Comparison of pharmaceutical properties and biological activities of prednisolone, deflazacort, and vamorolone in DMD disease models.

Duchenne muscular dystrophy (DMD) is a progressive disabling X-linked recessive disorder that causes gradual and irreversible loss of muscle, resulting in early death. The corticosteroids prednisone/prednisolone and deflazacort are used to treat DMD as the standard of care; however, only deflazacort is FDA approved for DMD. The novel atypical corticosteroid vamorolone is being investigated for treatment of DMD. We compared the pharmaceutical properties as well as the efficacy and safety of the three corticosteroids across multiple doses in the B10-mdx DMD mouse model. Pharmacokinetic studies in the mouse and evaluation of p-glycoprotein (P-gP) efflux in a cellular system demonstrated that vamorolone is not a strong P-gp substrate resulting in measurable central nervous system (CNS) exposure in the mouse. In contrast, deflazacort and prednisolone are strong P-gp substrates. All three corticosteroids showed efficacy, but also side effects at efficacious doses. After dosing mdx mice for two weeks, all three corticosteroids induced changes in gene expression in the liver and the muscle, but prednisolone and vamorolone induced more changes in the brain than did deflazacort. Both prednisolone and vamorolone induced depression-like behavior. All three corticosteroids reduced endogenous corticosterone levels, increased glucose levels, and reduced osteocalcin levels. Using micro-computed tomography, femur bone density was decreased, reaching significance with prednisolone. The results of these studies indicate that efficacious doses of vamorolone, are associated with similar side effects as seen with other corticosteroids. Further, because vamorolone is not a strong P-gp substrate, vamorolone distributes into the CNS increasing the potential CNS side-effects.

Impact of hypoalbuminemia on clinical outcomes among patients with obesity treated with ceftriaxone.

The use of ceftriaxone, a highly protein-bound drug, in the setting of hypoalbuminemia may result in suboptimal drug exposure. Patients with obesity also exhibit higher absolute drug clearance. We aimed to evaluate the impact of hypoalbuminemia on clinical success among hospitalized adults with obesity who were treated with ceftriaxone. This retrospective review included adult inpatients with weight >100 kg or body mass index >40 kg/m2 who received ceftriaxone 2 g intravenously every 12 hours for at least 72 hours. The primary outcome was clinical success, a composite of clinical cure and microbiologic cure. Secondary outcomes included clinical cure, microbiologic cure, length of stay, ICU length of stay, mortality, 30-day readmission, and adverse events. In all, 137 patients were included, 34 of whom had a serum albumin of ≤2.5 g/dL. In a propensity-score-weighted analysis, clinical success was significantly more common among those without hypoalbuminemia (91.2%) as compared to those with hypoalbuminemia (77.8%) (P = 0.038). Death within 30 days (13.7% vs 0%, P < 0.001) and 30-day readmission (31.6% vs 12.0%, P = 0.008) were more common in the hypoalbuminemia group. In a univariate analysis, serum albumin and indication for ceftriaxone use were found to be predictors of clinical success. Hypoalbuminemia was associated with a lower rate of clinical success among patients with obesity who were treated with ceftriaxone 2 g every 12 hours.

Simulated drug disposition in critically ill patients to evaluate effective PK/PD targets for combating Pseudomonas aeruginosa resistance to meropenem.

