Comparison of piperacillin plasma concentrations in a prospective randomised trial of extended infusion versus intermittent bolus of piperacillin/tazobactam in paediatric patients

Spanish Society of Hospital Pharmacy and the Spanish Society of Pediatric Infectious Diseases (SEFH-SEIP) National Consensus Guidelines for therapeutic drug monitoring of antibiotic and antifungal drugs in pediatric and newborn patients

Therapeutic monitoring of antibiotics and antifungals based on pharmacokinetic and pharmacodynamic parameters, is a strategy increasingly used for the optimization of therapy to improve efficacy, reduce the occurrence of toxicities, and prevent the selection of antimicrobial resistance, particularly in vulnerable patients including neonates and the critical or immunocompromised host. In neonates and children, infections account for a high percentage of hospital admissions and anti-infectives are the most used drugs. However, pediatric pharmacokinetic and pharmacodynamic studies and the evidence regarding the efficacy and safety of some newly marketed antibiotics and antifungals -usually used off-label in pediatrics- to determine the optimal drug dosage regimens are limited. It is widely known that this population presents important differences in the pharmacokinetic parameters (especially in drug clearance and volume of distribution) in comparison with adults that may alter antimicrobial exposure and, therefore, compromise treatment success. In addition, pediatric patients are more susceptible to potential adverse drug effects and they need closer monitoring. The aim of this document, developed jointly between the Spanish Society of Hospital Pharmacy (SEFH) and the Spanish Society of Pediatric Infectious Diseases (SEIP), is to describe the available evidence on the indications for therapeutic drug monitoring of antibiotics and antifungals in newborn and pediatric patients and to provide practical recommendations for therapeutic drug monitoring in routine clinical practice to optimize pharmacokinetic and pharmacodynamic parameters, efficacy and safety of antibiotics and antifungals in the pediatric population.

[Translated article] Therapeutic Drug Monitoring of antibiotic and antifungical drugs in paediatric and newborn patients. Consensus Guidelines of the Spanish Society of Hospital Pharmacy (SEFH) and the Spanish Society of Paediatric Infectious Diseases (SEIP)

Therapeutic monitoring of antibiotics and antifungals based on pharmacokinetic and pharmacodynamic (PK/PD) parameters is a strategy increasingly used for the optimization of therapy to improve efficacy, reduce the occurrence of toxicities, and prevent the selection of antimicrobial resistance, particularly in vulnerable patients including neonates and the critical or immunocompromised paediatric host. In neonates and children, infections account for a high percentage of hospital admissions, and anti-infectives are the most used drugs. However, paediatric PK/PD studies and the evidence regarding the efficacy and safety of some newly marketed antibiotics and antifungals-usually used off-label in paediatrics-to determine the optimal drug dosage regimens are limited. It is widely known that this population presents important differences in the PK parameters (especially in drug clearance and volume of distribution) in comparison with adults that may alter antimicrobial exposure and, therefore, compromise treatment success. In addition, paediatric patients are more susceptible to potential adverse drug effects and they need closer monitoring. The aim of this document, developed jointly by the Spanish Society of Hospital Pharmacy and the Spanish Society of Paediatric Infectious Diseases, is to describe the available evidence on the indications for therapeutic drug monitoring (TDM) of antibiotics and antifungals in newborn and paediatric patients, and to provide practical recommendations for TDM in routine clinical practice to optimise their dosing, efficacy and safety. Of antibiotics and antifungals in the paediatric population.

Piperacillin/tazobactam treatment in children: evidence of subtherapeutic concentrations

Objective

Piperacillin/tazobactam (PIP/TAZ) is used for the treatment of lower respiratory tract bacterial infections in children. This study was performed to evaluate if the current dosing regimen results in therapeutic drug concentrations.

