Pharmacokinetics Of Meropenem Research Articles

Dosage Optimization Using Physiologically Based Pharmacokinetic Modeling for Pediatric Patients with Renal Impairment: A Case Study of Meropenem.

The pharmacokinetics of renally eliminated antibiotics can be influenced by changes associated with renal function and development in a growing subject. Little is known about the effects of renal insufficiency on the pharmacokinetics of meropenem in pediatric subjects. The aim of this study was to develop a physiologically based pharmacokinetic (PBPK) model of meropenem for pediatric patients that can be used to optimize meropenem dosing in pediatric patients with renal impairment (RI). The PBPK model was developed using GastroPlus™ 9.9 based on clinical data obtained from the literature and then scaled to pediatric patients with RI for dose optimization of meropenem. The goodness of fit of the model was assessed by comparing the predicted values of AUC0-t, AUC0-α, and Cmax with the observed data and the average fold errors (AFE). The AFE values for AUC0-t, AUC0-α, and Cmax in the pediatric population were measured to be 1.60, 1.08, and 1.48, respectively. In addition, dose optimization was performed in virtual pediatric populations with varying degrees of RI and a dose reduction to 10mg/kg and 7.5mg/kg was recommended for moderate and severe RI, respectively. In all virtual pediatric populations with RI, the plasma concentration reached the recommended time above the minimum inhibitory concentration (MIC) at all optimized doses. The developed PBPK model for meropenem provides a quantitative tool to assess the impact of RI on the pharmacokinetics of meropenem in pediatric patients, which may be useful for optimizing the dosing regimen.

Impact of pediatric continuous renal replacement therapy parameters on Meropenem, Piperacillin and tazobactam pharmacokinetics: an in vitro Model

ABSTRACT Background Limited data exist on how continuous renal replacement therapy (CRRT) affects antimicrobial dosing in pediatric patients. This study examined the impact of pediatric CRRT parameters on the pharmacokinetics (PK) of meropenem, piperacillin, and tazobactam using an in vitro CRRT model. Research design and methods An in vitro CRRT model with a pediatric ST60 circuit was used to assess antimicrobial clearance during continuous veno-venous hemodialysis (CVVHD) or hemofiltration (CVVH). Antimicrobials were administered intermittently or continuously, with samples taken pre- and post-filter, and from the effluent. The model tested two conditions: 1) off treatment (0 mL/kg/h), and 2) an elimination phase with CRRT flow rates ranging from 40 to 400 mL/kg/h. Results Clearance of meropenem, piperacillin, and tazobactam increased significantly with higher dialyzate/ultrafiltration flow rates (p < 0.001). Median clearance rates differed significantly by CRRT flow rates and modality (p < 0.001). Under CVVHD, the saturation coefficient (Sa) decreased with increasing dialyzate flow rates, while under CVVH, the sieving coefficient (Sc) remained stable regardless of ultrafiltration rates. Conclusions The clearance of low protein-binding, low molecular weight antimicrobials increases with higher CRRT effluent flow rates, with modality-specific differences in clearance dynamics.

Population Pharmacokinetics of Meropenem Across the Adult Lifespan.

We conducted an opportunistic pharmacokinetic study to evaluate the population pharmacokinetics of meropenem, an antimicrobial commonly used to treat Gram-negative infections in adults of different ages, including older adults, and determined optimal dosing regimens. A total of 99 patients were included. The population pharmacokinetic models used had two compartments: zero-order input and linear elimination. Covariates evaluated included renal function, body size, age, sex, vasopressor use, and frailty, using the Canadian Study of Health and Aging Clinical Frailty score (in patients aged ≥ 65 years). We simulated optimal dosing regimens by renal function and by age group to achieve therapeutic target attainment. Participants' ages ranged from 20 to 95 years, with an average age of 57.4 years, and 22% (23/103) were aged ≥ 75 years. Creatinine clearance had the greatest impact on the clearance of meropenem. After accounting for renal function and body size, no other covariates resulted in a significant impact on the pharmacokinetics of meropenem. Simulations indicated that patients with normal renal function achieved ≥ 90% target attainment only for organisms with minimum inhibitory concentrations (MICs) ≤ 4 mg/L using the least strict surrogate target of unbound concentration > MIC (fT>MIC) for 40% of the dosing interval. For the conservative target fT>4xMIC for 100% of the dosing interval, extended infusion may be required even for organisms with MICs up to 0.25 mg/L. Patients with renal impairment could achieve ≥ 90% target attainment for more resistant organisms, but extended infusion did not increase the MICs up to which target attainment could be achieved. Meropenem dosing should be based on renal function rather than age. For patients without renal impairment, extended infusion may increase the probability of target attainment.

