dose. The results of this study show that dalbavancin exposure exceeds previously suggested pharmacodynamic targets. Optimization of these targets is needed for the osteoarticular setting.

Ustekinumab is a monoclonal antibody used in Crohn’s disease (CD). Dose optimization in case of non-response and the role of pharmacokinetic–pharmacodynamic (PK-PD) monitoring remain unresolved dilemmas in clinical practice. We aimed to develop a population PK-PD model for ustekinumab in CD and simulate efficacy of alternative dosing regimens. We included 57 patients and recorded their characteristics during 32 weeks after starting with ustekinumab therapy. Serum ustekinumab concentration was prospectively measured and fecal calprotectin (FC) concentration was used to monitor the disease activity. Ustekinumab PK-PD was described by a two-compartment target-mediated drug disposition model linked to an indirect response model. Lower fat-free mass, higher serum albumin, previous non-exposure to biologics, FCGR3A-158 V/V variant and lower C-reactive protein were associated with higher ustekinumab exposure. Model-based simulation suggested that 41.9% of patients receiving standard dosing achieve biochemical remission at week 32. In patients not achieving remission with standard dosing at week 16, transition to 4-weekly subcutaneous maintenance dosing with or without intravenous reinduction resulted in comparably higher remission rates at week 32 (51.1% vs. 49.2%, respectively). Our findings could be used to guide stratified ustekinumab treatment in CD, particularly in patients with unfavorable characteristics, who might benefit from early transition to 4-weekly maintenance dosing.

Abstract Despite intensive treatments including temozolomide (TMZ) administration, glioblastoma patient prognosis remains dismal and innovative therapeutic strategies are urgently needed. A systems pharmacology approach was undertaken to investigate TMZ pharmacokinetics‐pharmacodynamics (PK‐PD) incorporating the effect of local pH, tumor spatial configuration and micro‐environment. A hybrid mathematical framework was designed coupling ordinary differential equations describing the intracellular reactions, with a spatial cellular automaton to individualize the cells. A differential drug impact on tumor and healthy cells at constant extracellular pH was computationally demonstrated as TMZ‐induced DNA damage was larger in tumor cells as compared to normal cells due to less acidic intracellular pH in cancer cells. Optimality of TMZ efficacy defined as maximum difference between damage in tumor and healthy cells was reached for extracellular pH between 6.8 and 7.5. Next, TMZ PK‐PD in a solid tumor was demonstrated to highly depend on its spatial configuration as spread cancer cells or fragmented tumors presented higher TMZ‐induced damage as compared to compact tumor spheroid. Simulations highlighted that smaller tumors were less acidic than bigger ones allowing for faster TMZ activation and their closer distance to blood capillaries allowed for better drug penetration. For model parameters corresponding to U87 glioma cells, inter‐cell variability in TMZ uptake play no role regarding the mean drug‐induced damage in the whole cell population whereas this quantity was increased by inter‐cell variability in TMZ efflux which was thus a disadvantage in terms of drug resistance. Overall, this study revealed pH as a new potential target to significantly improve TMZ antitumor efficacy.

Background/aim: Osimertinib blood levels and their impact on treatment continuation in patients with EGFR mutation-positive lung cancer is not known. This study investigated the drug blood levels and risk factors affecting treatment continuation., Patients and Methods: Fifty-six patients with recurrent and inoperable epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer who received Osimertinib (80 mg once daily, daily dose) between October 1, 2016, and August 31, 2021, were included. Patients were classified into two groups using a cutoff blood level of 155 ng/ml. The primary endpoint was the relationship between Osimertinib exposure and efficacy, and secondary endpoints were the relationship between Osimertinib exposure and side effects, and the effect of covariates on efficacy and blood levels., Results: The median progression-free survival (PFS) for evaluable patients in the steady-state trough concentration (C min ss ) ≥155 ng/ml and C min ss <155 ng/ml groups was 18.7 months and 31.2 months. Serum albumin (Alb) levels were 3.73±0.40 g/dl and 3.93±0.28 g/dl (p=0.030), respectively, and in multivariate analysis, Alb <3.7 g/dl was associated with a hazard ratio of 5.304 (95%CI=1.431-19.66; p=0.013), indicating that Alb <3.7 g/dl significantly shortened PFS., Conclusion: Free blood concentration of Osimertinib may have been increased by a combination of factors, including decreased hepatic metabolic function and decreased albumin production caused by systemic inflammation in patients with cancer. However, there was no effect of Osimertinib C min ss on PFS., (Copyright © 2023, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

