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A recent systematic review and meta-analysis of randomized controlled trials (RCTs) evaluated the efficacy and safety of prolonged versus intermittent β-lactam infusion in adult sepsis patients. The findings revealed a significant decrease in all-cause mortality and marked clinical success in the prolonged infusion group. Unfortunately, however, the manuscript lacked data and discussion for the specific regimens of prolonged β-lactam infusion defined in the included 15 RCT studies, which are herein additionally provided. Excluding one RCT, all protocols adopted a continuous infusion for the prolonged treatment. Except for three RCTs, dosages and timings of bolus injection were clearly defined. The total daily antibiotic dose for the continuous therapy was equivalent to those recommended for intermittent therapy. We believe this supplementary data aids clinicians in providing prolonged β-lactam infusions, contributing to enhanced treatment outcomes for patients suffering from severe sepsis or septic shock. [ABSTRACT FROM AUTHOR]

Background: Acyclovir represents the first-line prophylaxis and therapy for herpes virus infections. However, its pharmacokinetics in children exposes them to the risk of ineffective or toxic concentrations. The study was aimed at investigating the population pharmacokinetics (POP/PK) of intravenous (IV) acyclovir in oncologic children. Methods: Patients (age, 8.6 ± 5.0 years, 73 males and 47 females) received IV acyclovir for prophylaxis (n = 94) and therapy (n = 26) under a therapeutic drug monitoring (i.e., minimum and maximal plasma concentrations, >0.5 and <25 mg/L, respectively). Plasma concentrations were fitted by nonlinear mixed effect modeling and a simulation of dosing regimens was performed. Findings were stratified according to an estimated glomerular filtration rate (eGFR) threshold of 250 ml/min/1.73 m2. Results: The final 1-compartment POP/PK model showed that eGFR had a significant effect on drug clearance, while allometric body weight influenced both clearance and volume of distribution. The population clearance (14.0 ± 5.5 L/h) was consistent across occasions. Simulation of standard 1-h IV infusion showed that a 10-mg/kg dose every 6 h achieved target concentrations in children with normal eGFR (i.e., ≤250 ml/min/1.73 m2). Increased eGFR values required higher doses that led to an augmented risk of toxic peak concentrations. On the contrary, simulated prolonged (i.e., 2 and 3-h) or continuous IV infusions at lower doses increased the probability of target attainment while reducing the risk of toxicities. Conclusion: Due to the variable pharmacokinetics of acyclovir, standard dosing regimens may not be effective in some patients. Prospective trials should confirm the therapeutic advantage of prolonged and continuous IV infusions [ABSTRACT FROM AUTHOR]

Abstract 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.

Fosfomycin (FOS) administered intravenously has been recently rediscovered for the treatment of systemic infections due to multidrug-resistant bacteria. Its pharmacokinetic properties suggest a time-dependent dosing schedule with more clinical benefits from prolonged (PI) or continuous infusion (CI) than from intermittent infusion. We revised literature concerning PI and CI FOS to identify the best dosing regimen based on current evidence. We performed a MEDLINE/PubMed search. Ninety-one studies and their pertinent references were screened. Seventeen studies were included in the present review. The activity of FOS against Gram-negative and Gram-positive bacteria was evaluated in fourteen and five studies, respectively. Six studies evaluated FOS activity in combination with another antibiotic. Daily dosing of 12, 16, 18 or 24 g, administered with different schedules, were investigated. These regimens resulted active against the tested isolates in most cases. Emergence of resistant isolates has been shown to be preventable through the coadministration of another active antibiotic. FOS is a promising option to treat systemic infections caused by multidrug-resistant bacteria. Coadministration with another active molecule is required to prevent the emergence of resistant bacterial strains. The results of our review suggest that a therapeutic regimen including a loading dose of FOS 8 g followed by a daily dose of 16 g or 24 g CI could be the best therapeutic approach for patients with normal renal function. The dosing regimens in patients with renal insufficiency and CI or PI superiority compared with intermittent infusion in clinical settings should be further investigated. [ABSTRACT FROM AUTHOR]

