Comparing prolonged infusion to intermittent infusion strategies for beta-lactam antibiotics in patients with gram-negative bacterial infections: a systematic review and meta-analysis

INTRODUCTION

Our objective is to determine whether prolonged infusion (PI) of beta-lactam antibiotics yields superior outcomes compared to intermittent infusion (II) in patients with Gram-Negative Bacterial (GNB) infections.

METHODS

We systematically searched papers from PubMed, the Cochrane Library, Embase, and Clinicaltrials.gov, targeting mortality as the primary outcome and looking at the clinical cure rate, hospital and intensive care unit (ICU) stay lengths, antibiotic treatment duration, and mechanical ventilation (MV) duration as secondary outcomes.

RESULTS

Our meta-analysis of 18 studies, including 5 randomized control trials and 13 observational studies, with a total of 3,035 patients-1,510 in the PI group and 1,525 in the II group, revealed significant findings. PI was associated with reduced mortality (RR, 0.67; 95% CI, 0.55-0.81; p = 0.001; I2 = 4.52%) and a shorter MV duration (SMD, -0.76; 95% CI, -1.37 to -0.16; p = 0.01; I2 = 87.81%) compared to II. However, no differences were found in clinical cure rates, antibiotic treatment duration, length of hospital stay, or length of ICU stay.

CONCLUSIONS

The PI approach for administering beta-lactam antibiotics in patients with suspected or confirmed GNB infections may be advantageous in reducing mortality rates and the duration of MV when compared to the II strategy.

Physical compatibility of sulbactam/durlobactam with select intravenous drugs during simulated Y-site administration

PURPOSE

Sulbactam/durlobactam is a combination antibiotic designed to target Acinetobacter baumannii, including carbapenem-resistant and multidrug-resistant strains. The objective of this study was to determine the physical compatibility of sulbactam/durlobactam solution during simulated Y-site administration with 95 intravenous (IV) drugs.

METHODS

Vials of sulbactam/durlobactam solution were diluted in 0.9% sodium chloride injection to a volume of 100 mL (the final concentration of both drugs was 15 mg/mL). All other IV drugs were reconstituted according to the manufacturer's recommendations and diluted with 0.9% sodium chloride injection to the upper range of concentrations used clinically or tested undiluted as intended for administration. Y-site conditions were simulated by mixing 5 mL of sulbactam/durlobactam with 5 mL of the tested drug solutions in a 1:1 ratio. Solutions were inspected for physical characteristics (clarity, color, and Tyndall effect), turbidity, and pH changes before admixture, immediately post admixture, and over 4 hours. Incompatibility was defined as any observed precipitation, significant color change, positive Tyndall test, or turbidity change of ≥0.5 nephelometric turbidity unit during the observation period.

RESULTS

Sulbactam/durlobactam was physically compatible with 38 out of 42 antimicrobials tested (90.5%) and compatible overall with 86 of 95 drugs tested (90.5%). Incompatibility was observed with albumin, amiodarone hydrochloride, ceftaroline fosamil, ciprofloxacin, daptomycin, levofloxacin, phenytoin sodium, vecuronium, and propofol.

CONCLUSION

The Y-site compatibility of sulbactam/durlobactam with 95 IV drugs was described. These compatibility data will assist pharmacists and nurses to safely coordinate administration of IV medications with sulbactam/durlobactam.

Comparison of the Effectiveness of Prolonged Infusion and Intermittent Infusion of Meropenem in Patients With Sepsis: A Meta-Analysis

The aim of this study was to compare the clinical effectiveness of prolonged infusion and intermittent infusion of meropenem in patients with sepsis. This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 guidelines. PubMed, Web of Science, Scopus, and the Cochrane Library were searched without any language or time restrictions, up to September 25, 2023. The primary outcomes assessed in this meta-analysis included clinical success and all-cause mortality. Other outcomes assessed in this study encompassed the mean length of ICU stay. Total eight studies met the eligibility criteria and were included in this meta-analysis. Pooled analysis showed that the clinical success rate was significantly higher in patients receiving prolonged infusion of meropenem compared to intermittent infusion (RR: 1.49, 95% CI: 1.30 to 1.70). All-cause mortality was 24% significantly lower in patients receiving prolonged infusion of meropenem compared to intermittent infusion (RR: 0.76, 95% CI: 0.60 to 0.96). The results suggest that prolonged infusion of meropenem could be a more effective and efficient treatment for sepsis patients. However, more randomized controlled trials are needed to confirm these findings and to establish the optimal dosing and administration schedule for prolonged infusion of meropenem.

