Development of a dosing algorithm for meropenem in critically ill patients based on a population pharmacokinetic/pharmacodynamic analysis

Introduction: optimal treatment of Gram-negative infections in critically ill patients is challenged by changing pathophysiological conditions, reduced antimicrobial susceptibility and limited therapeutic options. The aim of this study was to assess the impact of maximizing Css/MIC ratio on efficacy of continuous infusion (CI) meropenem in treating documented Gram-negative infections in critically ill patients and to perform a population pharmacokinetic/pharmacodynamic analysis to support treatment optimization.Materials and Methods: Classification and regression tree (CART) analysis was used to identify whether a cutoff of steady-state meropenem concentration (Css)-to-minimum inhibitory concentration (MIC) (Css/MIC) ratio correlated with favorable clinical outcome. A non-parametric approach with Pmetrics was used for pharmacokinetic analysis and covariate evaluation. The probability of target attainment (PTA) of the identified Css/MIC ratio was calculated by means of Monte Carlo simulations. Cumulative fraction of response (CFRs) were calculated against common Enterobacterales, P. aeruginosa and A. baumannii as well.Results: a total of 74 patients with 183 meropenem Css were included. CART analysis identified a Css/MIC ratio ≥4.63 as cutoff value significantly associated with favorable clinical outcomes. Multivariate regression analysis confirmed the association [OR (95%CI): 20.440 (2.063–202.522); p < 0.01]. Creatinine clearance (CLCR) was the only covariate associated with meropenem clearance. Monte Carlo simulations showed that, across different classes of renal function, dosages of meropenem ranging between 0.5 and 2 g q6h over 6 h (namely by CI) may grant PTAs of Css/MIC ratios ≥4.63 against susceptible pathogens with an MIC up to the EUCAST clinical breakpoint of 2 mg/L. The CFRs achievable with these dosages were very high (>90%) against Enterobacterales across all the classes of renal function and against P. aeruginosa among patients with CLCR < 30 ml/min/1.73 m2, and quite lower against A. baumannii.Discussion: our findings suggest that Css/MIC ratio ≥4.63 may be considered the pharmacodynamic target useful at maximizing the efficacy of CI meropenem in the treatment of Gram-negative infections in critically ill patients. Dosages ranging between 0.5 g q6h and 2 g q6h by CI may maximize the probability of favorable clinical outcome against meropenem-susceptible Gram-negative pathogens among critically ill patients having different degrees of renal function.

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Novel Population Pharmacokinetic Model for Linezolid in Critically Ill Patients and Evaluation of the Adequacy of the Current Dosing Recommendation

Pharmaceutics ◽

10.3390/pharmaceutics12010054 ◽

2020 ◽

Vol 12 (1) ◽

pp. 54 ◽

Cited By ~ 2

Author(s):

Amaia Soraluce ◽

Helena Barrasa ◽

Eduardo Asín-Prieto ◽

Jose Ángel Sánchez-Izquierdo ◽

Javier Maynar ◽

...

Keyword(s):

Critically Ill ◽

Critically Ill Patients ◽

Population Pharmacokinetic Model ◽

Pharmacokinetic Model ◽

Standard Dose ◽

Compartment Model ◽

Antimicrobial Treatment ◽

Population Pharmacokinetic ◽

Renal Replacement Therapies ◽

Continuous Renal Replacement Therapies

Antimicrobial treatment in critically ill patients remains challenging. The aim of this study was to develop a population pharmacokinetic model for linezolid in critically ill patients and to evaluate the adequacy of current dosing recommendation (600 mg/12 h). Forty inpatients were included, 23 of whom were subjected to continuous renal replacement therapies (CRRT). Blood and effluent samples were drawn after linezolid administration at defined time points, and linezolid levels were measured. A population pharmacokinetic model was developed, using NONMEM 7.3. The percentage of patients that achieved the pharmacokinetic/pharmacodynamic (PK/PD) targets was calculated (AUC24/MIC > 80 and 100% T>MIC). A two-compartment model best described the pharmacokinetics of linezolid. Elimination was conditioned by the creatinine clearance and by the extra-corporeal clearance if the patient was subjected to CRRT. For most patients, the standard dose of linezolid did not cover infections caused by pathogens with MIC ≥ 2 mg/L. Continuous infusion may be an alternative, especially when renal function is preserved.