Objective: We previously investigated the pharmacokinetic and pharmacodynamic (PK/PD) parameters of routine linezolid infusions (1 h) in patients with external ventricular drains (EVD). The aim of the study was to determine whether extended linezolid infusions (200 mg/h for 3 h) were more efficacious than short linezolid infusions (600 mg/h for 1 h). Methods: We collected cerebrospinal fluid (CSF) and plasma samples from 10 patients who received linezolid infusions after cerebral hemorrhage surgery with EVDs. Linezolid concentrations were measured by high-performance liquid chromatography (HPLC). A Monte Carlo simulation was used to measure the probability of target attainments (PTA) and the PK/PD indexes at four minimum inhibitory concentrations (MIC). Results: When the same dose (600 mg) was given as an extended infusion (3 h), linezolid reached its maximum concentrations in the plasma and CSF at 3.00 h and 4.40 h, respectively. The mean penetration of linezolid in CSF was 41.31%. Using the parameter of AUC0–24 h/MIC ≥ 100, the plasma PTA provided good coverage at > 90% when MIC was ≤ 1 μg/mL, while the values were 0 in CSF. Using the parameter %T (time) > MIC ≥ 85%, the PTA in both the plasma and CSF provided good coverage when MIC ≤ 2 μg/mL. Compared with routine infusions, prolonged infusion times (3 h) showed increased PTA of linezolid. Conclusions: Prolonged infusion times increased the concentration of linezolid in the plasma, leading to improved therapeutic outcomes. However, this improvement did not exist in CSF. Lastly, the PK/PD indicator AUC/MIC ≥ 100 may be used to achieve improved outcomes in patients with critical infections. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Pharmacodynamic concepts should be applied to optimize antibiotic dosing regimens, particularly in the face of some multidrug resistant bacterial infections. Although the pharmacodynamics of most antibiotic classes used in the hospital setting are well described, guidance on how to select regimens and implement them into an antimicrobial stewardship program in one's institution are more limited. The role of the antibiotic MIC is paramount in understanding which regimens might benefit from implementation as a protocol or use in individual patients. This review article outlines the pharmacodynamics of aminoglycosides, beta-lactams, fluoroquinolones, tigecycline, vancomycin, and polymyxins with the goal of providing a basis for strategy to select an optimized antibiotic regimen in your hospital setting.

Purpose: This study aims to determine if continuous infusion (CI) is associated with better clinical and pharmacokinetic/pharmacodynamic (PK/PD) outcomes compared to intermittent bolus (IB) dosing in critically ill patients with severe sepsis.Methods: This was a two-centre randomised controlled trial of CI versus IB dosing of beta-lactam antibiotics, which enrolled critically ill participants with severe sepsis who were not on renal replacement therapy (RRT). The primary outcome was clinical cure at 14 days after antibiotic cessation. Secondary outcomes were PK/PD target attainment, ICU-free days and ventilator-free days at day 28 post-randomisation, 14- and 30-day survival, and time to white cell count normalisation.Results: A total of 140 participants were enrolled with 70 participants each allocated to CI and IB dosing. CI participants had higher clinical cure rates (56 versus 34 %, p = 0.011) and higher median ventilator-free days (22 versus 14 days, p < 0.043) than IB participants. PK/PD target attainment rates were higher in the CI arm at 100 % fT >MIC than the IB arm on day 1 (97 versus 70 %, p < 0.001) and day 3 (97 versus 68 %, p < 0.001) post-randomisation. There was no difference in 14-day or 30-day survival between the treatment arms.Conclusions: In critically ill patients with severe sepsis not receiving RRT, CI demonstrated higher clinical cure rates and had better PK/PD target attainment compared to IB dosing of beta-lactam antibiotics. Continuous beta-lactam infusion may be mostly advantageous for critically ill patients with high levels of illness severity and not receiving RRT. Malaysian National Medical Research Register ID: NMRR-12-1013-14017. [ABSTRACT FROM AUTHOR]