Patients and methods

Patients suspected or proven to have lower respiratory tract bacterial infection and administrated PIP/TAZ intravenously for a duration of no less than 0.5 h, q6h-q12h daily, were enrolled. Blood samples were collected, and PIP concentrations were determined by high-performance liquid chromatography. The individual predicted concentration of PIP was evaluated using the individual empirical Bayesian estimate method. The evaluated PK/PD targets included (1) 70% time when the predicted free drug concentration exceeds the minimum inhibitory concentration (fT > MIC) and (2) 50% fT > 4× MIC. Probability of target attainment (PTA) was assessed by the proportion of patients who reached the PK/PD targets. The PIP concentrations between different groups of patients were compared.

Results

A total of 57 samples were collected from 57 patients with a median age of 2.26 years (0.17-12.58). For the PK/PD targets of 70% fT > MIC and 50% fT > 4× MIC for Pseudomonas aeruginosa and Klebsiella pneumoniae, the PTA was all 0. The median Cmin of PIP was significantly higher in infants than in children, and the median Cmin after administration in q8h was significantly higher than that after administration in q12h.

Conclusion

The current dose regimen of PIP/TAZ leads to extremely low plasma concentrations in most children with lower respiratory tract bacterial infections. More optimized dosing regimens or better alternative therapies need to be further explored.

Defining the pharmacokinetic/pharmacodynamic index of piperacillin/tazobactam within a hollow-fibre infection model to determine target attainment in intensive care patients

Background

It is important to optimize dosing schemes of antibiotics to maximize the probability of therapeutic success. The recommended pharmacokinetic/pharmacodynamic (PK/PD) index for piperacillin/tazobactam therapy in clinical studies ranges widely (50%-100% fT>1-4×MIC). Dosing schemes failing to achieve PK/PD targets may lead to negative treatment outcomes.

Objectives

The first aim of this study was to define the optimal PK/PD index of piperacillin/tazobactam with a hollow-fibre infection model (HFIM). The second aim was to predict whether these PK/PD targets are currently achieved in critically ill patients through PK/PD model simulation.

Patients and methods

A dose-fractionation study comprising 21 HFIM experiments was performed against a range of Gram-negative bacterial pathogens, doses and infusion times. Clinical data and dose histories from a case series of nine patients with a known bacterial infection treated with piperacillin/tazobactam in the ICU were collected. The PK/PD index and predicted plasma concentrations and therefore target attainment of the patients were simulated using R version 4.2.1.

Results

fT >MIC was found to be the best-fitting PK/PD index for piperacillin/tazobactam. Bactericidal activity with 2 log10 cfu reduction was associated with 77% fT>MIC. Piperacillin/tazobactam therapy was defined as clinically 'ineffective' in ∼78% (7/9) patients. Around seventy-one percent (5/7) of these patients had a probability of >10% that 2  log10 cfu reduction was not attained.

Conclusions

Our dose-fractionation study indicates an optimal PK/PD target in piperacillin/tazobactam therapies should be 77% fT>MIC for 2 log10 kill. Doses to achieve this target should be considered when treating patients in ICU.

Extended Infusion of Beta-Lactams and Glycopeptides: A New Era in Pediatric Care? A Systematic Review and Meta-Analysis

Optimizing antibiotic therapy is imperative with rising bacterial resistance and high infection mortality. Extended infusion defined as a continuous infusion (COI) or prolonged infusion (PI) of beta-lactams and glycopeptides might improve efficacy and safety compared to their intermittent administration (IA). This study aimed to evaluate the efficacy and safety of extended infusion in pediatric patients. Adhering to Cochrane standards, we conducted a systematic review with meta-analysis investigating the efficacy and safety of COI (24 h/d) and PI (>1 h/dose) compared to IA (≤1 h/dose) of beta-lactams and glycopeptides in pediatrics. Primary outcomes included mortality, clinical success, and microbiological eradication. Five studies could be included for the outcome mortality, investigating meropenem, piperacillin/tazobactam, cefepime, or combinations of these. The pooled relative risk estimate was 0.48 (95% CI 0.26-0.89, p = 0.02). No significant differences between the administration modes were found for the outcomes of clinical success, microbiological eradication (beta-lactams; glycopeptides), and mortality (glycopeptides). No study reported additional safety issues, e.g., adverse drug reactions when using COI/PI vs. IA. Our findings suggest that the administration of beta-lactams by extended infusion leads to a reduction in mortality for pediatric patients.