The aims of this study were to evaluate the pharmacokinetics of doripenem (Finibax®, Doribax®, S-4661), a parenteral carbapenem antibiotic, in pediatric patients based on concentrations of doripenem in plasma after administration of 20 mg/kg 2 or 3 times daily and to evaluate the dosing regimens by using Monte-Carlo pharmacokinetic-pharmacodynamic simulations. Population pharmacokinetic analysis was performed by using 190 plasma concentrations of doripenem from 99 patients (2 months-13 years old). The two-compartment model well described the doripenem plasma concentrations in pediatric patients. Body weight was found to be the most significant influential factor. Gender was also found to be a significant covariate although the effect was relatively small. Monte-Carlo simulations indicated that 20 mg/kg over 1 h infusion would give 90% probability of target attainment for 40% of time above minimum inhibitory concentration against Haemophilus influenzae and Streptococcus pneumoniae , major causative pathogens in pediatric infections, and that 40 mg/kg, the highest approved dose for Japanese pediatric patients, administered over 3 h infusion achieved 98.6% against 8 μg/mL. The developed population pharmacokinetic model of doripenem and Monte-Carlo simulations for pediatric patients should provide useful information for understanding the pharmacokinetic and pharmacokinetic-pharmacodynamic characteristics of doripenem and for optimal treatment of pediatric patients. [ABSTRACT FROM AUTHOR]

Highlights • The population PK-PD of latamoxef in neonates and young infants was evaluated and an evidence-based dosing regimen was established. • Current body weight, birth weight, and postnatal age were identified as significant covariates influencing latamoxef clearance. • The current dosing regimen (30 mg/kg q12h) is effective against Escherichia coli and Klebsiella pneurnoniae (MIC ≤ 1 mg/L). • A higher dose regimen of 30 mg/kg q8h were required against Staphylococcus aureus (MIC = 4 mg/L). Abstract Objectives There has been recent renewed interest in historical antibiotics because of the increased antibiotic-resistant bacterial strains. Latamoxef, a semi-synthetic oxacephem antibiotic developed in 1980s, has recently been brought back into use for treatment of infections in newborns; however, it is still used off-label in neonatal clinical practice due to the lack of an evidence-based dosing regimen. This study was performed to evaluate the pharmacokinetics of latamoxef in neonates and young infants, and to provide an evidence-based dosing regimen for newborns based on developmental pharmacokinetics-pharmacodynamics (PK-PD). Methods Opportunistic blood samples from newborns treated with latamoxef were collected to determine the latamoxef concentration by high-performance liquid chromatography with UV detection. Population PK-PD analysis was conducted using NONMEM and R software. A total of 165 plasma samples from 128 newborns (postmenstrual age range 28.4–46.1 weeks) were available for analysis. Results A two-compartment model with first-order elimination showed the best fit with the data. Current body weight, birth weight, and postnatal age were identified as significant covariates influencing latamoxef clearance. Simulation indicated that the current dosing regimen (30 mg/kg q12h) is adequate with an MIC of 1 mg/L. For an MIC of 4 mg/L, 30 mg/kg q8h was required to achieve a target rate of 70% of patients having a free antimicrobial drug concentration exceeding the MIC during 70% of the dosing interval. Conclusions Based on the developmental PK-PD analysis of latamoxef, a rational dosing regimen of 30 mg/kg q12h or q8h was required in newborns, depending on the pathogen. [ABSTRACT FROM AUTHOR]

Despite intensive treatments including temozolomide (TMZ) administration, glioblastoma patient prognosis remains dismal and innovative therapeutic strategies are urgently needed. A systems pharmacology approach was undertaken to investigate TMZ pharmacokinetics‐pharmacodynamics (PK‐PD) incorporating the effect of local pH, tumor spatial configuration and micro‐environment. A hybrid mathematical framework was designed coupling ordinary differential equations describing the intracellular reactions, with a spatial cellular automaton to individualize the cells. A differential drug impact on tumor and healthy cells at constant extracellular pH was computationally demonstrated as TMZ‐induced DNA damage was larger in tumor cells as compared to normal cells due to less acidic intracellular pH in cancer cells. Optimality of TMZ efficacy defined as maximum difference between damage in tumor and healthy cells was reached for extracellular pH between 6.8 and 7.5. Next, TMZ PK‐PD in a solid tumor was demonstrated to highly depend on its spatial configuration as spread cancer cells or fragmented tumors presented higher TMZ‐induced damage as compared to compact tumor spheroid. Simulations highlighted that smaller tumors were less acidic than bigger ones allowing for faster TMZ activation and their closer distance to blood capillaries allowed for better drug penetration. For model parameters corresponding to U87 glioma cells, inter‐cell variability in TMZ uptake play no role regarding the mean drug‐induced damage in the whole cell population whereas this quantity was increased by inter‐cell variability in TMZ efflux which was thus a disadvantage in terms of drug resistance. Overall, this study revealed pH as a new potential target to significantly improve TMZ antitumor efficacy. [ABSTRACT FROM AUTHOR]

ResuLts of precLinicaL pharmacodynamic and pharmacokinetic study of tropoxine (a new originaL antimigraine drug) after singLe intravenous administration in rats were presented. Tropoxine in significant extent suppresses constricting reactions of rat brain vesseLs, serotonin, and agonist of 5НТ2В/2С receptors. Direct reLationship between tropoxine concentrations decreasing in the rat bLood pLasma and changing of the brain circuLation associated with serotonin and m-chLorphenyLpiperazine.