Bacterial infections, including those caused by Pseudomonas aeruginosa, often lead to sepsis, necessitating effective antibiotic treatment like carbapenems. The key pharmacokinetic/pharmacodynamic (PK/PD) index correlated to carbapenem efficacy is the fraction time of unbound plasma concentration above the minimum inhibitory concentration (MIC) of the pathogen (%fT > MIC). While multiple targets exist, determining the most effective one for critically ill patients remains a matter of debate. This study evaluated meropenem's bactericidal potency and its ability to combat drug resistance in Pseudomonas aeruginosa under three representative PK/PD targets: 40% fT > MIC, 100% fT > MIC, and 100% fT > 4× MIC. The hollow fiber infection model (HFIM) was constructed, validated, and subsequently inoculated with a substantial Pseudomonas aeruginosa load (1 × 108 CFU/mL). Different meropenem regimens were administered to achieve the specified PK/PD targets. At specified intervals, samples were collected from the HFIM system and subjected to centrifugation. The resulting supernatant was utilized to determine drug concentrations, while the precipitates were used to track changes in both total and drug-resistant bacterial populations over time by the spread plate method. The HFIM accurately reproduced meropenem's pharmacokinetics in critically ill patients. All three PK/PD target groups exhibited a rapid bactericidal response within 6 h of the initial treatment. However, the 40% fT > MIC and 100% fT > MIC groups subsequently showed bacterial resurgence and resistance, whereas the 100% fT > 4× MIC group displayed sustained bactericidal activity with no evidence of drug resistance. The HFIM system revealed that maintaining 100% fT > 4× MIC offers a desirable microbiological response for critically ill patients, demonstrating strong bactericidal capacity and effective prevention of drug resistance.

Comparative pharmacodynamics and dose optimization of liposomal amphotericin B against Candida species in an in vitro pharmacokinetic/pharmacodynamic model.

As comparative pharmacokinetic/pharmacodynamic (PK/PD) studies of liposomal amphotericin B (L-AMB) against Candida spp. are lacking, we explored L-AMB pharmacodynamics against different Candida species in an in vitro PK/PD dilution model. Eight Candida glabrata, Candida parapsilosis, and Candida krusei isolates (EUCAST/CLSI AMB MIC 0.125-1 mg/L) were studied in the in vitro PK/PD model simulating L-AMB Cmax = 0.25-64 mg/L and t1/2 = 9 h. The model was validated with one susceptible and one resistant Candida albicans isolate. The Cmax/MIC-log10CFU/mL reduction from the initial inoculum was analyzed with the Emax model, and Monte Carlo analysis was performed for the standard (3 mg/kg with Cmax = 21.87 ± 12.47 mg/L) and higher (5 mg/kg with Cmax = 83 ± 35.2 mg/L) L-AMB dose. A ≥1.5 log10CFU/mL reduction was found at L-AMB Cmax = 8 mg/L against C. albicans, C. parapsilosis, and C. krusei isolates (MIC 0.25-0.5 mg/L) whereas L-AMB Cmax ≥ 32 mg/L was required for C. glabrata isolates. The in vitro PK/PD relationship followed a sigmoidal pattern (R2 ≥ 0.85) with a mean Cmax/MIC required for stasis of 2.1 for C. albicans (close to the in vivo stasis), 24/17 (EUCAST/CLSI) for C. glabrata, 8 for C. parapsilosis, and 10 for C. krusei. The probability of target attainment was ≥99% for C. albicans wild-type (WT) isolates with 3 mg/kg and for wild-type isolates of the other species with 5 mg/kg. L-AMB was four- to eightfold less active against the included non-C. albicans species than C. albicans. A standard 3-mg/kg dose is pharmacodynamically sufficient for C. albicans whereas our data suggest that 5 mg/kg may be recommendable for the included non-C. albicans species.

Clofazimine as a substitute for rifampicin improves efficacy of Mycobacterium avium pulmonary disease treatment in the hollow-fiber model.

Mycobacterium avium complex pulmonary disease is treated with an azithromycin, ethambutol, and rifampicin regimen, with limited efficacy. The role of rifampicin is controversial due to inactivity, adverse effects, and drug interactions. Here, we evaluated the efficacy of clofazimine as a substitute for rifampicin in an intracellular hollow-fiber infection model. THP-1 cells, which are monocytes isolated from peripheral blood from an acute monocytic leukemia patient, were infected with M. avium ATCC 700898 and exposed to a regimen of azithromycin and ethambutol with either rifampicin or clofazimine. Intrapulmonary pharmacokinetic profiles of azithromycin, ethambutol, and rifampicin were simulated. For clofazimine, a steady-state average concentration was targeted. Drug concentrations and bacterial densities were monitored over 21 days. Exposures to azithromycin and ethambutol were 20%-40% lower than targeted but within clinically observed ranges. Clofazimine exposures were 1.7 times higher than targeted. Until day 7, both regimens were able to maintain stasis. Thereafter, regrowth was observed for the rifampicin-containing regimen, while the clofazimine-containing regimen yielded a 2 Log10 colony forming unit (CFU) per mL decrease in bacterial load. The clofazimine regimen also successfully suppressed the emergence of macrolide tolerance. In summary, substitution of rifampicin with clofazimine in the hollow-fiber model improved the antimycobacterial activity of the regimen. Clofazimine-containing regimens merit investigation in clinical trials.

