Continuous and 4 h infusion of amphotericin B: a comparative study involving high-risk haematology patients

Nephrotoxicity of continuous amphotericin B in critically ill patients with abdominal sepsis: a retrospective analysis with propensity score matching

BACKGROUND

Continuous infusion of conventional amphotericin B (CCAB) is used in ICUs for pre-emptive treatment of invasive fungal infections. Amphotericin B has previously been associated with nephrotoxicity.

OBJECTIVES

To investigate if CCAB with therapeutic drug monitoring (TDM) results in renal impairment over time in critically ill patients with abdominal sepsis.

PATIENTS AND METHODS

The study was conducted at mixed medical-surgical ICUs of two large teaching hospitals in the Netherlands. Consecutive patients who were treated on the ICUs between 2006 and 2019 for abdominal sepsis, with or without CCAB, were included. CCAB dosing was guided by TDM. Serum creatinine concentrations and renal failure scores of patients with CCAB treatment were compared with those without CCAB treatment. Excluded were: (i) patients treated with CCAB for less than 72 h; and (ii) patients with renal replacement therapy.

RESULTS

A total of 319 patients were included (185 treated with CCAB and 134 controls). A multiple linear regression model showed that the serum creatinine concentration was independent of CCAB treatment (β = -0.023; 95% CI = -12.2 to 7.2; P = 0.615). Propensity score matching resulted in 134 pairs of CCAB-treated and non-treated patients. Again, the analysis of these pairs showed that the cumulative CCAB dose was not associated with serum creatinine concentration during intensive care treatment (β = 0.299; 95% CI = -0.38 to 0.98; P = 0.388).

CONCLUSIONS

CCAB with TDM did not result in renal impairment over time in critically ill patients with abdominal sepsis.

Antifungal agents and the kidney: pharmacokinetics, clinical nephrotoxicity, and interactions

INTRODUCTION

Invasive fungal infections continue to be important causes of morbidity and mortality in severely ill and immunocompromised patient populations. The past three decades have seen a considerable expansion in antifungal drug research, resulting in the clinical development of different classes of antifungal agents with different pharmacologic properties. Among drug-specific characteristics of antifungal agents, renal disposition and nephrotoxicity are important clinical considerations as many patients requiring antifungal therapy have compromised organ functions or are receiving other potentially nephrotoxic medications.

AREAS COVERED

The present article reviews incidence, severity and mechanisms of nephrotoxicity associated with antifungal agents used for prevention and treatment of invasive fungal diseases by discussing distribution, metabolism, elimination and drug-related adverse events in the context of safety data from phase II and III clinical studies.

EXPERT OPINION

Based on the available data amphotericin B deoxycholate has the highest relative potential for nephrotoxicity, followed by the lipid formulations of amphotericin B, and, to a much lesser extent and by indirect mechanisms, the antifungal triazoles.

Preparation, Characterization, and Formulation Optimization of Ionic-Liquid-in-Water Nanoemulsions toward Systemic Delivery of Amphotericin B

Amphotericin B (AmB) is an antifungal agent that poses a challenge for intravenous drug delivery due to its hydrophobicity and severe side effects that are attributed to the self-aggregation of AmB in aqueous solution. To overcome this problem, we have rationally designed an ionic-liquid-in-water nanoemulsion drug delivery system that harnesses the unique properties of ionic liquids. The complex drug AmB serves as a model pharmaceutical agent to demonstrate the robustness of ionic-liquid-in-water nanoemulsions. High concentrations of AmB were solubilized in a new hydrophobic dicholinium-based ionic liquid. The absorption spectrum of AmB in an ionic liquid mixture and prepared nanoemulsion indicates AmB solubilization in the monomeric form. The hydrophobic ionic liquid exhibits high in vivo biocompatibility with zebrafish. The hemolytic activity of the AmB nanoemulsion was negligible, yet it maintained antifungal activity against Candida albicans. The preliminary results presented in this Communication indicate that ionic-liquid-in-water nanoemulsions may allow for the delivery of a variety of pharmaceuticals intravenously, broadening the scope of ionic liquids in the pharmaceutical sciences.