International consensus recommendations for the use of prolonged-infusion beta-lactam antibiotics: Endorsed by the American College of Clinical Pharmacy, British Society for Antimicrobial Chemotherapy, Cystic Fibrosis Foundation, European Society of Clinical Microbiology and Infectious Diseases, Infectious Diseases Society of America, Society of Critical Care Medicine, and Society of Infectious Diseases Pharmacists

Intravenous β-lactam antibiotics remain a cornerstone in the management of bacterial infections due to their broad spectrum of activity and excellent tolerability. β-lactams are well established to display time-dependent bactericidal activity, where reductions in bacterial burden are directly associated with the time that free drug concentrations remain above the minimum inhibitory concentration (MIC) of the pathogen during the dosing interval. In an effort to take advantage of these bactericidal characteristics, prolonged (extended and continuous) infusions (PIs) can be applied during the administration of intravenous β-lactams to increase time above the MIC. PI dosing regimens have been implemented worldwide, but implementation is inconsistent. We report consensus therapeutic recommendations for the use of PI β-lactams developed by an expert international panel with representation from clinical pharmacy and medicine. This consensus guideline provides recommendations regarding pharmacokinetic and pharmacodynamic targets, therapeutic drug-monitoring considerations, and the use of PI β-lactam therapy in the following patient populations: severely ill and nonseverely ill adult patients, pediatric patients, and obese patients. These recommendations provide the first consensus guidance for the use of β-lactam therapy administered as PIs and have been reviewed and endorsed by the American College of Clinical Pharmacy (ACCP), the British Society for Antimicrobial Chemotherapy (BSAC), the Cystic Fibrosis Foundation (CFF), the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), the Infectious Diseases Society of America (IDSA), the Society of Critical Care Medicine (SCCM), and the Society of Infectious Diseases Pharmacists (SIDP).

International consensus recommendations for the use of prolonged-infusion beta-lactam antibiotics: Endorsed by the American College of Clinical Pharmacy, British Society for Antimicrobial Chemotherapy, Cystic Fibrosis Foundation, European Society of Clinical Microbiology and Infectious Diseases, Infectious Diseases Society of America, Society of Critical Care Medicine, and Society of Infectious Diseases Pharmacists: An executive summary

Intravenous β-lactam antibiotics remain a cornerstone in the management of bacterial infections due to their broad spectrum of activity and excellent tolerability. β-lactams are well established to display time-dependent bactericidal activity, where reductions in bacterial burden are directly associated with the time that free drug concentrations remain above the minimum inhibitory concentration (MIC) of the pathogen during the dosing interval. In an effort to take advantage of these bactericidal characteristics, prolonged (extended and continuous) infusions (PI) can be applied during the administration of intravenous β-lactams to increase time above the MIC. PI dosing regimens have been implemented worldwide, but implementation is inconsistent. We report consensus therapeutic recommendations for the use of β-lactam PI developed by an expert international panel with representation from clinical pharmacy and medicine. This consensus guideline provides recommendations regarding pharmacokinetic and pharmacodynamic targets, therapeutic drug monitoring considerations, and the use of PI β-lactam therapy in the following patient populations: severely ill and nonseverely ill adult patients, pediatric patients, and obese patients. These recommendations provide the first consensus guidance for the use of β-lactam therapy administered as PIs and have been reviewed and endorsed by the American College of Clinical Pharmacy (ACCP), the British Society for Antimicrobial Chemotherapy (BSAC), the Cystic Fibrosis Foundation (CFF), the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), the Infectious Diseases Society of America (IDSA), the Society of Critical Care Medicine (SCCM), and the Society of Infectious Diseases Pharmacists (SIDP).

Efficacy of prolonged intravenous lidocaine infusion for postoperative movement-evoked pain following hepatectomy: a double-blinded, randomised, placebo-controlled trial

BACKGROUND

The analgesic effect of intravenous lidocaine varies with the duration of lidocaine infusion and surgery type. We tested the hypothesis that prolonged lidocaine infusion alleviates postoperative pain in patients recovering from hepatectomy over the first 3 postoperative days.

METHODS

Patients undergoing elective hepatectomy were randomly assigned to receive prolonged i.v. lidocaine treatment or placebo. The primary outcome was incidence of moderate-to-severe movement-evoked pain at 24 h postoperatively. The secondary outcomes included incidence of moderate-to-severe pain during movement and at rest throughout the first 3 postoperative days, postoperative opioid consumption, and pulmonary complications. Plasma lidocaine concentration was also monitored.