Physiologically-based pharmacokinetic modelling in sepsis; a tool to elucidate how pathophysiology affects meropenem pharmacokinetics: A PBPK model of meropenem in sepsis

Applying physiologically-based pharmacokinetic (PBPK) modelling in sepsis could help to better understand how PK changes are influenced by drug- and patient-related factors. We aimed to elucidate the influence of sepsis pathophysiology on the PK of meropenem by applying PBPK modelling. A whole-body meropenem PBPK model was developed and evaluated in healthy individuals, and renally impaired non-septic patients. Sepsis-induced physiological changes in body composition, organ blood flow, kidney function, albumin, and haematocrit were implemented according to a previously proposed PBPK sepsis model. Model performance was evaluated, and a local sensitivity analysis was conducted. The model-predicted PK metrics (AUC, Cmax, CL, Vss) were within 1.33-fold-error margin of published data for 87.5% of the simulated profiles in healthy individuals. In sepsis, the model provided good predictions for literature-digitised average plasma and tissue exposure data, where the model-predicted AUC was within 1.33-fold-error margin for 9 out 11 simulated study profiles. Furthermore, the model was applied to individual plasma concentration data from 52 septic patients, where the model-predicted AUC, Cmax, and CL had a fold-error ratio range of 0.98-1.12, with alignment of the predicted and observed variability. For Vss, the fold-error ratio was 0.81, and the model underpredicted the population variability. CL was sensitive to renal plasma clearance, and kidney volume, whereas Vss was sensitive to the unbound fraction, organ volume fraction of the interstitial compartment, and the organ volume. These findings may be extended to more diverse drug types and support a more mechanistic understanding of the effect of sepsis on drug exposure.

Safety, tolerability and pharmacokinetics of subcutaneous meropenem as an alternative to intravenous administration.

Subcutaneous delivery of antibiotics is a practical alternative to IV administration. Meropenem is commonly used to treat infections caused by resistant Gram-negative organisms. This was a prospective, crossover self-controlled study in 11 stable inpatients established on meropenem. Participants received a single dose of subcutaneous meropenem, in 50 mL normal saline via gravity feed. Venous blood sampling was performed at baseline, 0.5, 1, 2, 4 and 8 h following the subcutaneous and IV doses. Antibiotic concentrations were measured using UPLC-MS/MS. Pharmacokinetic data were analysed using a non-linear mixed-effects modelling approach. Pain scores and infusion site reactions (oedema/erythema) were assessed. Subcutaneous meropenem was well tolerated. The bioavailability of subcutaneous administration was 81.5% (95% CI 71.6%-93.2%). Increasing BMI was associated with slower absorption from subcutaneous tissue. Compared with IV, subcutaneous administration resulted in lower peak and higher trough concentrations. Despite the lower bioavailability observed, the PTA for free drug concentrations greater than the MIC for more than 40% of the time between doses was higher for subcutaneous than IV administration at MIC values between 0.03 and 8 mg/L. Simulated subcutaneous doses of 1.5 g twice daily, or 3 g continuous 24 h infusion had improved PTA relative to standard IV dosing of 1 g three times daily. Subcutaneous meropenem appears to be well tolerated and has a favourable pharmacokinetic profile. Either 1.5 g twice daily or 3 g as a 24 h subcutaneous infusion could be considered for future evaluation.

Population Pharmacokinetic Modeling of Cefepime, Meropenem, and Piperacillin-Tazobactam in Patients with Cystic Fibrosis.