Mechanisms of antimicrobial-induced nephrotoxicity in children

Drug-induced nephrotoxicity is responsible for 20% to 60% of cases of acute kidney injury in hospitalized patients and is associated with increased morbidity and mortality in both children and adults. Antimicrobials are one of the most common classes of medications prescribed globally and also among the most common causes of nephrotoxicity. A broad range of antimicrobial agents have been associated with nephrotoxicity, but the features of kidney injury vary based on the agent, its mechanism of injury and the site of toxicity within the kidney. Distinguishing nephrotoxicity caused by an antimicrobial agent from other potential inciting factors is important to facilitate both early recognition of drug toxicity and prompt cessation of an offending drug, as well as to avoid unnecessary discontinuation of an innocuous therapy. This review will detail the different types of antimicrobial-induced nephrotoxicity: acute tubular necrosis, acute interstitial nephritis and obstructive nephropathy. It will also describe the mechanism of injury caused by specific antimicrobial agents and classes (vancomycin, aminoglycosides, polymyxins, antivirals, amphotericin B), highlight the toxicodynamics of these drugs and provide guidance on administration or monitoring practices that can mitigate toxicity, when known. Particular attention will be paid to paediatric patients, when applicable, in whom nephrotoxin exposure is an often-underappreciated cause of kidney injury.

Systematic review on the first line treatment of amphotericin B in critically ill adults with candidemia or invasive candidiasis

INTRODUCTION

Invasive candidiasis is the most common fungal infection affecting critically ill adults. International guidelines provide differing recommendations for first-line antifungal therapy, with echinocandins considered first-line in the majority. Amphotericin B has broad activity and low minimum inhibitory concentration resistance patterns across most Candida species and guidance away from its use should be supported by the available evidence. Areas Covered: A systematic literature review was conducted from August to September 2017 to determine whether treatment with echinocandins or other available drugs, namely voriconazole, confers a therapeutic or survival benefit over amphotericin B in critically ill adults with invasive candidiasis. Inclusion criteria were: (1) studies describing critically ill adults with invasive candidiasis, (2) studies describing therapeutic benefit or survival as an outcome, and (3) studies comparing amphotericin B, deoxycholate or lipid preparations, with any newer antifungal agent. Eight studies were included in the final review, incorporating 2352 unique patients. No difference in treatment efficacy or mortality outcomes in critically ill patients with invasive candidiasis receiving an amphotericin B formulation compared with those receiving an echinocandin or voriconazole was shown. Expert Commentary: We conclude that in the existing literature, there is no evidence that choice between echinocandins, voriconazole, or amphotericin B formulations as first-line therapy for critically ill adults with invasive candidiasis is associated with a therapeutic or survival benefit. Clinicians must therefore consider other factors in the selection of first-line therapy.

Pharmacokinetics of antifungal drugs: practical implications for optimized treatment of patients

Introduction

Because of the high mortality of invasive fungal infections (IFIs), appropriate exposure to antifungals appears to be crucial for therapeutic efficacy and safety.

Materials and methods

This review summarises published pharmacokinetic data on systemically administered antifungals focusing on co-morbidities, target-site penetration, and combination antifungal therapy.

Conclusions and discussion

Amphotericin B is eliminated unchanged via urine and faeces. Flucytosine and fluconazole display low protein binding and are eliminated by the kidney. Itraconazole, voriconazole, posaconazole and isavuconazole are metabolised in the liver. Azoles are substrates and inhibitors of cytochrome P450 (CYP) isoenzymes and are therefore involved in numerous drug–drug interactions. Anidulafungin is spontaneously degraded in the plasma. Caspofungin and micafungin undergo enzymatic metabolism in the liver, which is independent of CYP. Although several drug–drug interactions occur during caspofungin and micafungin treatment, echinocandins display a lower potential for drug–drug interactions. Flucytosine and azoles penetrate into most of relevant tissues. Amphotericin B accumulates in the liver and in the spleen. Its concentrations in lung and kidney are intermediate and relatively low myocardium and brain. Tissue distribution of echinocandins is similar to that of amphotericin. Combination antifungal therapy is established for cryptococcosis but controversial in other IFIs such as invasive aspergillosis and mucormycosis.

Invasive Fungal Infections in the Critically Ill Patient

Invasive fungal infections have become an increasingly prevalent and disturbing problem in critically ill patients. The advent of broad-spectrum antibacterial therapy and immunosuppressant therapy, among other factors such as mechanical ventilation, places the intensive care patient at significant risk for infection with pathogenic fungi. Most patients who become infected with invasive fungi, especially Candida species, have been previously colonized with the offending organism, lending to the notion that colonization precedes infection inmany cases. Despite an ever-increasing array of antifungal therapy for these infections, mortality rates remain extremely high, especially when the bloodstream is the primary site of infection. In addition, a shift toward more resistant pathogens such asCandida glabrata, Candida krusei, and moldswill provide clinicianswith therapeutic challenges for many years. The wide variation in acquisition cost across antifungal agents adds an additional layer of complexity to clinical decision making. Newer antifungal agents, each with its own advantages and disadvantages, have become available in recent years. Placing each agent in its appropriate niche is a dilemma that has yet to be solved.

