Scoping review of drug dosing recommendations in sustained low-efficiency dialysis

The objective of this scoping review was to answer the question, "What has been published describing drug dosing in sustained low-efficiency dialysis (SLED)?" PubMed, Embase, and Scopus were searched on November 18, 2022. Methodology followed the Arksey and O'Malley framework for scoping reviews and Preferred Reporting Items for Systematic Reviews and Meta-Analysis Extension for Scoping Reviews guidelines. Two investigators independently screened abstracts and full-texts of citations identified related to drug dosing and SLED. Exclusion criteria included case reports, conference abstracts, pediatrics, treatment dialysis, and non-human subjects. A standardized data extraction sheet was used to collate and summarize data. The quality of evidence was evaluated by two investigators using the Mixed Methods Appraisal Tool. A total of 230 citations were identified for screening. Of these, 29 studies met criteria for inclusion after full-text review. Four drug groups including beta-lactam antibiotics, non-beta-lactam antibiotics, antifungals, and levetiracetam were identified. Dialysate rates, dialysis durations, and medication doses used varied widely across studies. Outcomes and pharmacokinetic parameters that were assessed were also heterogenous. Drug dosing in SLED is challenging and there is minimal evidence available to guide appropriate dosing. Larger studies are needed to more accurately determine how to appropriately dose medications in SLED. Therapeutic drug monitoring should be used in all patients on SLED when available.

Risk Factors Associated with Antibiotic Exposure Variability in Critically Ill Patients: A Systematic Review

(1) Background: Knowledge about the behavior of antibiotics in critically ill patients has been increasing in recent years. Some studies have concluded that a high percentage may be outside the therapeutic range. The most likely cause of this is the pharmacokinetic variability of critically ill patients, but it is not clear which factors have the greatest impact. The aim of this systematic review is to identify risk factors among critically ill patients that may exhibit significant pharmacokinetic alterations, compromising treatment efficacy and safety. (2) Methods: The search included the PubMed, Web of Science, and Embase databases. (3) Results: We identified 246 observational studies and ten clinical trials. The most studied risk factors in the literature were renal function, weight, age, sex, and renal replacement therapy. Risk factors with the greatest impact included renal function, weight, renal replacement therapy, age, protein or albumin levels, and APACHE or SAPS scores. (4) Conclusions: The review allows us to identify which critically ill patients are at a higher risk of not reaching therapeutic targets and helps us to recognize the extensive number of risk factors that have been studied, guiding their inclusion in future studies. It is essential to continue researching, especially in real clinical practice and with clinical outcomes.

Antimicrobial pharmacokinetics and dosing in critically ill adults receiving prolonged intermittent renal replacement therapy: A systematic review

Prolonged intermittent renal replacement therapy (PIRRT) is gaining popularity as a renal replacement modality in intensive care units, but there is a relative lack of guidance regarding antimicrobial clearance and dosing when compared with other modalities. The objectives of this systematic review were to: (1) identify and describe the pharmacokinetics (PK) of relevant antimicrobials used in critically ill adults receiving PIRRT, (2) evaluate the quality of evidence supporting these data, and (3) propose dosing recommendations based on the synthesis of these data. A search strategy for multiple databases was designed and executed to identify relevant published evidence describing the PK of antimicrobials used in critically ill adults receiving PIRRT. Quality assessment, evaluation of reporting, and relevant data extraction were conducted in duplicate. Synthesis of PK/pharmacodynamic (PD) outcomes, dosing recommendations from study authors, and physicochemical properties of included antibiotics were assessed by investigators in addition to the quality of evidence to develop dosing recommendations. Thirty-nine studies enrolling 452 patients met criteria for inclusion and provided PK and/or PD data for 20 antimicrobials in critically ill adults receiving PIRRT. Nineteen studies describe both PK and PD outcomes. Vancomycin (12 studies, 171 patients), meropenem (7 studies, 84 patients), and piperacillin/tazobactam (5 studies, 56 patients) were the most frequent antimicrobials encountered. The quality of evidence was deemed strong for 7/20 antimicrobials, and strong dosing recommendations were determined for 9/20 antimicrobials. This systematic review updates and addresses issues of quality in previous systematic reviews on this topic. Despite an overall low quality of evidence, strong recommendations were able to be made for almost half of the identified antimicrobials. Knowledge gaps persist for many antimicrobials, and higher quality studies (i.e., population PK studies with assessment of PD target attainment) are needed to address these gaps.