Pharmacokinetics of oral ciprofloxacin in adult patients: A scoping review.

AIMS: To map the literature on oral ciprofloxacin's pharmacokinetics and its implications for dose adjustments in specific populations. METHODS: A scoping review was performed according to the Cochrane Collaboration and JBI and reported following the PRISMA-ScR. Systematic searches on electronic databases were conducted to integrate the current evidence on ciprofloxacin's pharmacokinetics. The quality of the included studies was assessed using ClinPK's checklist. RESULTS: The search yielded 55 relevant studies. Within the traditional pharmacokinetics studies (n = 46), 86 profiles were examined (72 involving healthy patients and 14 with various clinical conditions). Oral ciprofloxacin's pharmacokinetics were influenced by covariates such as drug interactions (ferrous ions, calcium carbonate, diclofenac and itraconazole), food interactions (calcium-rich foods), elderly populations and renal impairment. Notably, variability in pharmacokinetic parameters existed among subjects, regardless of their health status, underscoring the need for comprehensive population descriptions. Population pharmacokinetic studies (n = 9) identified significant covariates for hospitalized patients, such as creatinine clearance, plasma bicarbonate, estimated glomerular filtration rate, renal replacement therapy, age, sex, total bilirubin, fat-free mass, dietary factors in renal disease, rifampicin for clearance models and body weight for volume of distribution models. Most pharmacokinetic/pharmacodynamic assessments concluded that 1200 mg/day provides a high probability of target attainment for bacteria with minimum inhibitory concentration <0.5 mg L-1 , aiming for an area under the curve for 24 h/minimum inhibitory concentration >125 h. CONCLUSIONS: This study offers a comprehensive overview regarding oral ciprofloxacin's pharmacokinetics across various health conditions. It highlights the complexities of ciprofloxacin's pharmacokinetics, emphasizing the importance of considering multiple factors in dose adjustments.

Design of a pharmacokinetic/pharmacodynamic model for administration of low dose peripheral norepinephrine during general anaesthesia.

AIMS: Intraoperative hypotension is a risk factor for kidney, heart and cognitive postoperative complications. Literature suggests that the use of low-dose peripheral norepinephrine (NOR) reduces organ dysfunction, yet its administration remains unstandardized. In this work we develop a pharmacokinetic (PK)/pharmacodynamic (PD) model of NOR and its effect on mean arterial pressure (MAP). METHODS: From June 2018 to December 2021, we included patients scheduled for elective neurosurgery and requiring vasopressors for intraoperative hypotension management at Lariboisière Hospital, Paris. Low doses of NOR were administered peripherally, and successive arterial blood samples were collected to track its plasmatic concentration. We used a compartmental modelling approach for NOR PK. We developed and compared 2 models for NOR PD on MAP. Model comparison was done using Bayes information criteria. The resulting PK/PD model parameters were fitted over the entire population and linked to age, weight, height and sex. RESULTS: We included 29 patients (age 52 [46-64] years, 69% female). NOR median time to peak effect on MAP was 74 [53-94] s. After bolus administration, MAP increased by 24% (15-31%). A 2-comparment model with depot best captured NOR PK. NOR PD effect on MAP was well represented by both Emax and Windkessel models, with better results for the former. We found that age, height and weight as well as history of smoking and hypertension were correlated with model parameters. CONCLUSION: We have developed a PK/PD model to accurately track norepinephrine plasma concentration and its effect on MAP over time, which could serve for target-controlled infusion.