Extended infusion of β-lactams significantly reduces mortality and enhances microbiological eradication in paediatric patients: a systematic review and meta-analysis

Background

Paediatric patients are often exposed to subtherapeutic levels or treatment failure of β-lactams, and prolonged infusion may be beneficial. We aimed to investigate the efficacy and safety of extended infusion (EI; defined as ≥3 h) or continuous infusion vs. short, intermittent infusion (SI; defined as ≤60 min) of β-lactams in patients <21 years of age.

Methods

A systematic review and meta-analysis was conducted to compare EI and continuous infusion with SI of β-lactams in children. A systematic search was performed in MEDLINE (via PubMed), Embase, CENTRAL, and Scopus databases for randomised controlled trials (RCTs) and observational studies published from database inception up to August 22, 2023. Any comparative study concerned with mortality, clinical efficacy, adverse events, or plasma concentrations of β-lactams for any infection was eligible. Case reports, case series, and patients aged >21 years were excluded. Odds ratios (OR) and median differences with 95% confidence intervals (CI) were calculated using a random-effects model. Risk of bias (ROB) was assessed using ROB2 and ROBINS-I tools. The protocol was registered with PROSPERO, CRD42022375397.

Findings

In total, 19,980 articles were screened, out of which 19 studies (4195 patients) were included in the meta-analysis. EI administration was associated with a significantly lower all-cause mortality in both RCTs and non-RCTs [OR 0.74; CI 0.55-0.99; I2 = 0%; CI 0-58%]. Early microbiological eradication was higher with EI [OR 3.18; CI 2.24-4.51; I2 = 0%; CI 0-90%], but the clinical cure did not differ significantly between the two groups [OR 1.20; CI 0.17-8.71; I2 = 79%; CI 32-93%]. Achieving the optimal plasma level (50-100% fT > MIC) appeared favourable in the EI group compared to the SI. No significant differences were observed in the adverse events. The overall ROB was high because of the small sample sizes and clinically heterogeneous populations.

Interpretation

Our findings suggest that extended infusion of β-lactams was associated with lower mortality and increased microbiological eradication and was considered safe compared to short-term infusion.

Funding

None.

Model-informed precision dosing of antimicrobial drugs in pediatrics: experiences from a pilot scale program

Antibiotics are among the most utilized drugs in pediatrics. Nonetheless, there is a lack in pharmacokinetics information for this population, and dosing criteria may vary between healthcare centers. Physiological variability associated with maturation in pediatrics makes it challenging to reach a consensus on adequate dosing, which is further accentuated in more vulnerable groups, such as critically ill or oncology patients. Model-informed precision dosing is a useful practice that allows dose optimization and attainment of antibiotic-specific pharmacokinetic/pharmacodynamic targets. The aim of this study was to evaluate the needs of model-informed precision dosing of antibiotics in a pediatrics unit, at a pilot scale. Pediatric patients under antibiotic treatment were monitored with either a pharmacokinetic/pharmacodynamic optimized sampling scheme or through opportunistic sampling. Clindamycin, fluconazole, linezolid, meropenem, metronidazole, piperacillin, and vancomycin plasma concentrations were quantified through a liquid chromatography coupled to mass spectrometry method. Pharmacokinetic parameters were estimated using a Bayesian approach to verify pharmacokinetic/pharmacodynamic target attainment. A total of 23 pediatric patients aged 2 to 16 years were included, and 43 dosing regimens were evaluated; 27 (63%) of them required adjustments as follows: 14 patients were underdosed, 4 were overdosed, and 9 patients needed infusion rate adjustments. Infusion rate adjustments were mostly recommended for piperacillin and meropenem; daily doses were augmented for vancomycin and metronidazole, meanwhile linezolid was adjusted for under- and overdosing. Clindamycin and fluconazole regimens were not adjusted at all.  Conclusion: Results showcase a lack of antibiotic pharmacokinetic/pharmacodynamic target attainment (particularly for linezolid, vancomycin, meropenem, and piperacillin), and the need for model-informed precision dosing in pediatrics. This study provides pharmacokinetic evidence which can further improve antibiotic dosing practices. What is Known: • Model-informed precision dosing is performed in pediatrics to optimize the treatment of antimicrobial drugs such as vancomycin and aminoglycosides, while its usefulness is debated for other groups (beta-lactams, macrolides, etc.). What is New: • Vulnerable pediatric subpopulations, such as critically ill or oncology patients, can benefit the most from model-informed precision dosing of antibiotics. • Model-informed precision dosing of linezolid, meropenem, piperacillin, and vancomycin is particularly useful in pediatrics, and further research may improve dosing practices altogether.