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Influence of Mechanical Ventilation on the Pharmacokinetics of Vancomycin Administered by Continuous Infusion in Critically Ill Patients

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01249-17 ◽

2017 ◽

Vol 61 (12) ◽

Cited By ~ 9

Author(s):

Susanna Edith Medellín-Garibay ◽

Silvia Romano-Moreno ◽

Pilar Tejedor-Prado ◽

Noelia Rubio-Álvaro ◽

Aida Rueda-Naharro ◽

...

Keyword(s):

Mechanical Ventilation ◽

Creatinine Clearance ◽

Continuous Infusion ◽

Critically Ill ◽

Critically Ill Patients ◽

Population Pharmacokinetic Model ◽

Pharmacokinetic Model ◽

Volume Of Distribution ◽

Stochastic Simulations ◽

Population Pharmacokinetic

ABSTRACT Pathophysiological changes involved in drug disposition in critically ill patients should be considered in order to optimize the dosing of vancomycin administered by continuous infusion, and certain strategies must be applied to reach therapeutic targets on the first day of treatment. The aim of this study was to develop a population pharmacokinetic model of vancomycin to determine clinical covariates, including mechanical ventilation, that influence the wide variability of this antimicrobial. Plasma vancomycin concentrations from 54 critically ill patients were analyzed simultaneously by a population pharmacokinetic approach. A nomogram for dosing recommendations was developed and was internally evaluated through stochastic simulations. The plasma vancomycin concentration-versus-time data were best described by a one-compartment open model with exponential interindividual variability associated with vancomycin clearance and the volume of distribution. Residual error followed a homoscedastic trend. Creatinine clearance and body weight significantly dropped the objective function value, showing their influence on vancomycin clearance and the volume of distribution, respectively. Characterization based on the presence of mechanical ventilation demonstrated a 20% decrease in vancomycin clearance. External validation (n = 18) was performed to evaluate the predictive ability of the model; median bias and precision values were 0.7 mg/liter (95% confidence interval [CI], −0.4, 1.7) and 5.9 mg/liter (95% CI, 5.4, 6.4), respectively. A population pharmacokinetic model was developed for the administration of vancomycin by continuous infusion to critically ill patients, demonstrating the influence of creatinine clearance and mechanical ventilation on vancomycin clearance, as well as the implications for targeting dosing rates to reach the therapeutic range (20 to 30 mg/liter).

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Population Pharmacokinetic Analysis of Colistin Methanesulfonate and Colistin after Intravenous Administration in Critically Ill Patients with Infections Caused by Gram-Negative Bacteria

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01361-08 ◽

2009 ◽

Vol 53 (8) ◽

pp. 3430-3436 ◽

Cited By ~ 333

Author(s):

D. Plachouras ◽

M. Karvanen ◽

L. E. Friberg ◽

E. Papadomichelakis ◽

A. Antoniadou ◽

...

Keyword(s):

Steady State ◽

Critically Ill ◽

Critically Ill Patients ◽

Compartment Model ◽

Population Pharmacokinetic Analysis ◽

Pharmacokinetic Analysis ◽

Population Pharmacokinetic ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Colistin Methanesulfonate

ABSTRACT Colistin is used to treat infections caused by multidrug-resistant gram-negative bacteria (MDR-GNB). It is administered intravenously in the form of colistin methanesulfonate (CMS), which is hydrolyzed in vivo to the active drug. However, pharmacokinetic data are limited. The aim of the present study was to characterize the pharmacokinetics of CMS and colistin in a population of critically ill patients. Patients receiving colistin for the treatment of infections caused by MDR-GNB were enrolled in the study; however, patients receiving a renal replacement therapy were excluded. CMS was administered at a dose of 3 million units (240 mg) every 8 h. Venous blood was collected immediately before and at multiple occasions after the first and the fourth infusions. Plasma CMS and colistin concentrations were determined by a novel liquid chromatography-tandem mass spectrometry method after a rapid precipitation step that avoids the significant degradation of CMS and colistin. Population pharmacokinetic analysis was performed with the NONMEM program. Eighteen patients (6 females; mean age, 63.6 years; mean creatinine clearance, 82.3 ml/min) were included in the study. For CMS, a two-compartment model best described the pharmacokinetics, and the half-lives of the two phases were estimated to be 0.046 h and 2.3 h, respectively. The clearance of CMS was 13.7 liters/h. For colistin, a one-compartment model was sufficient to describe the data, and the estimated half-life was 14.4 h. The predicted maximum concentrations of drug in plasma were 0.60 mg/liter and 2.3 mg/liter for the first dose and at steady state, respectively. Colistin displayed a half-life that was significantly long in relation to the dosing interval. The implications of these findings are that the plasma colistin concentrations are insufficient before steady state and raise the question of whether the administration of a loading dose would benefit critically ill patients.