Effect of incremental tazobactam concentrations on the bactericidal activity of piperacillin against ESBL-producing enterobacterales clinical isolates causing bacteraemia.

We evaluated the activity of piperacillin in relation to INCREASING TAZOBACTAM CONCENTRATION against ESBL-producing Enterobacterales collected from patients with bacteraemia. Increasing tazobactam concentration (4, 12 or 24 mg/L) exerted a reduction of piperacillin MICs under the clinical breakpoint in a concentration-dependent manner (0%, 60% and 90% of clinical isolates). Also, activity of piperacillin/tazobactam based at higher achievable serum concentrations (123/14 mg/L) is needed to reduce the bacterial growth in 92% of ESBL-producers. CHANGES IN THE PIPERACILLIN MIC IN RELATION TO INCREASING TAZOBACTAM SUGGEST THAT REALTIME TDM COULD BE USED FOR DRIVEN ANTIMICROBIAL THERAPY WITH PIPERACILLIN/TAZOBACTAM IN BSI DUE TO ESBL STRAINS.

New advances in management and treatment of cardiac implantable electronic devices infections.

Cardiac implantable electronic devices (CIED) are increasingly used worldwide, and infection of these devices remains one of the most feared complications.CIED infections (CDIs) represent a challenge for physicians and the healthcare system in general as they require prolonged hospitalization and antibiotic treatment and are burdened by high mortality and high costs, so management of CDIs must be multidisciplinary.The exact incidence of CDIs is difficult to define, considering that it is influenced by various factors mainly represented by the implanted device and the type of procedure. Risk factors for CDIs could be divided into three categories: device related, patient related, and procedural related and the etiology is mainly sustained by Gram-positive bacteria; however, other etiologies cannot be underestimated. As a matter of fact, the two cornerstones in the treatment of these infections are device removal and antimicrobial treatment. Finally, therapeutic drug monitoring and PK/PD correlations should be encouraged in all patients with CDIs receiving antibiotic therapy and may result in a better clinical outcome and a reduction in antibiotic resistance and economic costs.In this narrative review, we look at what is new in the management of these difficult-to-treat infections.

Impact of attaining aggressive vs. conservative PK/PD target on the clinical efficacy of beta-lactams for the treatment of Gram-negative infections in the critically ill patients: a systematic review and meta-analysis.

BACKGROUND: To perform a systematic review with meta-analysis with the dual intent of assessing the impact of attaining aggressive vs. conservative beta-lactams PK/PD target on the clinical efficacy for treating Gram-negative infections in critical patients, and of identifying predictive factors of failure in attaining aggressive PK/PD targets. METHODS: Two authors independently searched PubMed-MEDLINE and Scopus database from inception to 23rd December 2023, to retrieve studies comparing the impact of attaining aggressive vs. conservative PK/PD targets on clinical efficacy of beta-lactams. Independent predictive factors of failure in attaining aggressive PK/PD targets were also assessed. Aggressive PK/PD target was considered a100%fT>4xMIC, and clinical cure rate was selected as primary outcome. Meta-analysis was performed by pooling odds ratios (ORs) extrapolated from studies providing adjustment for confounders using a random-effects model with inverse variance method. RESULTS: A total of 20,364 articles were screened, and 21 observational studies were included in the meta-analysis (N = 4833; 2193 aggressive vs. 2640 conservative PK/PD target). Attaining aggressive PK/PD target was significantly associated with higher clinical cure rate (OR 1.69; 95% CI 1.15-2.49) and lower risk of beta-lactam resistance development (OR 0.06; 95% CI 0.01-0.29). Male gender, body mass index > 30 kg/m2, augmented renal clearance and MIC above the clinical breakpoint emerged as significant independent predictors of failure in attaining aggressive PK/PD targets, whereas prolonged/continuous infusion administration of beta-lactams resulted as protective factor. The risk of bias was moderate in 19 studies and severe in the other 2. CONCLUSIONS: Attaining aggressive beta-lactams PK/PD targets provided significant clinical benefits in critical patients. Our analysis could be useful to stratify patients at high-risk of failure in attaining aggressive PK/PD targets.