Antimicrobial Pharmacokinetics and Pharmacodynamics in Critical Care: Adjusting the Dose in Extracorporeal Circulation and to Prevent the Genesis of Multiresistant Bacteria

Critically ill patients suffering from severe infections are prone to pathophysiological pharmacokinetic changes that are frequently associated with inadequate antibiotic serum concentrations. Minimum inhibitory concentrations (MICs) of the causative pathogens tend to be higher in intensive care units. Both pharmacokinetic changes and high antibiotic resistance likely jeopardize the efficacy of treatment. The use of extracorporeal circulation devices to support hemodynamic, respiratory, or renal failure enables pharmacokinetic changes and makes it even more difficult to achieve an adequate antibiotic dose. Besides a clinical response, antibiotic pharmacokinetic optimization is important to reduce the selection of strains resistant to common antibiotics. In this review, we summarize the present knowledge regarding pharmacokinetic changes in critically ill patients and we discuss the effects of extra-corporeal devices on antibiotic treatment together with potential solutions.

Therapeutic Drug Monitoring of Antibiotic Drugs in Patients Receiving Continuous Renal Replacement Therapy or Intermittent Hemodialysis: A Critical Review

PURPOSE

Antibiotics are frequently used in patients receiving intermittent or continuous renal replacement therapy (RRT). Continuous renal replacement may alter the pharmacokinetics (PK) and the ability to achieve PK/pharmacodynamic (PD) targets. Therapeutic drug monitoring (TDM) could help evaluate drug exposure and guide antibiotic dosage adjustment. The present review describes recent TDM data on antibiotic exposure and PK/PD target attainment (TA) in patients receiving intermittent or continuous RRT, proposing practical guidelines for performing TDM.

METHODS

Studies on antibiotic TDM performed in patients receiving intermittent or continuous RRT published between 2000 and 2020 were searched and assessed. The authors focused on studies that reported data on PK/PD TA. TDM recommendations were based on clinically relevant PK/PD relationships and previously published guidelines.

RESULTS

In total, 2383 reports were retrieved. After excluding nonrelevant publications, 139 articles were selected. Overall, 107 studies reported PK/PD TA for 24 agents. Data were available for various intermittent and continuous RRT techniques. The study design, TDM practice, and definition of PK/PD targets were inconsistent across studies. Drug exposure and TA rates were highly variable. TDM seems to be necessary to control drug exposure in patients receiving intermittent and continuous RRT techniques, especially for antibiotics with narrow therapeutic margins and in critically ill patients. Practical recommendations can provide insights on relevant PK/PD targets, sampling, and timing of TDM for various antibiotic classes.

CONCLUSIONS

Highly variable antibiotic exposure and TA have been reported in patients receiving intermittent or continuous RRT. TDM for aminoglycosides, beta-lactams, glycopeptides, linezolid, and colistin is recommended in patients receiving RRT and suggested for daptomycin, fluoroquinolones, and tigecycline in critically ill patients on RRT.

Effects of Charged Oxime Reactivators on the HK-2 Cell Line in Renal Toxicity Screening

Oxime cholinesterase reactivators (oximes) are used to counteract organophosphate intoxication. Charged oximes are administered via intramuscular or intravenous injection when the majority of dose is unmetabolized and is excreted as urine. In this study, the effects of selected double charged oximes were determined in the HK-2 cell line as a model for renal toxicity screening. Some effects on dehydrogenase activity were found for obidoxime, asoxime (syn. HI-6), K027, and K203. The effects of K868 and K869 were found to be unreliable due to rapid degradation of both chlorinated oximes in the assay medium, resulting for K868 in an isoxazole-pyridinium product.

In vitro elimination of anti-infective drugs by the Seraph® 100 Microbind® affinity blood filter

Background

In August 2019, the European Union licensed the first ever haemoperfusion device aimed to reduce pathogens in the blood. The core of the adsorber consists of ultra-high molecular weight polyethylene beads with endpoint-attached heparin. These beads utilize pathogen inherent adhesion mechanisms to reduce pathogen load. So far, it is unknown whether the device has an effect on anti-infective drug concentrations. The aim of this study was to investigate the in vitro adsorption of multiple anti-infective drugs from human plasma.