Physical characterization and in vivo pharmacokinetic study of self-assembling amphotericin B-loaded lecithin-based mixed polymeric micelles

To alleviate the inherent problems of amphotericin B (AmB), such as poor water solubility and nephrotoxicity, a novel self-assembling mixed polymeric micelle delivery system based on lecithin and combined with amphiphilic polymers, Pluronic^®, Kolliphor^®, d-alpha tocopheryl polyethylene glycol succinate, and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy(poly(ethylene glycol)-2000 (DSPE-PEG2K) was developed. An optimal formulation (Ambicelles) composed of AmB:lecithin:DSPE-PEG2K in a 1:1:10 weight ratio was obtained. The particle size, polydispersion index, drug encapsulation efficiency, and drug loading were 187.20±10.55 nm, 0.51±0.017, 90.14%, and 7.51%, respectively, and the solubility was increased from 0.001 to 5 mg/mL. Compared with that of Fungizone^®, the bioavailability of Ambicelles administered intravenously and orally increased 2.18- and 1.50-fold, respectively. Regarding the in vitro cytotoxicity, Ambicelles had a higher cell viability than free AmB solution or Fungizone^® did. With pretreatment of 50 μg/mL ethanolic extract of Taiwanofungus camphoratus followed by AmB to HT29 colon cancer cells, the 50% inhibitory concentration of AmB solution was 12 μg/mL, whereas that of Ambicelles was 1 μg/mL, indicating that Ambicelles exerted a greater synergistic anticancer effect.

Pharmacokinetics and pharmacodynamics of antifungals in children and their clinical implications

Invasive fungal infections are a significant cause of morbidity and mortality in children. Successful management of these systemic infections requires identification of the causative pathogen, appropriate antifungal selection, and optimisation of its pharmacokinetic and pharmacodynamic properties to maximise its antifungal activity and minimise toxicity and the emergence of resistance. This review highlights salient scientific advancements in paediatric antifungal pharmacotherapies and focuses on pharmacokinetic and pharmacodynamic studies that underpin current clinical decision making. Four classes of drugs are widely used in the treatment of invasive fungal infections in children, including the polyenes, triazoles, pyrimidine analogues and echinocandins. Several lipidic formulations of the polyene amphotericin B have substantially reduced the toxicity associated with the traditional amphotericin B formulation. Monotherapy with the pyrimidine analogue flucytosine rapidly promotes the emergence of resistance and cannot be recommended. However, when used in combination with other antifungal agents, therapeutic drug monitoring of flucytosine has been shown to reduce high peak flucytosine concentrations, which are strongly associated with toxicity. The triazoles feature large inter-individual pharmacokinetic variability, although this pattern is less pronounced with fluconazole. In clinical trials, posaconazole was associated with fewer adverse effects than other members of the triazole family, though both posaconazole and itraconazole display erratic absorption that is influenced by gastric pH and the gastric emptying rate. Limited data suggest that the clinical response to therapy may be improved with higher plasma posaconazole and itraconazole concentrations. For voriconazole, pharmacokinetic studies among children have revealed that children require twice the recommended adult dose to achieve comparable blood concentrations. Voriconazole clearance is also affected by the cytochrome P450 (CYP) 2C19 genotype and hepatic impairment. Therapeutic drug monitoring is recommended as voriconazole pharmacokinetics are highly variable and small dose increases can result in marked changes in plasma concentrations. For the echinocandins, the primary source of pharmacokinetic variability stems from an age-dependent decrease in clearance with increasing age. Consequently, young children require larger doses per kilogram of body weight than older children and adults. Routine therapeutic drug monitoring for the echinocandins is not recommended. The effectiveness of many systemic antifungal agents has been correlated with pharmacodynamic targets in in vitro and in murine models of invasive candidiasis and aspergillosis. Further study is needed to translate these findings into optimal dosing regimens for children and to understand how these agents interact when multiple antifungal agents are used in combination.