Pharmacokinetic/pharmacodynamic evaluation of gamithromycin against rabbit pasteurellosis.

BACKGROUND: Gamithromycin is an effective therapy for bovine and swine respiratory diseases but not utilized for rabbits. Given its potent activity against respiratory pathogens, we sought to determine the pharmacokinetic profiles, antimicrobial activity and target pharmacokinetic/pharmacodynamic (PK/PD) exposures associated with therapeutic effect of gamithromycin against Pasteurella multocida in rabbits. RESULTS: Gamithromycin showed favorable PK properties in rabbits, including high subcutaneous bioavailability (86.7 ± 10.7%) and low plasma protein binding (18.5-31.9%). PK analysis identified a mean plasma peak concentration (Cmax) of 1.64 ± 0.86 mg/L and terminal half-life (T1/2) of 31.5 ± 5.74 h after subcutaneous injection. For P. multocida, short post-antibiotic effects (PAE) (1.1-5.3 h) and post-antibiotic sub-inhibitory concentration effects (PA-SME) (6.6-9.1 h) were observed after exposure to gamithromycin at 1 to 4× minimal inhibitory concentration (MIC). Gamithromycin demonstrated concentration-dependent bactericidal activity and the PK/PD index area under the concentration-time curve over 24 h (AUC24h)/MIC correlated well with efficacy (R2 > 0.99). The plasma AUC24h/MIC ratios of gamithromycin associated with the bacteriostatic, bactericidal and bacterial eradication against P. multocida were 15.4, 24.9 and 27.8 h in rabbits, respectively. CONCLUSIONS: Subcutaneous administration of 6 mg/kg gamithromycin reached therapeutic concentrations in rabbit plasma against P. multocida. The PK/PD ratios determined herein in combination with ex vivo activity and favorable rabbit PK indicate that gamithromycin may be used for the treatment of rabbit pasteurellosis.

Evaluation the kill rate and mutant selection window of danofloxacin against Actinobacillus pleuropneumoniae in a peristaltic pump model.

BACKGROUND: Actinobacillus pleuropneumoniae is a serious pathogen in pigs. The abundant application of antibiotics has resulted in the gradual emergence of drugresistant bacteria, which has seriously affected treatment of disease. To aid measures to prevent the emergence and spread of drug-resistant bacteria, herein, the kill rate and mutant selection window (MSW) of danofloxacin (DAN) against A. pleuropneumoniae were evaluated. METHODS: For the kill rate study, the minimum inhibitory concentration (MIC) was tested using the micro dilution broth method and time-killing curves of DAN against A. pleuropneumoniae grown in tryptic soy broth (TSB) at a series drug concentrations (from 0 to 64 MIC) were constructed. The relationships between the kill rate and drug concentrations were analyzed using a Sigmoid Emax model during different time periods. For the MSW study, the MIC99 (the lowest concentration that inhibited the growth of the bacteria by ≥ 99%) and mutant prevention concentration (MPC) of DAN against A. pleuropneumoniae were measured using the agar plate method. Then, a peristaltic pump infection model was established to simulate the dynamic changes of DAN concentrations in pig lungs. The changes in number and sensitivity of A. pleuropneumoniae were measured. The relationships between pharmacokinetic/pharmacodynamic parameters and the antibacterial effect were analyzed using the Sigmoid Emax model. RESULTS: In kill rate study, the MIC of DAN against A. pleuropneumoniae was 0.016 µg/mL. According to the kill rate, DAN exhibited concentration-dependent antibacterial activity against A. pleuropneumoniae. A bactericidal effect was observed when the DAN concentration reached 4-8 MIC. The kill rate increased constantly with the increase in DAN concentration, with a maximum value of 3.23 Log10 colony forming units (CFU)/mL/h during the 0-1 h period. When the drug concentration was in the middle part of the MSW, drugresistant bacteria might be induced. Therefore, the dosage should be avoided to produce a mean value of AUC24h/MIC99 (between 31.29 and 62.59 h. The values of AUC24h/MIC99 to achieve bacteriostatic, bactericidal, and eradication effects were 9.46, 25.14, and > 62.59 h, respectively. CONCLUSION: These kill rate and MSW results will provide valuable guidance for the use of DAN to treat A. pleuropneumoniae infections.