Patients with cystic fibrosis (CF) experience recurrent bacterial pulmonary exacerbations. Management of these infections is increasingly challenging due to decreased antimicrobial susceptibility to beta-lactam antibiotics. The pharmacokinetics of these agents are inadequately characterized in patients with CF. One hundred fifty-five pediatric and adult participants with CF receiving cefepime (n=82), meropenem (n=42), or piperacillin-tazobactam (n=31) were enrolled. Opportunistic blood samples were obtained during hospitalization. Population PK analysis was conducted using nonlinear mixed-effects modeling. Clinical and demographic characteristics were evaluated as potential covariates. Monte Carlo simulations were performed to evaluate probability of target attainment (PTA) for different dosing regimens. Estimated creatinine clearance, and total or lean body weight, affected the pharmacokinetics of cefepime and meropenem. No covariates were identified for piperacillin and tazobactam. In the cefepime group, a 3-h infusion achieved higher PTA than a 0.5-h infusion for all participants. Estimated breakpoints (the respective minimum inhibitory concentration (MIC) up to which ≥90% of patients are predicted to reach a PK/PD target) were two- to four-fold higher in pediatric participants receiving a 3-h vs. 0.5-h infusion. In the meropenem group, increased creatinine clearance led to reduced PTA. In the piperacillin-tazobactam group, total daily dose and mode of administration were principal drivers of PTA. Standard dosing regimens fail to achieve specific MIC targets in patients with CF. Therefore, clinicians should incorporate local antibiograms and PK models to determine optimal dosing. Further PK optimization to account for interindividual differences could be achieved by real-time beta-lactam therapeutic drug monitoring.

Physiologically-based pharmacokinetic/pharmacodynamic modeling of meropenem in critically ill patients

This study aimed to develop a physiologically based pharmacokinetic/pharmacodynamic model (PBPK/PD) of meropenem for critically ill patients. A PBPK model of meropenem in healthy adults was established using PK-Sim software and subsequently extrapolated to critically ill patients based on anatomic and physiological parameters. The mean fold error (MFE) and geometric mean fold error (GMFE) methods were used to compare the differences between predicted and observed values of pharmacokinetic parameters Cmax, AUC0-∞, and CL to evaluate the accuracy of the PBPK model. The model was verified using meropenem plasma samples obtained from Intensive Care Unit (ICU) patients, which were determined by HPLC-MS/MS. After that, the PBPK model was combined with a PKPD model, which was developed based on f%T > MIC. Monte Carlo simulation was utilized to calculate the probability of target attainment (PTA) in patients. The developed PBPK model successfully predicted the meropenem disposition in critically ill patients, wherein the MFE average and GMFE of all predicted PK parameters were within the 1.25-fold error range. The therapeutic drug monitoring (TDM) of meropenem was conducted with 92 blood samples from 31 ICU patients, of which 71 (77.17%) blood samples were consistent with the simulated value. The TDM results showed that meropenem PBPK modeling is well simulated in critically ill patients. Monte Carlo simulations showed that extended infusion and frequent administration were necessary to achieve curative effect for critically ill patients, whereas excessive infusion time (> 4 h) was unnecessary. The PBPK/PD modeling incorporating literature and prospective study data can predict meropenem pharmacokinetics in critically ill patients correctly. Our study provides a reference for dose adjustment in critically ill patients.

Meropenem pharmacokinetics in cerebrospinal fluid: comparing intermittent and continuous infusion strategies in critically ill patients-a prospective cohort study.

This study is registered with ClinicalTrials.gov as NCT04426383.

Population pharmacokinetics of meropenem in critically ill patients.

The pharmacokinetics of meropenem are significantly altered in critically ill patients. A population pharmacokinetic study was designed to estimate typical values of meropenem clearance in critically ill patients and evaluate potential factors of influence. After meropenem reached a steady state in each patient, two blood samples were taken within the dose interval. The one-compartment pharmacokinetic model based on the data from 101 intensive care unit patients was built using NONMEM software. Typical values of meropenem clearance and volume of distribution were 3.80 L/h and 3.52 L, respectively. In the final model, meropenem clearance was influenced by serum concentrations of creatinine (CRE), leukocyte count (WBC), hypertension (HTA), and concomitant use of vancomycin (VAN) or colistimethate (COL): CL (L/h) = 5.29 × CRE ^ 0.000001 × WBCs ^ (-0.165) + 0.000001 × HTA + 0.825 × VAN + 1.28 × COL. In order to achieve effective plasma concentrations of meropenem in critically ill patients, the meropenem dosing regimen should be adjusted according to individual values of drug clearance.

Population Pharmacokinetic Modeling of Unbound Meropenem in Patients Undergoing Continuous Renal Replacement Therapy: An Observational Cohort Study.