RESULTS

We enrolled 260 subjects. Intravenous lidocaine lowered the incidence of moderate-to-severe movement-evoked pain at 24 h and 48 h postoperatively (47.7% vs 67.7%, P=0.001; 38.5% vs 58.5%, P=0.001) and reduced movement-evoked pain scores (3.7 [1.7] vs 4.2 [1.6]; mean difference 0.5 [95% confidence interval {CI}: 0.1-0.9]; P=0.018) and morphine equivalent consumption (47.2 [16.7] mg vs 52.6 [19.2] mg; mean difference 5.4 mg [95% CI: 1.0-9.8]; P=0.016) at 24 h postoperatively. Lidocaine also lowered the incidence of postoperative pulmonary complications (23.1% vs 38.5%; P=0.007). Median plasma lidocaine concentrations were 1.5, 1.9, and 1.1 μg ml^-1 (inter-quartile ranges: 1.1-2.1, 1.4-2.6, and 0.8-1.6, respectively) after bolus injection, at the end of the surgery, and 24 h postoperatively.

CONCLUSIONS

Prolonged intravenous lidocaine infusion reduced the incidence of moderate-to-severe movement-evoked pain for 48 h after hepatectomy. However, the reduction in pain scores and opioid consumption by lidocaine was below the minimal clinically important difference.

CLINICAL TRIAL REGISTRATION

NCT04295330.

Factors associated with the decision to administer β-lactams via prolonged infusion in patients with sepsis: a prospective observational cohort study

OBJECTIVE

β-lactams are the most widely used antibiotics in sepsis. We aimed to explore the factors that drive physicians to choose prolonged infusion (PI) of β-lactams in septic patients.

METHODS

This prospective observational national cohort study was conducted in 40 ICUs at the teaching hospitals of 31 provinces in China between August 20, 2021 and September 20, 2021.

RESULTS

Of the 441 enrolled patients, 265 (60.09%) received PI therapy. Multivariate analysis showed that multidrug-resistant bacterial infection and septic shock were independent factors associated with PI. However, our data showed that the survival benefit of PI use was evident in subgroups with less severe sepsis, including those with lower Charlson comorbidity index values (<2), those without septic shock, and those with lower acute physiology and chronic health evaluation II scores (<15). Univariate and multivariate Cox regression indicated that PI was an independent protective factor of 28d mortality, even after adjusting the variables associated with disease severity.

CONCLUSIONS

PI for administering β-lactams was not a commonly applied strategy in sepsis and was more likely to be used in severely ill patients. However, PI had a survival benefit independent of disease severity.

Model-Informed Translation of In Vitro Effects of Short-, Prolonged- and Continuous-Infusion Meropenem against Pseudomonas aeruginosa to Clinical Settings

Pharmacokinetic-pharmacodynamic (PKPD) models have met increasing interest as tools to identify potential efficacious antibiotic dosing regimens in vitro and in vivo. We sought to investigate the impact of diversely shaped clinical pharmacokinetic profiles of meropenem on the growth/killing patterns of Pseudomonas aeruginosa (ARU552, MIC = 16 mg/L) over time using a semi-mechanistic PKPD model and a PK/PD index-based approach. Bacterial growth/killing were driven by the PK profiles of six patient populations (infected adults, burns, critically ill, neurosurgery, obese patients) given varied pathogen features (e.g., EC50, growth rate, inoculum), patient characteristics (e.g., creatinine clearance), and ten dosing regimens (including two dose levels and 0.5-h, 3-h and continuous-infusion regimens). Conclusions regarding the most favourable dosing regimen depended on the assessment of (i) the total bacterial load or fT>MIC (time that unbound concentrations exceed the minimum inhibitory concentration); (ii) the median or P0.95 profile of the population; and (iii) 8 h or 24 h time points. Continuous infusion plus loading dose as well as 3-h infusions (3-h infusions: e.g., for scenarios associated with low meropenem concentrations, P0.95 profiles, and MIC ≥ 16 mg/L) appeared superior to standard 0.5-h infusions at 24 h. The developed platform can serve to identify promising strategies of efficacious dosing for clinical trials.

Evaluation of the safety of cefepime prolonged infusions in pediatric patients with cystic fibrosis

OBJECTIVE

Pediatric cystic fibrosis (CF) patients possess unique pharmacokinetics and may benefit from prolonged beta-lactam infusions to optimize pharmacodynamics. This study compared adverse drug event (ADE) rates with cefepime prolonged (PI) and standard infusions (SI).

