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Journal of Antimicrobial Chemotherapy, 1996
The most important pharmacodynamic parameter for /?-lactam antibiotics has been shown to be the time above the MIC, which is used as an argument to administer /?-lactam antibiotics by continuous infusion. Studies in vitro and in laboratory animals comparing efficacy of continuous and intermittent infusion of /J-lactam antibiotics generally show continuous infusion to be more efficacious. While comparative trials in humans are scarce and a significant difference was only found in subgroup analysis in one study, several case-reports support the use of continuous infusion. Arguments in favour and against continuous infusion are discussed. Although dose-ranging studies have not yet been performed in humans, the results from in-vitro and in-vivo experiments indicate that 4 x MIC for the infecting bacterium would be the target concentration. Pharmacokinetic studies which have been performed in humans during continuous infusion show that serum concentrations can be predicted from total clearance or, using population pharmacokinetic modelling, the elimination rate constant as obtained during intermittent infusion. A nomogram is presented which allows calculation of the daily dose to obtain the target steady state blood concentrations suggested by the susceptibility of the infecting bacterium, usually 4 x MIC. For bacteria with a low MIC, the daily dose may be substantially lower than that used in conventional dosing regimens, while in infections which are difficult to treat as a result of more resistant bacteria, continuous infusion may be more effective than an equivalent bolus dose.
Continuous Infusion of Antibiotics in Critically Ill Patients
Current Clinical Pharmacology, 2013
The alarming global rise of antimicrobial resistance combined with the lack of new antimicrobial agents has led to a renewed interest in optimization of our current antibiotics. Continuous infusion (CI) of time-dependent antibiotics has certain theoretical advantages toward efficacy based on pharmacokinetic/pharmacodynamic principles. We reviewed the available clinical studies concerning continuous infusion of beta-lactam antibiotics and vancomycin in critically ill patients. We conclude that CI of beta-lactam antibiotics is not necessarily more advantageous for all patients. Continuous infusion is only likely to have clinical benefits in subpopulations of patients where intermittent infusion is unable to achieve an adequate time above the minimal inhibitory concentration (T > MIC). For example, in patients with infections caused by organisms with elevated MICs, patients with altered pharmacokinetics (such as the critically ill) and possibly also immunocompromised patients. For vancomycin CI can be chosen, not always for better clinical efficacy, but because it is practical, cheaper, associated with less AUC 24h (area under the curve >24 h)-variability, and easier to monitor.
2008
Purpose of review Increasing interest is being directed toward possible benefits associated with continuous infusion of time-dependent antibiotics such as b-lactams and vancomycin to critically ill patients. The background, emerging evidence and practical considerations associated with continuous infusions are discussed. Recent findings One large retrospective cohort study has found clinical outcome benefits of administering a b-lactam antibiotic by extended infusion compared with bolus administration. This complements a smaller randomized controlled trial comparing continuous infusion and intermittent bolus administration. For vancomycin, clinical outcome benefits have only been shown in a ventilator-associated pneumonia cohort of critically ill patients. No clinical outcome studies have been conducted for other timedependent antibiotics. Summary Continuous infusion of vancomycin and b-lactam antibiotics enables faster and more consistent attainment of therapeutic levels compared with intermittent bolus dosing. Although the clinical benefits have not been conclusively shown at this time, compelling pharmacokinetic/pharmacodynamic support for continuous infusion nevertheless exists. Given that critically ill patients may develop very large volumes of distribution as well as supranormal drug clearances, individualized therapy through the use of therapeutic drug monitoring is required. A definitive determination of the relative clinical efficacy of intermittent bolus and continuous administration of b-lactams or vancomycin will only be achieved after a large-scale multicenter randomized controlled trial has been performed.
2014
ORIGINAL range) age was 60 (47-73) years, APACHE II score was 18 (13-24). In the hypothetical situation of empirical dosing, antibiotic concentrations remained below the MIC during 50 % and 100 % of the dosing interval in 66 (19.2 %) and 142 (41.4 %) patients respectively. The use of intermittent infusion was significantly associated with increased risk of nonattainment for both targets; creatinine clearance was independently associated with not reaching the 100 % f T [MIC target. Conclusions: This study found that-in empirical dosing and considering a worst-case scenario-19 % and 41 % of the patients would not achieve antibiotic concentrations above the MIC during 50 % and 100 % of the dosing interval. The use of intermittent infusion (compared to extended and continuous infusion) was the main determinant of non-attainment for both targets; increasing creatinine clearance was also associated with not attaining concentrations above the MIC for the whole dosing interval. In the light of this study from 68 ICUs across ten countries, we believe current empiric dosing recommendations for ICU patients are inadequate to effectively cover a broad range of susceptible organisms and need to be reconsidered.
2012
The alarming global rise of antimicrobial resistance combined with the lack of new antimicrobial agents has led to a renewed interest in optimization of our current antibiotics. Continuous infusion (CI) of time-dependent antibiotics has certain theoretical advantages toward efficacy based on pharmacokinetic/pharmacodynamic principles. We reviewed the available clinical studies concerning continuous infusion of beta-lactam antibiotics and vancomycin in critically ill patients. We conclude that CI of beta-lactam antibiotics is not necessarily more advantageous for all patients. Continuous infusion is only likely to have clinical benefits in subpopulations of patients where intermittent infusion is unable to achieve an adequate time above the minimal inhibitory concentration (T > MIC). For example, in patients with infections caused by organisms with elevated MICs, patients with altered pharmacokinetics (such as the critically ill) and possibly also immunocompromised patients. For vancomycin CI can be chosen, not always for better clinical efficacy, but because it is practical, cheaper, associated with less AUC 24h (area under the curve >24 h)-variability, and easier to monitor.