Therapeutic drug monitoring of meropenem and pharmacokinetic-pharmacodynamic target assessment in critically ill pediatric patients from a prospective observational study

OBJECTIVES

To compare the unbound plasma meropenem concentrations at mid-dosing intervals (C_mid, 50%fT), end-dosing intervals (C_trough, 100%fT), and proportions of patients achieving 50%fT and 100%fT above MIC (50%fT_>MIC and 100%fT_>MIC) between extended infusion (EI) and intermittent bolus (IB) administration in a therapeutic drug monitoring (TDM) program in children.

METHODS

A prospective observational study was conducted in children aged 1 month to 18 years receiving meropenem every 8 h by either EI or IB. Meropenem C_mid, C_trough, and proportions of patients achieving 50%fT_>MIC and 100%fT_>MIC were compared.

RESULTS

TDM data from 72 patients with a median age (IQR) of 12 months (3-37) were used. Meropenem dose was 120 and 60 mg/kg/day in EI and IB groups, respectively. Geometric mean (95% CI) C_mid of EI versus IB was 17.3 mg/L (13.7-21.8) versus 3.4 mg/L (1.7-6.7) (P<0.001). Geometric mean (95% CI) C_trough of EI versus IB was 2.3 mg/L (1.6-3.4) versus 0.8 mg/L (0.4-1.5) (P=0.005). Greater proportions of patients achieving 50%fT_>MIC and 100%fT_>MIC were observed in the EI group.

CONCLUSIONS

A meropenem dose of 20 mg/kg/dose given by IB should not be used in critically ill children, even if they are not suspected of having a CNS infection. A dose of 40 mg/kg/dose given by EI resulted in higher C_mid, C_trough, and proportions of patients achieving 50%fT_>MIC and 100%fT_>MIC.

Beta-Lactams Therapeutic Monitoring in Septic Children-What Target Are We Aiming for? A Scoping Review

The antimicrobial therapy of sepsis and septic shock should be individualized based on pharmacokinetic/pharmacodynamic (PK/PD) parameters to deliver effective and timely treatment of life-threatening infections. We conducted a literature scoping review to identify therapeutic targets of beta-lactam antibiotics in septic pediatric patients and the strategies that have been applied to overcome sepsis-related altered pharmacokinetics and increase target attainment against susceptible pathogens. A systematic search was conducted in the MEDLINE, EMBASE and Web of Science databases to select studies conducted since 2010 with therapeutic monitoring data of beta-lactams in septic children. Last searches were performed on 02 September 2021. Two independent authors selected the studies and extracted the data. A narrative and qualitative approach was used to summarize the findings. Out of the 118 identified articles, 21 met the eligibility criteria. Population pharmacokinetic modeling was performed in 12 studies, while nine studies reported data from bedside monitoring of beta-lactams. Most studies were conducted in the United States of America (n = 9) and France (n = 5) and reported PK/PD data of amoxicillin, ampicillin, azlocillin, aztreonam, cefazolin, cefepime, cefotaxime, ceftaroline, ceftazidime, doripenem, meropenem and piperacillin/tazobactam. Therapeutic targets ranged from to 40% fT> MIC to 100% fT> 6 × MIC. Prolonging the infusion time and frequency were most described strategies to increase target attainment. Monitoring beta-lactam serum concentrations in clinical practice may potentially maximize therapeutic target attainment. Further studies are required to define the therapeutic target associated with the best clinical outcomes.