Background Patients with cystic fibrosis (CF) exhibit increased clearance of beta-lactams. The purpose of this study was to predict the probability of beta-lactam target attainment (PTA) against Pseudomonas aeruginosa in adult CF patients based on local microbiological data. Methods CF-specific pharmacokinetic parameters were obtained from published data for aztreonam, cefepime, ceftazidime, meropenem and piperacillin–tazobactam. Pharmacodynamic modeling was used to determine the PTA for bolus, prolonged infusion, and continuous infusion regimens. Results Prolonged infusion of meropenem 2 g every 8 h performed the best among all regimens tested, with a PTA of 83%. The PTA was increased with both prolonged and continuous infusion; however, no regimen reached the target PTA of > 90% against P. aeruginosa in CF patients at our institution. Conclusions Prolonged and continuous infusion provided higher PTA than bolus for all regimens. Further investigation of novel regimens in CF patients is needed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In critically ill patients, pathophysiological changes alter the pharmacokinetics of antibiotics. Imipenem exhibits primarily time-dependent killing. Its administration by prolonged infusion may increase the time for which its plasma concentration exceeds the minimum inhibitory concentrations (MICs) of suspected pathogens. The objectives of this study were to compare the pharmacokinetic parameters of imipenem administered by standard short infusion (1 g imipenem/1 g cilastatin over 30 min three times daily) and by extended infusion with a reduced total dose (0.5 g imipenem/0.5 g cilastatin over 3 h four times daily) and to compare the target pharmacokinetic/pharmacodynamic indices, namely percentage of the dosing interval for which the free plasma concentration of imipenem exceeds the MIC and 4× MIC (% f T >MIC and % f T >4×MIC ) of 0.5, 1, 2 and 4 mg/L, for these two regimens in critically ill adult patients with nosocomial pneumonia on Day 2 of empirical antibiotic therapy. The study included 22 patients. Whilst no significant differences were found between both groups for % f T >MIC , % f T >4×MIC was 87.4 ± 12.19%, 68.6 ± 15.08%, 47.31 ± 6.64% and 27.81 ± 9.52% of the 8-h interval in the short infusion group for MICs of 0.5, 1, 2 and 4 mg/L, respectively, and 85.15 ± 17.57%, 53.14 ± 27.27%, 13.55 ± 24.47% and 0 ± 0% of the 6-h interval for the extended infusion group. In conclusion, administration of 0.5 g of imipenem by a 3-h infusion every 6 h does not provide sufficient drug concentrations to treat infections caused by pathogens with a MIC of ≥2 mg/L. [ABSTRACT FROM AUTHOR]

Abstract: The study objective was to evaluate steady-state pharmacokinetics and pharmacodynamics of piperacillin and tazobactam administered by prolonged infusion in obese patients. Fourteen hospitalised patients weighing >120kg received piperacillin/tazobactam 4.5g every 8h (q8h) or 6.75g q8h infused over 4h. Blood samples were collected at steady-state and drug concentrations were determined. Pharmacokinetic parameters were estimated and 5000-patient Monte Carlo simulations were performed for four prolonged-infusion dosing regimens. The probability of target attainment (PTA) for ≥50% fT >MIC was calculated for piperacillin at various MICs, and the PTA for fAUC0–24 ≥96mgh/L was calculated for tazobactam. Mean±S.D. patient demographics were: age 49±10 years; weight 161±29kg; and body mass index 52.3±10.8kg/m2. For piperacillin and tazobactam, respectively, the mean±S.D. elimination rate was 0.440±0.177h−1 and 0.320±0.145h−1, volume of distribution was 33.4±14.0L (0.21±0.07L/kg) and 37.5±15.3L (0.23±0.08L/kg), and systemic clearance was 13.7±5.2L/h and 11.1±4.2L/h. For piperacillin, the PTA was ≥91% for doses ≥4.5g q8h at MICs≤16μg/mL. For tazobactam, the PTA was 57%, 84% and 94% for doses of 4.5, 6.75 and 9.0g q8h, respectively. The pharmacokinetics of piperacillin and tazobactam are altered in obese patients. To ensure adequate tazobactam concentrations for β-lactamase inhibition, it may be prudent to employ larger initial doses for empirical therapy in obese patients. [Copyright &y& Elsevier]

The pharmacokinetics of doripenem and doripenem-M-1 (inactive metabolite) were evaluated in an open-label, 2-period, single-sequence study in which single 1-g and 2-g doses of doripenem were administered intravenously over 4 hours to adult patients with cystic fibrosis (CF). The systemic exposure to doripenem and doripenem-M-1, as measured by observed apparent maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC), increased approximately proportionally to the increase in dose. Other pharmacokinetic parameters of doripenem and doripenem-M-1, including clearance, volume of distribution, and elimination half-life, were similar for the 1-g and 2-g doses. The results from this study were also compared with those from a previous study in adult healthy volunteers (HVs) without CF, from a previously conducted pharmacokinetic study, who received single doses of 500 mg and 1 g doripenem administered over 4 hours. The pharmacokinetics of doripenem in adult patients with CF are similar to those from adult HVs, noting some differences in the disposition when comparing body mass index–adjusted pharmacokinetic parameters. [ABSTRACT FROM PUBLISHER]