METHODS

This retrospective study included pediatric patients treated with cefepime for CF exacerbations between 2009 and 2019. One encounter per patient was analyzed with prioritization of SI encounters given sample size limitations. Baseline lab abnormalities, seizure disorders, and bleeding were exclusion criteria. The primary outcome was a composite safety endpoint (acute kidney injury [AKI], hepatotoxicity, hematologic toxicity, neurotoxicity, and hypersensitivity).

RESULTS

Of 188 patients, 135 received PI and 53 received SI. Baseline characteristics were similar between groups. More PI patients used CF transmembrane conductance regulator (CFTR) modulators (25% vs. 0%, p < 0.01) or had antibiotic allergies (62% vs. 38%, p = 0.02). Difference in rates of composite safety endpoint was not statistically significant between PI and SI (21 [15.6%] vs. 6 [11.3%] p = 0.46) nor was incidence of AKI (16 [11.8%] vs. 6 [11.3%], p = 0.92). Other ADEs were rarely observed. Length of stay (12.2 vs. 10.1 days, p = 0.06), change in discharge ppFEV1 from admission (13 vs. 12, p = 0.91) or from baseline (-4 vs. -6.5, p = 0.33), and time to next exacerbation (249.7 vs. 192.5 days, p = 0.93) were similar.

CONCLUSIONS

No difference in risk of ADEs including AKI was seen with cefepime PI in pediatric CF patients. Clinical outcomes were not significantly different between groups, but sample size may have limited comparison. PI cefepime may be considered in pediatric CF patients to optimize pharmacodynamics.

Prolonged Infusion of β-Lactams Decreases Mortality in Patients with Septic Shock: A Retrospective before-and-after Study

Septic shock substantially alters the pharmacokinetic properties of β-lactams with a subsequently high risk of insufficiently low serum concentrations and treatment failure. Considering their pharmacokinetic (PK)/pharmacodynamic (PD) index, prolonged infusions (PI) of β-lactams extend the time that the unbound fraction of the drug remains above the minimal inhibitory concentration MIC (ft _>MIC) and may improve patient survival. The present study is a monocentric, retrospective before-and-after analysis of septic shock patients treated with β-lactams. Patients of the years 2015–2017 received intermittent bolus application whereas patients of 2017–2020 received PI of β-lactams. The primary outcome was mortality at day 30 and 90 after diagnosis of septic shock. Mortality rates in the PI group were significantly lower on day 30 (PI: 41%, n = 119/290 vs. IB: 54.8%, n = 68/114; p = 0.0097) and day 90 (PI: 47.9%, n = 139/290 vs. IB: 62.9%, n = 78/124; p = 0.005). After propensity-score matching, 30- and 90-day mortality remained lower for the PI group (−10%, p = 0.14). PI was further associated with a reduction in the duration of invasive ventilation and a stronger decrease in SOFA scores within a 14 day-observation period. PI of β-lactams was associated with a significant reduction of mortality in patients with septic shock and may have beneficial effects on invasive ventilation and recovery from sepsis-related organ failure.

Assessment of Meropenem and Vaborbactam Room Temperature and Refrigerated Stability in Polyvinyl Chloride Bags and Elastomeric Devices

PURPOSE

Meropenem and vaborbactam is an intravenous beta-lactam/beta-lactamase inhibitor combination antibiotic active against multidrug resistant gram-negative bacteria. It may be a suitable treatment for inpatient and outpatient management of infections, and the intravenous admixture stability is therefore important for optimal utilization. The purpose of this study was to determine the stability of meropenem and vaborbactam in polyvinyl chloride (PVC) infusion bags and elastomeric pumps at room and refrigerated temperatures.

METHODS

Meropenem and vaborbactam vials were reconstituted according to manufacturer instructions and diluted in PVC infusion bags to final concentrations of 4, 8, and 16 mg/mL and in elastomeric pumps to 11.4 mg/mL (n = 5 replicates per concentration and per temperature). PVC bags and elastomeric pumps were stored at room temperature (~24 °C) or in the refrigerator (~4 °C) and sampled over 12 and 144 h, respectively. Stability was defined as the duration that meropenem and vaborbactam concentrations remained ≥90% of the original concentrations.

FINDINGS

All room temperature replicates across the tested concentrations retained meropenem and vaborbactam stability over 12 h and displayed concentration-dependent degradation. Refrigerated studies resulted in meropenem and vaborbactam stability at all tested concentrations up to 120 h.