Methods

In this in vitro study, 18 anti-infective drugs were administered to human donor plasma and pumped through the heparin-coated pathogen adsorber (Seraph^® 100 Microbind^®Affinity Blood Filter; ExThera Medical Corp., Martinez, CA, USA) at a plasma flow rate of 250 mL/min for 60 min. Pre- and post-adsorber plasma samples were quantified after 5, 15, 30 and 60 min.

Results

We found a reduction ratio (RR) in anti-infective plasma levels between −1% and 62%. This decrease occurred mainly in the first 5 min of the experiment (RR_0–5 −4 to 62%). Mean plasma clearance rates ranged between –11.93 mL/min (fluconazole) and 4.86 mL/min (clindamycin). The highest RRs were measured for aminoglycosides (tobramycin 62% and gentamycin 59%).

Conclusions

The elimination of anti-infective drugs by the Seraph is neglectable in all but 2 of 18 of the investigated substances. Aminoglycosides may be adsorbed by the device during their first pass.

Extensive Therapeutic Drug Monitoring of Colistin in Critically Ill Patients Reveals Undetected Risks

(1) Background: With the rise of multi-/pan-drug resistant (MDR/PDR) pathogens, the less utilized antibiotic Colistin has made a comeback. Colistin fell out of favor due to its small therapeutic range and high potential for toxicity. Today, it is used again as a last resort substance in treating MDR/PDR pathogens. Although new guidelines with detailed recommendations for Colistin dosing are available, finding the right dose in critically ill patients with renal failure remains difficult. Here, we evaluate the efficiency of the current guidelines' recommendations by using high resolution therapeutic drug monitoring of Colistin. (2) Methods: We analyzed plasma levels of Colistin and its prodrug colisthimethate sodium (CMS) in 779 samples, drawn from eight PDR-infected ICU patients, using a HPLC-MS/MS approach. The impact of renal function on proper Colistin target levels was assessed. (3) Results: CMS levels did not correlate with Colistin levels. Over-/Underdosing occurred regardless of renal function and mode of renal replacement therapy. Colistin elimination half-time appeared to be longer than previously reported. (4) Conclusion: Following dose recommendations from the most current guidelines does not necessarily lead to adequate Colistin plasma levels. Use of Colistin without therapeutic drug monitoring might be unsafe and guideline adherence does not warrant efficient target levels in critically ill patients.

Principles of Drug Dosing in Sustained Low Efficiency Dialysis (SLED) and Review of Antimicrobial Dosing Literature

The use of sustained low-efficiency dialysis (SLED) as a renal replacement modality has increased in critically ill patients with both acute kidney injury (AKI) and hemodynamic instability. Unfortunately, there is a paucity of data regarding the appropriate dosing of medications for patients undergoing SLED. Dose adjustment in SLED often requires interpretation of pharmacodynamics and pharmacokinetic factors and extrapolation based on dosing recommendations from other modes of renal replacement therapy (RRT). This review summarizes published trials of antimicrobial dose adjustment in SLED and discusses pharmacokinetic considerations specific to medication dosing in SLED. Preliminary recommendation is provided on selection of appropriate dosing for medications where published literature is unavailable.

[Pharmacokinetics and pharmacodynamics in extracorporeal renal replacement therapy]

Intermittent hemodialysis, continuous hemofiltration and prolonged daily dialysis are used for renal replacement therapy in the intensive care units. Independent of the replacement modality, antibiotic therapy must start with a high loading dose. Dose adjustment to the kidneys must follow 48 h later to prevent toxic accumulation. Dose recommendations on product labels are often underdosed. On continuous hemofiltration, meanwhile many intensivists administer a normal standard dose because the high filtration rate corresponds to a half-normal glomerular filtration rate. After intermittent hemodialysis, a dose similar to the loading dose will be needed. On day off dialysis, the maintenance dose must be adjusted to the failing kidney function. Immediately after prolonged daily dialysis, a loading dose should be given; with twice daily dosing the maintenance dose needs to be adjusted to kidney function. Therapeutic drug monitoring is recommended for gentamicin, vancomycin, piperacillin, meropenem and voriconazole. Due to pharmacodynamic reasons, the target concentration corresponds to the concentration producing the half-maximum effect. Accordingly, the target concentration is the normal peak for concentration-dependent action with bolus dosing. The target is the average steady-state concentration for antibiotics with time-dependent action and continuous infusion.