Preclinical characterization of the absorption and disposition of the brain penetrant PI3K/mTOR inhibitor paxalisib and prediction of its pharmacokinetics and efficacy in human.

Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults. Available treatments have not markedly improved patient survival in the last twenty years. However, genomic investigations have showed that the PI3K pathway is frequently altered in this glioma, making it a potential therapeutic target.Paxalisib is a brain penetrant PI3K/mTOR inhibitor (mouse Kp,uu 0.31) specifically developed for the treatment of GBM. We characterised the preclinical pharmacokinetics and efficacy of paxalisib and predicted its pharmacokinetics and efficacious dose in humans.Plasma protein binding of paxalisib was low, with the fraction unbound ranging from 0.25 to 0.43 across species. The hepatic clearance of paxalisib was predicted to be low in mice, rats, dogs and humans, and high in monkeys, from hepatocytes incubations. The plasma clearance was low in mice, moderate in rats and high in dogs and monkeys. Oral bioavailability ranged from 6% in monkeys to 76% in rats.The parameters estimated from the pharmacokinetic/pharmacodynamic modelling of the efficacy in the subcutaneous U87 xenograft model combined with the human pharmacokinetics profile predicted by PBPK modelling suggested that a dose of 56 mg may be efficacious in humans. Paxalisib is currently tested in Phase III clinical trials.

Strategies for successful dose optimization in oncology drug development: a practical guide.

Dose optimization is a critical challenge in drug development. Historically, dose determination in oncology has followed a divergent path from other non-oncology therapeutic areas due to the unique characteristics and requirements in Oncology. However, with the emergence of new drug modalities and mechanisms of drugs in oncology, such as immune therapies, radiopharmaceuticals, targeted therapies, cytostatic agents, and others, the dose-response relationship for efficacy and toxicity could be vastly varied compared to the cytotoxic chemotherapies. The doses below the MTD may demonstrate similar efficacy to the MTD with an improved tolerability profile, resembling what is commonly observed in non-oncology treatments. Hence, alternate strategies for dose optimization are required for new modalities in oncology drug development. This paper delves into the historical evolution of dose finding methods from non-oncology to oncology, highlighting examples and summarizing the underlying drivers of change. Subsequently, a practical framework and guidance are provided to illustrate how dose optimization can be incorporated into various stages of the development program. We provide the following general recommendations: 1) The objective for phase I is to identify a dose range rather than a single MTD dose for subsequent development to better characterize the safety and tolerability profile within the dose range. 2) At least two doses separable by PK are recommended for dose optimization in phase II. 3) Ideally, dose optimization should be performed before launching the confirmatory study. Nevertheless, innovative designs such as seamless II/III design can be implemented for dose selection and may accelerate the drug development program.

Evaluation of prompt engineering strategies for pharmacokinetic data analysis with the ChatGPT large language model.

To systematically assess the ChatGPT large language model on diverse tasks relevant to pharmacokinetic data analysis. ChatGPT was evaluated with prototypical tasks related to report writing, code generation, non-compartmental analysis, and pharmacokinetic word problems. The writing task consisted of writing an introduction for this paper from a draft title. The coding tasks consisted of generating R code for semi-logarithmic graphing of concentration-time profiles and calculating area under the curve and area under the moment curve from time zero to infinity. Pharmacokinetics word problems on single intravenous, extravascular bolus, and multiple dosing were taken from a pharmacokinetics textbook. Chain-of-thought and problem separation were assessed as prompt engineering strategies when errors occurred. ChatGPT showed satisfactory performance on the report writing, code generation tasks and provided accurate information on the principles and methods underlying pharmacokinetic data analysis. However, ChatGPT had high error rates in numerical calculations involving exponential functions. The outputs generated by ChatGPT were not reproducible: the precise content of the output was variable albeit not necessarily erroneous for different instances of the same prompt. Incorporation of prompt engineering strategies reduced but did not eliminate errors in numerical calculations. ChatGPT has the potential to become a powerful productivity tool for writing, knowledge encapsulation, and coding tasks in pharmacokinetic data analysis. The poor accuracy of ChatGPT in numerical calculations require resolution before it can be reliably used for PK and pharmacometrics data analysis.