IMPLICATIONS

Meropenem and vaborbactam in PVC bags (4, 8, and 16 mg/mL) and elastomeric pumps (11.4 mg/mL) were stable for 12 h at room temperature and 120 h when refrigerated. These stability data allow for enhanced flexibility in the preparation, storage, wastage, and administration of meropenem and vaborbactam in the hospital and outpatient setting.

Suitability of Amoxicillin-Clavulanic Acid for Administration via Prolonged Infusion

Rationale

Previously, we have been able to outpace bacterial mutation by replacing increasingly ineffective antibiotics with new agents. However, with the discovery of new antibiotics diminishing, optimising the administration of existing broad-spectrum antibiotics such as co-amoxiclav has become a necessity.

Methods

A stability indicating HPLC method was developed and validated in compliance with International Council for Harmonisation (ICH) guidelines. Stability of co-amoxiclav at clinical concentration was evaluated at three temperatures (4°C, ambient (23-25°C) and 37°C) in three diluents (water for injection (WFI), 0.9% w/v NaCl and Ringer's solution). To establish whether there were significant differences at the level of both diluent and temperature, results were analysed using analysis of covariance (ANCOVA) to assess differences between the attained slopes of regression.

Results

Data obtained indicated co-amoxiclav stability superior to that previously proposed making it suitable for extended infusion therapy. The degradation of amoxicillin appeared to follow a linear trend, with the rate of degradation elevated at higher temperatures, demonstrated by the magnitude of the regression slopes in these conditions. Analysis of regression slopes via ANCOVA demonstrated that diluent and temperature both significantly affected co-amoxiclav stability. Amoxicillin retained 90% of its initial concentration for 7.8 to 10 hrs when stored at 4°C, 5.9 to 8.8 hrs at ambient and 3.5 to 4.5 hrs when incubated at 37°C.

Conclusion

Co-amoxiclav is suitable for administration via prolonged infusion. Findings from this study aid in ameliorating current dosing regimens to optimise antibiotic efficacy. Other valuable applications conferred from these findings include the ability to pre-prepare solutions for use in bolus administration, minimising preparation time and workload.

Meropenem pharmacokinetics during relapsing peritonitis due to ESBL-producing Enterobacteriaciae in a liver transplant recipient

We report on an 8-year-old girl with Wilson disease who developed three episodes of peritonitis due to extended-spectrum beta-lactamase-producing Escherichia coli after liver transplantation. Massive ascites were thought to account for low meropenem concentrations with standard dosing. Extending the infusion achieved higher troughs, greater time above minimum inhibitory concentration.

The Pharmacodynamics of Prolonged Infusion β-Lactams for the Treatment of Pseudomonas aeruginosa Infections: A Systematic Review

PURPOSE

Pseudomonas aeruginosa is a commonly isolated nosocomial pathogen for which treatment options are often limited for multidrug-resistant isolates. In addition to newer available antimicrobial agents active against P. aeruginosa, strategies such as extended (eg, prolonged or continuous) infusion have been suggested to optimize the pharmacokinetic and pharmacodynamic profiles of β-lactams. Literature regarding clinical outcomes for extended infusion β-lactams has been controversial; however, this use seems most beneficial in patients with severe illness. Prolonged infusion of β-lactams (eg, 3- to 4-hour infusion) can enhance the pharmacodynamic target attainment via increasing the amount of time throughout the dosing interval to which the free drug concentration remains above the MIC (minimum inhibitory concentration) of the organism (fT > MIC). This systematic review summarizes current literature related to the probability of target attainment (PTA) of various antipseudomonal β-lactam regimens administered as prolonged infusions in an effort to provide guidance in selecting optimal dosing regimens and infusion times for the treatment of P. aeruginosa infections.

METHODS

A literature search for all pertinent studies was performed by using the PubMed database (with no year limit) through March 31, 2019.

FINDINGS

Thirty-nine studies were included. Although many standard antipseudomonal β-lactam intermittent infusion regimens can provide adequate PTA against most susceptible isolates, prolonged infusion may enhance percent fT > MIC for organisms with higher MICs (eg, nonsusceptible) or patients with altered pharmacokinetic profiles (eg, obese, critically ill, those with febrile neutropenia).