The most effective dosing strategy of meropenem for patients undergoing continuous renal replacement therapy (CRRT) remains uncertain. This study aimed to analyze the population pharmacokinetics (popPKs) of unbound meropenem and establish an appropriate dosing approach. This prospective study involved 19 patients for the development of a popPK model and an additional 10 for its validation. Ethical approval was obtained. The clearance of unbound meropenem was influenced by the sequential organ failure assessment (SOFA) score [=2.22 × (SOFA score/12)^1.88] and the effluent flow rate from the CRRT device, with an interindividual variability of 44.5%. The volume of distribution was affected by the simplified acute physiology score II [=23.1 × (simplified acute physiology score II/52)^1.54]. Monte Carlo simulations suggested meropenem doses ranging from 1.0 to 3.0 g/d using continuous infusion to achieve a target time above the 4 times of minimum inhibitory concentration of the unbound form (% f T >4×MIC ) of 100% for definitive therapy. For empirical therapy, a dose of 1.0 g/d using continuous infusion was recommended to target % f T >MIC of 100%. This study developed a popPK model for unbound meropenem in patients undergoing CRRT and formulated dosing guidelines. UMIN000024321.

Meropenem Disposition in Neonatal and Pediatric Extracorporeal Membrane Oxygenation and Continuous Renal Replacement Therapy.

This study aimed to characterize the impact of extracorporeal membrane oxygenation (ECMO) on the pharmacokinetics (PK) of meropenem in neonates and children and to provide recommendations for meropenem dosing in this specific population of patients. Therapeutic drug monitoring (152 meropenem plasma concentrations) data from 45 patients (38 received ECMO) with a body weight (BW) of 7.88 (3.62-11.97) kg (median (interquartile range)) and postnatal age of 3 (0-465) days were collected. The population PK analysis was performed using NONMEM V7.3.0. Monte Carlo simulations were performed to assess the probability of target achievement (PTA) for 40% of time the free drug remained above the minimum inhibitory concentration (fT > MIC) and 100% fT > MIC. BW was found to be a significant covariate for the volume of distribution (Vd) and clearance (CL). Additionally, continuous renal replacement therapy (CRRT) was associated with a two-fold increase in Vd. In the final model, the CL and Vd for a typical patient with a median BW of 7.88 kg that was off CRRT were 1.09 L/h (RSE = 8%) and 3.98 L (14%), respectively. ECMO did not affect meropenem PK, while superimposed CRRT significantly increased Vd. We concluded that current dosing regimens provide acceptably high PTA for MIC ≤ 4 mg/L for 40% fT > MIC, but individual dose adjustments are needed for 100% fT > MIC.

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.

Impact of Various Estimated Glomerular Filtration Rate Equations on the Pharmacokinetics of Meropenem in Critically Ill Adults.

Meropenem dosing is typically guided by creatinine-based estimated glomerular filtration rate (eGFR), but creatinine is a suboptimal GFR marker in the critically ill. This study aimed to develop and qualify a population pharmacokinetic model for meropenem in critically ill adults and to determine which eGFR equation based on creatinine, cystatin C, or both biomarkers best improves model performance. This single-center study evaluated adults hospitalized in an ICU who received IV meropenem from 2018 to 2022. Patients were excluded if they had acute kidney injury, were on kidney replacement therapy, or were treated with extracorporeal membrane oxygenation. Two cohorts were used for population pharmacokinetic modeling: a richly sampled development cohort (n = 19) and an opportunistically sampled qualification cohort (n = 32). A nonlinear mixed-effects model was developed using parametric methods to estimate meropenem serum concentrations. The best-fit structural model in the richly sampled development cohort was a two-compartment model with first-order elimination. The final model included time-dependent weight normalized to a 70-kg adult as a covariate for volume of distribution (Vd) and time-dependent eGFR for clearance. Among the eGFR equations evaluated, eGFR based on creatinine and cystatin C expressed in mL/min best-predicted meropenem clearance. The mean (se) Vd in the final model was 18.2 (3.5) liters and clearance was 11.5 (1.3) L/hr. Using the development cohort as the Bayesian prior, the opportunistically sampled cohort demonstrated good accuracy and low bias. Contemporary eGFR equations that use both creatinine and cystatin C improved meropenem population pharmacokinetic model performance compared with creatinine-only or cystatin C-only eGFR equations in adult critically ill patients.