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Population Pharmacokinetics of Piperacillin following Continuous Infusion in Critically Ill Patients and Impact of Renal Function on Target Attainment

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02556-19 ◽

2020 ◽

Vol 64 (7) ◽

Author(s):

Vibeke Klastrup ◽

Anders Thorsted ◽

Merete Storgaard ◽

Steffen Christensen ◽

Lena E. Friberg ◽

...

Keyword(s):

Continuous Infusion ◽

Critically Ill ◽

Critically Ill Patients ◽

Bacterial Infections ◽

Population Pharmacokinetic ◽

Target Attainment ◽

Content Type ◽

Daily Dose ◽

Linear Elimination ◽

Severe Infections

ABSTRACT Pharmacokinetic changes are often seen in patients with severe infections. Administration by continuous infusion has been suggested to optimize antibiotic exposure and pharmacokinetic/pharmacodynamic (PK/PD) target attainment for β-lactams. In an observational study, unbound piperacillin concentrations (n = 196) were assessed in 78 critically ill patients following continuous infusion of piperacillin-tazobactam (ratio 8:1). The initial dose of 8, 12, or 16 g (piperacillin component) was determined by individual creatinine clearance (CRCL). Piperacillin concentrations were compared to the EUCAST clinical breakpoint MIC for Pseudomonas aeruginosa (16 mg/liter), and the following PK/PD targets were evaluated: 100% free time (fT) > 1× MIC and 100% fT > 4× MIC. A population pharmacokinetic model was developed using NONMEM 7.4.3 consisting of a one-compartment disposition model with linear elimination separated into nonrenal and renal (linearly increasing with patient CRCL) clearances. Target attainment was predicted and visualized for all individuals based on the utilized CRCL dosing algorithm. The target of 100% fT > 1× MIC was achieved for all patients based on the administered dose, but few patients achieved the target of 100% fT > 4× MIC. Probability of target attainment for a simulated cohort of patients showed that increasing the daily dose by 4-g increments (piperacillin component) did not result in substantially improved target attainment for the 100% fT > 4× MIC target. To conclude, in patients with high CRCL combined with high-MIC bacterial infections, even a continuous infusion (CI) regimen with a daily dose of 24 g may be insufficient to achieve therapeutic concentrations.

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Population Pharmacokinetic Study of the Suitability of Standard Dosing Regimens of Amikacin in Critically Ill Patients with Open-Abdomen and Negative-Pressure Wound Therapy

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02098-19 ◽

2020 ◽

Vol 64 (4) ◽

Author(s):

Cédric Carrié ◽

Faustine Delzor ◽

Stéphanie Roure ◽

Vincent Dubuisson ◽

Laurent Petit ◽

...

Keyword(s):