IMPLICATIONS

Prolonged infusion β-lactam regimens can enhance PTA against nonsusceptible P. aeruginosa isolates and may provide a potential therapeutic option for multidrug-resistant infections. Before implementing prolonged infusion antipseudomonal β-lactams, institutions should consider the half-life of the antibiotic, local incidence of P. aeruginosa infections, antibiotic MIC distributions or MICs isolated from individual patients, individual patient characteristics that may alter pharmacokinetic variables, and PTA (eg, critically ill), as well as implementation challenges.

Prolonged low-dose infusion for gemcitabine: a systematic review

Background

The present standard dose of gemcitabine (Gem), a pyrimidine antimetabolite, is 1,000-1,250 mg/m², and the infusion time is 30 min. However, pharmacological studies have demonstrated that Gem with prolonged infusion could attain a better accumulation rate of Gem triphosphate (active metabolites of Gem), indicating that Gem with prolonged infusion is superior to 30-min infusion. Thus, this systematic review aims to provide some references for Gem administered as a prolonged infusion.

Methods

We searched electronic databases, including PubMed, EMBASE, Cochrane Library, and CNKI, for trials. Keywords were "Gem," "prolonged infusion," and "low-dose." In addition, we used the Cochrane Handbook V5.1.0 and methodological index for non-randomized studies to evaluate the quality of randomized controlled trials (RCTs) and non-RCTs, respectively. Furthermore, Cochrane Collaboration guidelines and the PRISMA statement were adopted.

Results

We systematically reviewed 19 studies (5 RCTs and 14 non-RCTs). All studies assessed the efficacy and safety of Gem administered as a prolonged low-dose infusion (P-LDI) and reported that Gem administered as P-LDI was effective and well tolerated.

Conclusion

Gem administered as P-LDI is effective, safe, and economical, especially suited for patients with poor performance status or without good economic condition.

Population Pharmacokinetic Analysis of Meropenem After Intravenous Infusion in Korean Patients With Acute Infections

PURPOSE

The aim of this study was to investigate the population pharmacokinetic (PK) profile of meropenem in Korean patients with acute infections.

METHODS

The study included 37 patients with a creatinine clearance ≤50 or >50 mL/min who received a 500- or 1000-mg dose of meropenem, respectively, infused intravenously over 1 hour every 8 hours. Blood samples were collected before and at 1, 1.5, and 5 hours after the start of the fourth infusion. The population PK analysis was conducted by using nonlinear mixed effect modeling software (NONMEM). Monte-Carlo simulations were performed to identify optimal dosing regimens.

FINDINGS

Thirty-seven subjects completed the study. Meropenem PK variables were well described by using a one-compartment model. The typical values (relative SE) for weight-normalized clearance (CL) and V_d were 0.266 L/h/kg (12.29%) and 0.489 L/kg (11.01%), respectively. Meropenem CL was significantly influenced by the serum creatinine level, which explained 11% of the interindividual CK variability. The proposed equation to estimate meropenem CL in Korean patients was as follows: CL (L/h) = 0.266 × weight × [serum creatinine/0.74]^-1.017_. The simulation results indicate that the current meropenem dosing regimen may be suboptimal in patients infected with normal or augmented renal function.

IMPLICATIONS

Prolonged infusions of meropenem over at least 2 hours should be considered, especially in patients with augmented renal function and those infected with pathogens for which the minimum inhibitory meropenem concentration is >1 μg/mL. Our results suggest an individualized meropenem dosing regimen for patients with abnormal renal function and those infected with pathogens with decreased in vitro susceptibility.

Therapeutic Drug Monitoring of Prolonged Infusion Aztreonam for Multi-Drug Resistant Pseudomonas aeruginosa: A Case Report

Aztreonam, a broad-spectrum monobactam, is typically reserved for multidrug resistant (MDR) infections. Pharmacokinetic (PK) data to guide dosing in children, however, are limited to healthy volunteers or nonintensive care unit (ICU) patients. Impaired antibiotic delivery into tissue remains a major concern and may explain the high morbidity and mortality associated with MDR infections. Therefore, evaluating the PK changes in pediatric ICU patients is necessary to elucidate the most appropriate antimicrobial regimen. We describe the PK of prolonged infusion aztreonam in a patient with MDR Pseudomonas aeruginosa empyema. The 16-year-old tetraplegic male with a cervical spinal cord injury, chronic respiratory failure, and tracheostomy was admitted with a 2-day history of fever and hypoxemia. Chest x-ray revealed a left lower lobe infiltrate. On hospital day 2, computed tomography scan noted a massive collapse of the left lung with bronchiectasis and hepatization with a pneumatocele. He underwent bronchoscopy on days 2, 6, and 10 and the cultures subsequently grew P aeruginosa only sensitive to aztreonam (minimum inhibitory concentration [MIC] of 2-6 mg/L). A regimen of aztreonam 2 grams intravenously (IV) every 6 hours (each dose infused over 4 hours) and polymyxin B 1,000,000 units IV every 12 hours (each dose infused over 30 minutes) was initiated on day 3. On day 8, the aztreonam serum plateau concentration was 71 mg/L. Repeat respiratory and bronchoscopy cultures from days 19 to 37 remained negative. Aztreonam clearance was 2.3 mL/kg/min, which was significantly increased when compared with the 1.3 mL/kg/min suggested in the prescribing information based on adult data. A prolonged infusion of 2 grams of aztreonam every 6 hours (each dose infused over 4 hours) successfully attained 100% of the target serum and lung concentrations above the MIC for at least 40% of the dosing interval, and was associated with successful treatment of MDR P aeruginosa empyema.