Meropenem extraction by ex vivo extracorporeal life support circuits.

Meropenem is a broad-spectrum carbapenem-type antibiotic commonly used to treat critically ill patients infected with extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. As many of these patients require extracorporeal membrane oxygenation (ECMO) and/or continuous renal replacement therapy (CRRT), it is important to understand how these extracorporeal life support circuits impact meropenem pharmacokinetics. Based on the physicochemical properties of meropenem, it is expected that ECMO circuits will minimally extract meropenem, while CRRT circuits will rapidly clear meropenem. The present study seeks to determine the extraction of meropenem from ex vivo ECMO and CRRT circuits and elucidate the contribution of different ECMO circuit components to extraction. Standard doses of meropenem were administered to three different configurations (n=3 per configuration) of blood-primed ex vivo ECMO circuits and serial sampling was conducted over 24h. Similarly, standard doses of meropenem were administered to CRRT circuits (n=4) and serial sampling was conducted over 4h. Meropenem was administered to separate tubes primed with circuit blood to serve as controls to account for drug degradation. Meropenem concentrations were quantified, and percent recovery was calculated for each sample. Meropenem was cleared at a similar rate in ECMO circuits of different configurations (n=3) and controls (n=6), with mean (standard deviation) recovery at 24h of 15.6% (12.9) in Complete circuits, 37.9% (8.3) in Oxygenator circuits, 47.1% (8.2) in Pump circuits, and 20.6% (20.6) in controls. In CRRT circuits (n=4) meropenem was cleared rapidly compared with controls (n=6) with a mean recovery at 2h of 2.36% (1.44) in circuits and 93.0% (7.1) in controls. Meropenem is rapidly cleared by hemodiafiltration during CRRT. There is minimal adsorption of meropenem to ECMO circuit components; however, meropenem undergoes significant degradation and/or plasma metabolism at physiological conditions. These ex vivo findings will advise pharmacists and physicians on the appropriate dosing of meropenem.

2551. Assessing Meropenem Concentrations in Children with Septic Shock: Population-Based Pharmacokinetic (PK) Modeling of Meropenem Demonstrates Variability from Acute Kidney (AKI) to Augmented Renal Clearance (ARC)

Abstract Background The primary objective of this study was to characterize meropenem (MERO) pharmacokinetics (PK) in critically ill infants and children with septic shock to develop dosing recommendations to achieve therapeutic drug exposure in this complex population with a spectrum of renal function from augmented renal clearance (ARC) to acute kidney injury (AKI). Methods Children ≥4 weeks old hospitalized with septic shock requiring fluid resuscitation and pressors, receiving MERO 20 mg/kg IV every 8 hr as standard-of-care, were enrolled and studied prospectively from 2019 to 2023. Population PK modeling was used to derive Bayesian post-hoc PK parameters (NONMEM 7.3). Renal biomarkers (serum creatinine [SCr], cystatin C [CYS], serum neutrophil gelatinase-associated lipocalin [NGAL]) were evaluated as covariates. Estimated glomerular filtration rate (e-GFR) was calculated by the modified Schwartz equation. Results A total of 304 MERO serum concentrations were included from 26 participants. Median age was 12.6 yr (range 1.2-19.6); weight 38.4 kg (10-98); SCr 0.36 mg/dL (0.09-2.57); CYS 448.9 mg/d (178.3-1824.1), and NGAL 176.05 ng/mL (29.3-1000). Median MERO serum concentration was 11 mcg/mL (range 0.033-217, interquartile range [IQR] 1.873-37.85). A two-compartment model with allometrically scaled weight on clearance (0.75) best described the data. Significant covariates (final model) were e-GFR, CYS, NGAL, age, diagnosis of appendicitis and albumin. Using the final model, the median CL was 0.15 (range 0.05-0.51, interquartile range [IQR] 0.06-0.25) L/hr/kg and V1 0.20 (0.07-0.57, IQR 0.12-0.31) L/kg, with GFR 139 (23-364, IQR 93-204) mL/min/1.73 m2 (Figure). The distribution of MERO concentrations, CL and GFR across quartiles documents wide variations in renal function observed in septic shock, from AKI to ARC (Figure). Meropenem Serum Concentration, Meropenem Renal Clearance, and Glomerular Filtration Rate, by Quartiles Conclusion Wide variation in MERO plasma exposure was documented in children with septic shock across the spectrum of renal function. GFR-based dosing recommendations may optimize MERO dosing and improve outcomes in this population. This work was supported by NICHD grant 1 R01 HD095547-01 Disclosures Edmund Capparelli, PharmD, Melinta: Advisor/Consultant

Testing the mutant selection window hypothesis with meropenem: In vitro model study with OXA-48-producing Klebsiella pneumoniae.