Continuous infusion of β-lactam antibiotics in severe infections: a review of its role
International Journal of Antimicrobial Agents, 2007
Background. Beta-lactam antibiotics are a commonly used treatment for severe sepsis, with intermittent bolus dosing standard therapy, despite a strong theoretical rationale for continuous administration. The aim of this trial was to determine the clinical and pharmacokinetic differences between continuous and intermittent dosing in patients with severe sepsis.
Pulse Dosing Versus Continuous Infusion of Antibiotics
Clinical Pharmacokinetics, 1988
The issue of whether it is better to administer antibiotics as an intermittent bolus dose or a continuous intravenous infusion has been debated for several decades. This paper reviews the extensive literature on the topic. considering both the pharmacokinetic and pharmacodynamic aspects of antibacterials as well as experimental results from studies conducted in vitro. in animals and in humans. Pulse vs Continuous Antibiotic Infusions 72 It is evident from reviewing the literature that neither mode of administration is clearly superior to the other. The decision regarding the mode of administration must take into account the antibiotic being used, the bacteria, the patient and the infection, as well as the pharmacokinetics of the particular drug in the individual patient. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) are useful indicators of the relative in vitro effectiveness of antibiotics, but it is not clear what relevance these parameters have to the desired antibiotic concentrations in vivo. Furthermore, questions of serum vs tissue fluid concentrations, peak concentrations vs A UC, and free vs total concentration are all important issues to consider in assessing the optimal mode of administration. The importance of newer indices such as the post-antibiotic effect are now beginning to be recognised. A number of scientists are actively engaged in developing a system to identify the most appropriate mode of administration based upon the integration of an antibiotic's pharmacodynamics and pharmacokinetics. Within the next few years we anticipate that appropriate guidelines should have been developed to aid the optimisation of parenteral administration, at least for some antibiotics.
Clinical implications of antibiotic pharmacokinetic principles in the critically ill
Intensive Care Medicine, 2013
Successful antibiotic therapy in the critically ill requires sufficient drug concentrations at the site of infection that kill or suppress bacterial growth. The relationship between antibiotic exposure and achieving the above effects is referred to as pharmacokinetics/pharmacodynamics (PK/PD). The associated indices therefore provide logical targets for optimal antibiotic therapy. While dosing regimens to achieve such targets have largely been established from studies in animals and non-critically ill patients, they are often poorly validated in the ICU. Endothelial dysfunction, capillary leak, altered major organ blood flow, deranged plasma protein concentrations, extremes of body habitus, the application of extracorporeal support modalities, and a higher prevalence of intermediate susceptibility, independently, and in combination, significantly confound successful antibiotic treatment in this setting. As such, the prescription of standard doses are likely to result in sub-therapeutic concentrations, which in turn may promote treatment failure or the selection of resistant pathogens. This review article considers these issues in detail, summarizing the key changes in antibiotic PK/PD in the critically ill, and suggesting alternative dosing strategies that may improve antibiotic therapy in these challenging patients.
Biomedical Papers
Aims. Critically ill patients undergoing aggressive fluid resuscitation and treated empirically with hydrosoluble timedependent beta-lactam antibiotics are at risk for sub-therapeutic plasma concentrations. The aim of this study was to assess the impact of two covariates-creatinine clearance (Cl cr) and cumulative fluid balance (CFB) on pharmacokinetics/pharmacodynamics (PK/PD) target attainment within a week of treatment with meropenem (ME) or piperacillin/ tazobactam (PIP/TZB). Methods. In this prospective observational pharmacokinetic (PK) study, 18 critically ill patients admitted to a surgical Intensive Care Unit (ICU) were enrolled. The primary PK/PD target was free antibiotic concentrations above MIC at 100% of the dosing interval (100%fT>MIC) to obtain maximum bactericidal activity. Drug concentration was measured using liquid chromatography-tandem mass spectrometry. Results. The treatment of both 8 septic patients with IV extended ME dosing 2 g/3 h q8 h and 10 polytraumatized patients with IV intermittent PIP/TZB dosing 4.0/0.5 g q8 h was monitored. 8/18 patients (44%) manifested augmented renal clearence (ARC) where Cl cr ≥130 mL/min/1.73 m 2. Maximum changes were reported on days 2-3: the median positive CFB followed by the large median volume of distribution: Vd me =70.3 L (41.9-101.5), Vd pip = 46.8 L (39.7-60.0). 100%fT me >MIC was achieved in all patients on ME (aged ≥60 years), and only in two patients (non-ARC, aged ≥65 years) out of 10 on PIP/TZB. A mixed model analysis revealed positive relationship of CFB pip with Vd pip (P=0.021). Conclusion. Assuming that the positive correlation between CFB and Vd exists for piperacillin in the setting of the pathological state, then CFB should predict Vd pip across subjects at each and every time point.