Hospital Length of Stay Among Patients Receiving Intermittent Versus Prolonged Piperacillin/Tazobactam Infusion in the Intensive Care Units

OBJECTIVES

We sought to evaluate clinical outcomes of intensive care unit (ICU) patients following a hospital-wide initiative of prolonged piperacillin/tazobactam (PIP/TAZ) infusion.

METHODS

Retrospective observational study of patients >18 years old who was hospitalized in the ICU receiving PIP/TAZ for >72 hours during the preimplementation (June 1, 2010 to May 31, 2011) and postimplementation (July 7, 2011 to June 30, 2014) periods.

RESULTS

There were 124 and 429 patients who met inclusion criteria with average age of 54.3 and 56.9 years, and average duration of PIP/TAZ therapy was 6.1 ± 2.8 days and 5.9 ± 3.4 days in the pre- and postimplementation period, respectively. Intensive care unit and hospital length of stay (LOS) following initiation of PIP/TAZ were 8.0 ± 8.4 days versus 6.4 ± 6.8 days and 26.3 ± 22.8 days versus 20.4 ± 16.1 days among patients in the pre- and postimplementation periods, respectively. Compared to patients who received intermittent PIP/TAZ infusion, the adjusted difference in ICU and hospital LOS was 0.6 ± 0.8 days (95% confidence interval [CI]: -0.9 to 2.1 days) and 5.6 ± 2.1 days (95% CI: 1.4 - 9.7 days) shorter among patients who received prolonged PIP/TAZ infusion. At hospital discharge, 19 (15.3%) intermittent infusion and 74 (17.2%) prolonged infusion recipients had died. In comparison to intermittent infusion recipients, the adjusted odds ratio for mortality was 1.17 (95% CI: 0.65-2.1) with prolonged infusion.

CONCLUSION

Our study demonstrated a reduction in hospital LOS with prolonged PIP/TAZ infusion among critically ill patients. Randomized trials are needed to further validate these findings.

Population Pharmacokinetic Analysis of Doripenem after Intravenous Infusion in Korean Patients with Acute Infections

We investigated the population pharmacokinetics (PK) of doripenem in Korean patients with acute infections and determined an appropriate dosing regimen using a Monte Carlo simulation for predicting pharmacodynamics (PD). Patients (n = 37) with a creatinine clearance (CL_CR) of 20 to 50 ml/min or >50 ml/min who received a 250-mg or 500-mg dose of doripenem over the course of 1 h every 8 h, respectively, were included in this study. Blood samples were taken predosing and 0 h, 0.5 h, and 4 to 6 h after the fourth infusion. A nonlinear mixed-effect modeling tool was used for the PK analysis and pharmacodynamic simulation; doripenem PK were well described by a one-compartment model. The population mean values of the body weight (WT)-normalized clearance (CL/WT) and the body weight-normalized volume of distribution (V/WT) were 0.109 liter/h/kg of body weight (relative standard error, 9.197%) and 0.280 liter/kg (relative standard error, 9.56%), respectively. Doripenem CL was significantly influenced by CL_CR The proposed equation to estimate doripenem CL in Korean patients was CL/WT = 0.109 × WT × (CL_CR/57)^0.688, where CL/WT is in liters per hour per kilogram. CL in Korean patients was expected to be lower than that in Caucasian patients, regardless of renal function. The Monte Carlo simulation showed that 90% attainment of target PK/PD magnitudes could be achieved with the usual dosing regimens when the MIC was ≤1 mg/liter. However, prolonged infusions (4 h) should be considered, especially when patients have augmented renal function and for patients infected with pathogens with a high MIC. Our results provide an individualized doripenem dosing regimen for patients with various renal functions and for patients infected with bacteria with decreased susceptibility.