OXA-48 carbapenemases are frequently expressed by Klebsiella pneumoniae clinical isolates; they decrease the effectiveness of carbapenem therapy, particularly with meropenem. Among these isolates, meropenem-susceptible carbapenemase-producers may show decreased meropenem effectiveness. However, the probability of the emergence of resistance in susceptible carbapenemase-producing isolates and its dependence on specific K. pneumoniae meropenem MICs is not completely known. It is also not completely clear what resistance patterns will be exhibited by these bacteria exposed to meropenem, if they would follow the patterns of non-beta-lactamase-producing bacteria and other than beta-lactams antibiotics. These issues might be clarified if patterns of meropenem resistance related to the mutant selection window (MSW) hypothesis. To test the applicability of the MSW hypothesis to meropenem, OXA-48-carbapenemase-producing K. pneumoniae clinical isolates with MICs in a 64-fold range (from susceptible to resistant) were exposed to meropenem in a hollow-fiber infection model; epithelial lining fluid meropenem pharmacokinetics were simulated following administration of 2 grams every 8 hours in a 3-hour infusion. Strong bell-shaped relationships between the meropenem daily dose infused to the model as related to the specific isolate MIC and both the antimicrobial effect and the emergence of resistance were observed. The applicability of the MSW hypothesis to meropenem and carbapenemase producing K. pneumoniae was confirmed. Low meropenem efficacy indicates very careful prescribing of meropenem to treat K. pneumoniae infections when the causative isolate is confirmed as an OXA-48-carbapenemase producer.

Meropenem Pharmacokinetics and Target Attainment in Critically Ill Patients.

This study aimed to investigate the pharmacokinetics and target attainment of meropenem and compare the effect of meropenem dosing regimens in critically ill patients. Thirty-seven critically ill patients who were administered meropenem in intensive care units were analyzed. Patients were classified according to their renal function. Pharmacokinetic parameters were assessed based on Bayesian estimation. The target attainment of 40%fT > MIC (fraction time that the free concentration exceeds the minimum inhibitory concentration) and 100%fT > MIC with the pathogen MIC of 2 mg/L and 8 mg/L were specially focused. Furthermore, the effects of standard dosing (1g meropenem, 30 min intravenous infusion every 8h) and non-standard dosing (dosage regimens except standard dosing) were compared. The results showed that the values of meropenem clearance (CL), central volume of distribution (V1), intercompartmental clearance (Q), and peripheral volume of distribution (V2) were 3.3 L/h, 9.2 L, 20.1 L/h and 12.8 L, respectively. The CL of the patients among renal function groups was significantly different (p < 0.001). The tow targets attainment for the pathogen MIC of 2 mg/L and 8 mg/L were 89%, 73%, 49% and 27%, respectively. The severe renal impairment group has higher fraction of target attainment than the other group. The standard dosing achieved the target of 40%fT > 2/8 mg/L (85.7% and 81%, respectively) and patients with severe renal impairment achieved the target fraction of 100% for 40%fT > MIC. Additionally, there was no significant difference between standard and non-standard dosing group in target attainment. Our findings indicate that renal function is an important covariate for both meropenem pharmacokinetics parameters and target attainment. The target attainment between standard and non-standard dosing group was not comparable. Therefore, therapeutic drug monitoring is indispensable in the dosing adjustment for critically ill patients if it is available.

Population pharmacokinetics of meropenem in patients undergoing automated peritoneal dialysis.