Go beyond the limits of genetic algorithm in daily covariate selection practice.

Covariate identification is an important step in the development of a population pharmacokinetic/pharmacodynamic model. Among the different available approaches, the stepwise covariate model (SCM) is the most used. However, SCM is based on a local search strategy, in which the model-building process iteratively tests the addition or elimination of a single covariate at a time given all the others. This introduces a heuristic to limit the searching space and then the computational complexity, but, at the same time, can lead to a suboptimal solution. The application of genetic algorithms (GAs) for covariate selection has been proposed as a possible solution to overcome these limitations. However, their actual use during model building is limited by the extremely high computational costs and convergence issues, both related to the number of models being tested. In this paper, we proposed a new GA for covariate selection to address these challenges. The GA was first developed on a simulated case study where the heuristics introduced to overcome the limitations affecting currently available GA approaches resulted able to limit the selection of redundant covariates, increase replicability of results and reduce convergence times. Then, we tested the proposed GA on a real-world problem related to remifentanil. It obtained good results both in terms of selected covariates and fitness optimization, outperforming the SCM.

Using Pharmacokinetic-Pharmacodynamic Modeling to Study the Main Active Substances of the Anticancer Effect in Mice from Panax ginseng-Ophiopogon japonicus.

Ginseng Radix et Rhizoma Rubra (Panax ginseng C.A. Mey, Hongshen, in Chinese) and Ophiopogonis Radix (Ophiopogon japonicus (L.f) Ker-Gawl., Maidong, in Chinese) are traditional Chinese herbal pairs, which were clinically employed to enhance the immune system of cancer patients. This study employed the pharmacokinetic and pharmacodynamic (PK-PD) spectrum-effect association model to investigate the antitumor active substances of P. ginseng and O. japonicus (PG-OJ). The metabolic processes of 20 major bioactive components were analyzed using Ultra-Performance Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (UPLC-MS/MS) in the lung tissue of tumor-bearing mice treated with PG-OJ. The ELISA method was employed to detect the levels of TGF-ß1, TNF-α, and IFN-γ in the lung tissue of mice at various time points, and to analyze their changes after drug administration. The results showed that all components presented a multiple peaks absorption pattern within 0.083 to 24 h post-drug administration. The tumor inhibition rate of tumor and repair rate of IFN-γ, TNF-α, and TGF-ß1 all increased, indicating a positive therapeutic effect of PG-OJ on A549 tumor-bearing mice. Finally, a PK-PD model based on the GBDT algorithm was developed for the first time to speculate that Methylophiopogonanone A, Methylophiopogonanone B, Ginsenoside Rb1, and Notoginsenoside R1 are the main active components in PG-OJ for lung cancer treatment.

Pharmacodynamics of Temocillin in Neutropenic Murine Infection Models.

Temocillin is used for the treatment of various infections caused by Enterobacterales. The pharmacokinetic (PK)/pharmacodynamic (PD) index that is best correlated with the activity of beta-lactams is the percentage of time that the unbound concentration exceeds the MIC (%fT>MIC). However, the %fT>MIC needed for a bacteriostatic or killing effect of temocillin is unknown in thigh and lung infection models. In the present study, we studied the temocillin PK in plasma and epithelial lining fluid (ELF) of infected neutropenic mice and determined the plasma exposure-response relationships for Escherichia coli and Klebsiella pneumoniae. Neutropenic murine thigh and lung infection models were used. The bacterial loads in the thighs or lungs were determined. A sigmoid maximum-effect model was used to fit the plasma exposure-response relationship. A one-compartment model with first-order absorption best described temocillin PK (clearance [CL], 1.03 L/h/kg; volume of distribution [V], 0.457 L/kg). Protein binding was 78.2% ± 1.3% across different plasma concentrations. A static effect was achieved for all strains in both the thigh and lung infection models. However, the median %fT>MIC needed for a static effect was much lower in the lung infection model (27.8% for E. coli and 38.2% for K. pneumoniae) than in the thigh infection model (65.2% for E. coli and 64.9% for K. pneumoniae). A 1-log kill was reached for all strains in the lung infection model (median %fT>MIC values of 42.1% for E. coli and 44.1% for K. pneumoniae) and 7 out of 8 strains in the thigh infection model (median %fT>MIC values of 85.4% for E. coli and 74.5% for K. pneumoniae). These data support the use of temocillin in patients with pneumonia.