Comparison of Short Versus Prolonged Infusion of Standard Dose of Meropenem Against Carbapenemase-Producing Klebsiella pneumoniae Isolates in Different Patient Groups: A Pharmacokinetic-Pharmacodynamic Approach

Dose optimization is required to increase carbapenem's efficacy against carbapenemase-producing isolates. Four clinical Klebsiella pneumoniae isolates were used: one susceptible to meropenem with minimum inhibitory concentration (MIC) 0.031 mg/L and 3 verona integron-borne metallo bete-lactamase-1-producing isolates with MICs 8, 16, and 128 mg/L. The human pharmacokinetics of short (0.5-h) and prolonged (3-h) infusion regimens of 1 g meropenem every 8 h were simulated in an in vitro pharmacokinetic-pharmacodynamic model. Time-kill curves were constructed for each isolate and dosing regimen, and the %T > MIC associated with maximal bactericidal activity was estimated. The percentage of pharmacodynamic target attainment for isolates with different MICs was calculated for 350 ICU, surgical, and internal medicine patients. The isolates with MIC ≤8 mg/L were killed with both dosing regimens. The %T > MIC corresponding to maximal bactericidal activity was ∼40%. The percentages of target attainment were >90%, 61%-83%, 23%-33%, and <3% with the short infusion regimen and >90%, 98%-99%, 55%-79%, and <5% with the prolonged infusion regimen for isolates with MIC ≤2, 4, 8, and ≥16 mg/L, respectively. The lowest target attainment rates were observed for the ICU patients and the highest for internal medicine patients. The prolonged infusion regimen was more effective than the short infusion regimen against isolates with MIC 4-8 mg/L.

Pharmacokinetics of an extended 4-hour infusion of piperacillin-tazobactam in critically ill patients undergoing continuous renal replacement therapy

STUDY OBJECTIVE

To evaluate the pharmacokinetic and pharmacodynamic profiles of piperacillin-tazobactam administered as a 4-hour infusion in critically ill patients undergoing continuous renal replacement therapy (CRRT).

DESIGN

Prospective, observational, pharmacokinetic study.

SETTING

Intensive care unit of a tertiary care hospital in Montréal, Canada.

PATIENTS

Twenty critically ill adults who were undergoing continuous venovenous hemodiafiltration and receiving a 4-hour infusion of piperacillin 4 g-tazobactam 0.5 g every 8 hours for a documented or suspected infection.

INTERVENTION

Blood samples were collected every hour over an 8-hour dosing interval. Prefilter and postfilter blood samples, and effluent and urine samples were also collected.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the proportion of patients who achieved an unbound piperacillin plasma concentration above a target minimum inhibitory concentration (MIC) of 64 mg/L (MIC that inhibits 90% of isolates for Pseudomonas aeruginosa) for at least 50% of the dosing interval; 18 (90%) of the 20 patients achieved this outcome. In all patients, the free piperacillin concentrations were above the Pseudomonas aeruginosa breakpoint of 16 mg/L for the entire time interval. Regarding piperacillin pharmacokinetic parameters, the median (interquartile range) minimum unbound plasma concentration was 65.15 mg/L (51.30-89.30), maximum unbound plasma concentration was 141.3 mg/L (116.75-173.90), sieving coefficient was 0.809 (0.738-0.938), total clearance was 65.82 ml/minute (53.79-102.87), and renal clearance was 0.16 ml/minute (0.05-3.04). The median CRRT dose was 32.0 ml/kg/h (25.0-39.8).

CONCLUSIONS

Administration of a 4-hour infusion of piperacillin-tazobactam was associated with a favorable pharmacodynamic profile in patients undergoing CRRT. Concentrations associated with maximal activity were attained in our patients.

Importance of dose intensity in treatment of advanced non-small cell lung cancer in the elderly

Maintaining appropriate dose intensity is important not only in the curative setting but also in treatment with palliative intent. We evaluated the outcome of advanced non small cell lung cancer treated with doublet platinum based chemotherapy. Outcome was compared between patients treated by medical oncologists at a tertiary cancer center and those treated by non medical oncologists in the community. The dose intensity, overall response rate and overall survival was significantly better when patients were treated by trained qualified and experienced medical oncologists. Hence, even in the palliative setting, cancer directed systemic therapy will yield maximum benefit for the patients when treated by medical oncologists.