Monte Carlo ◽

Body Weight ◽

Monte Carlo Simulations ◽

Critically Ill ◽

Negative Pressure ◽

Critically Ill Patients ◽

Open Abdomen ◽

Population Pharmacokinetic ◽

Pressure Therapy ◽

Dosing Regimens

ABSTRACT The aim was to assess the appropriateness of recommended regimens for empirical MIC coverage in critically ill patients with open-abdomen and negative-pressure therapy (OA/NPT). Over a 5-year period, every critically ill patient who received amikacin and who underwent therapeutic drug monitoring (TDM) while being treated by OA/NPT was retrospectively included. A population pharmacokinetic (PK) modeling was performed considering the effect of 10 covariates (age, sex, total body weight [TBW], adapted body weight [ABW], body surface area [BSA], modified sepsis-related organ failure assessment [SOFA] score, vasopressor use, creatinine clearance [CLCR], fluid balance, and amount of fluids collected by the NPT over the sampling day) in patients who underwent continuous renal replacement therapy (CRRT) or did not receive CRRT. Monte Carlo simulations were employed to determine the fractional target attainment (FTA) for the PK/pharmacodynamic [PD] targets (maximum concentration of drug [Cmax]/MIC ratio of ≥8 and a ratio of the area under the concentration-time curve from 0 to 24 h [AUC0–24]/MIC of ≥75). Seventy critically ill patients treated by OA/NPT (contributing 179 concentration values) were included. Amikacin PK concentrations were best described by a two-compartment model with linear elimination and proportional residual error, with CLCR and ABW as significant covariates for volume of distribution (V) and CLCR for CL. The reported V) in non-CRRT and CRRT patients was 35.8 and 40.2 liters, respectively. In Monte Carlo simulations, ABW-adjusted doses between 25 and 35 mg/kg were needed to reach an FTA of >85% for various renal functions. Despite an increased V and a wide interindividual variability, desirable PK/PD targets may be achieved using an ABW-based loading dose of 25 to 30 mg/kg. When less susceptible pathogens are targeted, higher dosing regimens are probably needed in patients with augmented renal clearance (ARC). Further studies are needed to assess the effect of OA/NPT on the PK parameters of antimicrobial agents.

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Evaluation of an Intravenous Potassium Dosing Algorithm for Hypokalemic Critically Ill Patients

Journal of Parenteral and Enteral Nutrition ◽

10.1177/0148607115602885 ◽

2015 ◽

Vol 41 (5) ◽

pp. 796-804 ◽

Cited By ~ 1

Author(s):

Corry T. Johnston ◽

George O. Maish ◽

Gayle Minard ◽

Martin A. Croce ◽

Roland N. Dickerson

Keyword(s):

Critically Ill ◽

Critically Ill Patients ◽

Dosing Algorithm

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New Colistin Population Pharmacokinetic Data in Critically Ill Patients Suggesting an Alternative Loading Dose Rationale

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03508-14 ◽

2014 ◽

Vol 58 (12) ◽

pp. 7324-7330 ◽

Cited By ~ 50

Author(s):

N. Grégoire ◽

O. Mimoz ◽

B. Mégarbane ◽

E. Comets ◽

D. Chatelier ◽

...

Keyword(s):

Steady State ◽

Critically Ill ◽

Critically Ill Patients ◽

Plasma Concentrations ◽

Multidrug Resistant ◽

Pharmacokinetic Analysis ◽

Population Pharmacokinetic ◽

Pharmacokinetic Data ◽

Loading Dose ◽

Liquid Chromatography Tandem Mass

ABSTRACTColistin is an old antibiotic that has recently gained a considerable renewal of interest as the last-line defense therapy against multidrug-resistant Gram-negative bacteria. It is administered as colistin methanesulfonate (CMS), an inactive prodrug, and it was shown that due to slow CMS conversion, colistin plasma concentrations increase very slowly after treatment initiation, which constitutes the rationale for a loading dose in critically ill patients. However, faster CMS conversion was observed in healthy volunteers but using a different CMS brand, which may also have a major impact on colistin pharmacokinetics. Seventy-three critically ill patients not undergoing dialysis received multiple doses of CMS. The CMS concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and a pharmacokinetic analysis was conducted using a population approach. We confirmed that CMS renal clearance and colistin concentrations at steady state are mostly governed by creatinine clearance, but we predict a typical maximum concentration of drug in serum (Cmax) of colistin close to 2 mg/liter, occurring 3 h after an initial dose of 2 million international units (MIU) of CMS. Accordingly, the estimated colistin half-life (t1/2) was relatively short (3.1 h), with rapid attainment of steady state. Our results are only partially consistent with other recently published results. We confirm that the CMS maintenance dose should be adjusted according to renal function in critically ill patients. However, much higher than expected colistin concentrations were observed after the initial CMS dose, with rapid steady-state achievement. These discrepancies challenge the pharmacokinetic rationale for a loading dose, which may still be appropriate for rapid bacterial eradication and an improved clinical cure rate.

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