Meropenem is a second-line agent for the treatment of peritoneal dialysis-associated peritonitis (PD peritonitis), while information on pharmacokinetics (PK) of intraperitoneal (i.p.) meropenem is limited in this patient group. The objective of the present evaluation was to assess a pharmacokinetic rationale for the selection of meropenem doses in automated PD (APD) patients based on population PK modelling. Data were available from a PK study in six patients undergoing APD who received a single 500 mg dose of meropenem intravenous or i.p. A population PK model was developed for plasma and dialysate concentrations (n = 360) using Monolix. Monte Carlo simulations were carried out to assess the probability of achieving meropenem concentrations above minimum inhibitory concentrations (MICs) of 2 and 8 mg/L, representing susceptible and less susceptible pathogens respectively, for at least 40% of the dosing interval (T >MIC ≥ 40%). A two-compartment model for each plasma and dialysate concentrations with one transit compartment for the transfer from plasma to dialysate fluid described the data well. An i.p. dose of 250 and 750 mg, for an MIC of 2 and 8 mg/L respectively, was sufficient to attain the pharmacokinetic/pharmacodynamic target (T >MIC ≥ 40%) in more than 90% patients in plasma and dialysate. Additionally, the model predicted that no relevant meropenem accumulation in plasma and/or peritoneal fluid would occur with prolonged treatment. Our results suggest that an i.p. dose of 750 mg daily is optimal for pathogens with an MIC 2-8 mg/L in APD patients.

Transdermal Detection of MB-102 and Correlation to Meropenem Pharmacokinetics During Continuous Renal Replacement Therapy: In Vivo Results.

Critically ill patients undergoing continuous renal replacement therapy (CRRT) have medical conditions requiring extensive pharmacotherapy. Continuous renal replacement therapy impacts drug disposition. Few data exist regarding drug dosing requirements with contemporary CRRT modalities and effluent rates. The practical limitations of pharmacokinetic studies requiring numerous plasma and effluent samples, and lack of generalizability of observations from specific CRRT prescriptions, highlight gaps in bedside assessment of CRRT drug elimination and individualized dosing needs. We employed a porcine model using transdermal fluorescence detection of the glomerular filtration rate fluorescent tracer agent MB-102, with the aim to assess the relationship between systemic exposure of MB-102 and meropenem during CRRT. Animals underwent bilateral nephrectomies and received intravenous bolus doses of MB-102 and meropenem. Once MB-102 equilibrated in the animal, CRRT was initiated. Continuous renal replacement therapy prescriptions comprised four combinations of blood pump (low versus high) and effluent (low versus high) flow rates. Changes in transdermal detected MB-102 clearance occurred immediately with a change in CRRT rates. Blood side meropenem clearance mirrored transdermal MB-102 clearance (r2: 0.95-0.97, p value all <0.001). We suggest transdermal MB-102 clearance provides real-time personalized assessment of drug elimination and could optimize prescription of drugs for critically ill patients requiring CRRT.

Does Cytokine-Release Syndrome Induced by CAR T-Cell Treatment Have an Impact on the Pharmacokinetics of Meropenem and Piperacillin/Tazobactam in Patients with Hematological Malignancies? Findings from an Observational Case-Control Study.

Chimeric antigen receptor (CAR) T-cell therapy is a promising approach for some relapse/refractory hematological B-cell malignancies; however, in most patients, cytokine release syndrome (CRS) may occur. CRS is associated with acute kidney injury (AKI) that may affect the pharmacokinetics of some beta-lactams. The aim of this study was to assess whether the pharmacokinetics of meropenem and piperacillin may be affected by CAR T-cell treatment. The study included CAR T-cell treated patients (cases) and oncohematological patients (controls), who were administered 24-h continuous infusion (CI) meropenem or piperacillin/tazobactam, optimized by therapeutic drug monitoring, over a 2-year period. Patient data were retrospectively retrieved and matched on a 1:2 ratio. Beta-lactam clearance (CL) was calculated as CL = daily dose/infusion rate. A total of 38 cases (of whom 14 and 24 were treated with meropenem and piperacillin/tazobactam, respectively) was matched with 76 controls. CRS occurred in 85.7% (12/14) and 95.8% (23/24) of patients treated with meropenem and piperacillin/tazobactam, respectively. CRS-induced AKI was observed in only 1 patient. CL did not differ between cases and controls for both meropenem (11.1 vs. 11.7 L/h, p = 0.835) and piperacillin (14.0 vs. 10.4 L/h, p = 0.074). Our findings suggest that 24-h CI meropenem and piperacillin dosages should not be reduced a priori in CAR T-cell patients experiencing CRS.