Population Pharmacokinetic and Pharmacodynamic Analysis of Valganciclovir for Optimizing Preemptive Therapy of Cytomegalovirus Infections in Kidney Transplant Recipients.

This study aimed to develop a population pharmacokinetic/pharmacodynamic (PK/PD) model of valganciclovir for preemptive therapy of cytomegalovirus (CMV) infection in kidney transplant patients. A population PK/PD model was developed with Monolix. Ganciclovir concentrations and CMV viral loads were obtained retrospectively from kidney transplant patients receiving routine clinical care. Ten thousand Monte Carlo simulations were performed with the licensed dosages adjusted for renal function to assess the probability of attaining a viral load target of ≤290 and ≤137 IU/mL. Fifty-seven patients provided 343 ganciclovir concentrations and 328 CMV viral loads for PK/PD modeling. A one-compartment pharmacokinetic model coupled with an indirect viral turnover growth model with stimulation of viral degradation pharmacodynamic model was devised. Simulations showed that 1- and 2-log10 reduction of CMV viral load mostly occurred between a median of 5 to 6 and 12 to 16 days, respectively. The licensed dosages achieved a probability of reaching the viral load target ≥90% at days 35 to 49 and 42 to 56 for the thresholds of ≤290 and ≤137 IU/mL, respectively. Simulations indicate that in patients with an estimated glomerular filtration rate of 10 to 24 mL/min/1.73m2, a dose increase to 450 mg every 36 h may reduce time to optimal viral load target to days 42 and 49 from a previous time of 49 and 56 days for the thresholds of ≤290 and ≤137 IU/mL, respectively. Currently licensed dosages of valganciclovir for preemptive therapy of CMV infection may achieve a viral load reduction within the first 2 weeks, but treatment should continue for ≥35 days to ensure viral load suppression.

Pharmacokinetic/Pharmacodynamic Index Linked to In Vivo Efficacy of the Ampicillin-Ceftriaxone Combination against Enterococcus faecalis.

Combination therapy with ampicillin plus ceftriaxone (AMP+CRO) is the first-line therapy for treating severe infections due to Enterococcus faecalis. However, the pharmacokinetic/pharmacodynamic (PK/PD) index linked to the in vivo efficacy of the combination is not yet defined, hindering dose optimization in the clinic. Because classical PK/PD indices are not directly applicable to antimicrobial combinations, two novel indices were tested in the optimized murine model of infection by E. faecalis to delineate the potentiation of AMP by CRO: the time above the CRO threshold (T>threshold) and the time above the AMP instantaneous MIC (T>MICi). The potential clinical relevance was evaluated by simulating human doses of AMP and CRO. Hill's equation fitted well the exposure-response data in terms of T>threshold, with a CRO threshold of 1 mg/L. The required exposures were 46%, 49%, and 52% for stasis and 1- and 2-log10 killing, respectively. Human ceftriaxone doses of 2 g every 12 h (q12h) would reach the target in >90% of strains with thresholds ≤64 mg/L. The AMP T>MICi index also fitted well, and the required exposures were 37%, 41%, and 46% for stasis and 1- and 2-log10 killing, respectively. In humans, the addition of CRO would allow use of lower AMP doses to reach the same T>MICi and to treat strains with higher MICs. This is the first report of the PK/PD indices and required magnitudes linked to AMP+CRO against E. faecalis; these results can be used as the basis to guide the design of clinical trials to improve combined therapy against enterococci.