Purpose: To develop a meropenem population pharmacokinetic model in critically ill patients with particular focus on optimizing dosing regimens based on renal function. Methods: Population pharmacokinetic analysis was performed with creatinine clearance (CrCl) and adjusted body weight to predict parameter estimates. Initial modeling was performed on 21 patients (55 samples). Validation was conducted with 12 samples from 5 randomly selected patients excluded from the original model. A 5,000-patient Monte Carlo simulation was used to ascertain optimal dosing regimens for three CrCl ranges. Results: Mean ± SD age, APACHE, and CrCl were 59.2 ± 16.8 years, 13.6 ± 7, and 78.3 ± 33.7 mL/min. Meropenem doses ranged from 0.5 g every 8 h (q8h)-2 g q8h as 0.5-3 h infusions. Median estimates for volume of the central compartment, K, and K were 0.24 L/kg, 0.49 h, and 0.65 h, respectively. K was described by the equation: K = 0.3922 + 0.0025 × CrCl. Model bias and precision were −1.9 and 8.1 mg/L. R, bias, and precision for the validation were 93%, 1.1, and 2.6 mg/L. At minimum inhibitory concentrations (MICs) up to 8 mg/L, the probability of achieving 40% fT > MIC was 96, 90, and 61% for 3 h infusions of 2 g q8h, 1 g q8h, and 1 g q12h in patients with CrCl ≥50, 30-49, and 10-29, respectively. Target attainment was 75, 65, and 44% for these same dosing regimens as 0.5 h infusions. Conclusions: This pharmacokinetic model is capable of accurately estimating meropenem concentrations in critically ill patients over a range of CrCl values. Compared with 0.5 h infusions, regimens employing prolonged infusions improved target attainment across all CrCl ranges. [ABSTRACT FROM AUTHOR]

Although some studies have suggested that gemcitabine delivered as a fixed dose rate (FDR) infusion of 10 mg/m2/min could be more effective than when administered as the standard 30-min infusion, the available pharmacokinetic data are still too limited to draw definitive conclusions. This study is aimed to investigate the plasmatic and intracellular pharmacokinetics of gemcitabine given as FDR at doses of 600 and 1,200 mg/m2 in combination with 75 mg/m2 of cisplatin in advanced non-small-cell lung cancer (NSCLC) patients. The patients were divided into two groups receiving different initial doses of the drug: 4 patients received 600 mg/m2 gemcitabine 60-min i.v. infusion and 4 patients 1,200 mg/m2 gemcitabine 120-min i.v. infusion both as a FDR of 10 mg/m2/min on days 1 and 8 of a 21-day cycle (at first cycle). At the second cycle, all patients were treated with gemcitabine at 1,200 mg/m2 120-min i.v. infusion (FDR of 10 mg/m2/min) on days 1 and 8 of a 21-day cycle. At each cycle, gemcitabine was administered alone on day one, and in combination with 75 mg/m2 of cisplatin on day 8. Plasmatic and intracellular pharmacokinetic analyses were performed on blood samples collected at defined time points before, during and after gemcitabine infusion. The plasmatic pharmacokinetic parameters were clearly different when the patients received a higher gemcitabine dose in the second cycle compared to the lower dose of the first course; in the same time, the intracellular drug levels were not modified. Comparing the pharmacokinetic parameters of different patients treated at different dose levels, the results appeared to be quite similar. A substantially higher accumulation of metabolites in peripheral blood mononuclear cells was observed when the longer infusion time was employed, suggesting a pharmacological advantage for this treatment schedule. [ABSTRACT FROM AUTHOR]

Prolonged infusion (PI) of β-lactam antibiotics is increasingly used in order to optimise antibiotic exposure in critically ill patients. Physicians are often not aware of a number of subtleties that may jeopardise the treatment. In this clinically based paper, we stress pragmatic issues, such as the importance of a loading dose before PI, and discuss a number of important practicalities that are mandatory to benefit from the pharmacokinetic advantages of prolonged β-lactam antibiotic administration. [ABSTRACT FROM AUTHOR]