Antifungal pharmacokinetics and pharmacodynamics

Successful treatment of infectious diseases requires choice of the most suitable antimicrobial agent, comprising consideration of drug pharmacokinetics (PK), including penetration into infection site, pathogen susceptibility, optimal route of drug administration, drug dose, frequency of administration, duration of therapy, and drug toxicity. Antimicrobial pharmacokinetic/pharmacodynamic (PK/PD) studies consider these variables and have been useful in drug development, optimizing dosing regimens, determining susceptibility breakpoints, and limiting toxicity of antifungal therapy. Here the concepts of antifungal PK/PD studies are reviewed, with emphasis on methodology and application. The initial sections of this review focus on principles and methodology. Then the pharmacodynamics of each major antifungal drug class (polyenes, flucytosine, azoles, and echinocandins) is discussed. Finally, the review discusses novel areas of pharmacodynamic investigation in the study and application of combination therapy.

continuous versus conventional infusion of amphotericin B deoxycholate: a meta-analysis

Background

Treatment with Amphotericin B (AmB) deoxycholate, which is still used widely, particularly in low-resource countries, has been challenged due to nephrotoxicity. We sought to study whether continuous infusion of AmB deoxycholate reduces nephrotoxicity retaining, however, the effectiveness of the drug.

Methods

PubMed and Scopus databases were systematically searched to identify studies comparing the outcomes of patients receiving 24-h infusion of AmB (“continuous group”) and those receiving 2–6-h infusion of AmB (“conventional group”). Nephrotoxicity and all-cause mortality were the primary outcomes of the review, while treatment failure was the secondary outcome.

Results

Five studies met the inclusion criteria; one randomized controlled trial, two prospective cohort studies, and two retrospective cohort studies. The majority of patients were neutropenic with an underlying hematologic malignancy. All 5 studies (392 patients) provided data regarding the development of nephrotoxicity. A non-significant trend towards lower nephrotoxicity was observed for patients receiving continuous infusion of AmB compared with those receiving conventional infusion [RR = 0.61 (95% CI 0.36, 1.02)]. Four studies (365 patients) provided data regarding mortality; no relevant difference was detected between patients receiving continuous and those receiving conventional infusion of AmB [RR = 0.81 (95% CI 0.36, 1.83)]. Data on treatment failure of the two methods of administration was insufficient for meaningful conclusions.

Conclusion

The available evidence from mainly non-randomized studies suggests that continuous infusion of AmB deoxycholate might offer an advantage over the conventional infusion regarding the development of nephrotoxicity, without compromising patient survival. Further randomized studies are needed to investigate this issue.

Encapsulation and release of Amphotericin B from an ABC triblock fluorous copolymer

PURPOSE

PEG-phospholipid-based micelles have been successfully used for the solubilization of several hydrophobic drugs but generally lack sustained stability in blood. Our novel PEG-Fluorocarbon-DSPE polymers were designed to increase stability and improve time-release properties of drug-loaded micelles.

METHODS

Novel ABC fluorous copolymers were synthesized, characterized, and used for encapsulation release of amphotericin B. FRET studies were used to study micelle stability.

RESULTS

The micelles formed by the new polymers showed lower critical micelle concentrations and higher viscosity cores than those formed by the polymers lacking the fluorous block. FRET studies indicated that fluorocarbon-containing micelles had increased stability in presence of human serum. Physicochemical properties and in vitro release profile of micelles loaded with Amphotericin B (AmB) were studied.

CONCLUSIONS

The effect of PEG length and fluorocarbon incorporation were investigated. The shorter hydrophilic PEG2K induced greater stability than PEG5K by decreasing the proportion of hydrophilic block of the polymer. The fluorocarbon placed between hydrophilic and hydrophobic block formed a fluorous shell contributing to the enhanced thermodynamic stability of micelles and to the drug sustained release. Polymer mPEG2K-F(10)-DSPE, bearing both a fluorocarbon block and a shorter mPEG, showed the greatest stability and the longest half-life for AmB release.

Fungal infections: their diagnosis and treatment in transplant recipients

Systemic fungal infections typically occur in individuals who are seriously ill with recognized risk factors such as those frequently found in transplant recipients. Unfortunately, they are often diagnosed late, when the efficacy of the available treatments is low, often less than 50%, and the cost in terms of lives lost, hospital length of stay, and total hospital costs is substantially increased. The application of antifungal therapies associated with reported efficacy rates greater than 50% are those used prophylactically. When used prophylactically, these infections are reduced in greater than 95% of the expected cases. The choice of a prophylactic agent should be based upon its ease of administration, lack of adverse effects, reduced likelihood of potential drug interactions, and its efficacy in patients with established risk factors and comorbid disease processes that include renal, hepatic, and chronic pulmonary disease. The indications for the use of currently available antifungal agents, their adverse effects, drug interactions, ease of dosing, and applicability in patients with preexisting disease states, and especially in liver transplant recipients, are presented in this paper.

Multidisciplinary approach to the treatment of invasive fungal infections in adult patients. Prophylaxis, empirical, preemptive or targeted therapy, which is the best in the different hosts?

The high morbidity, mortality, and health care costs associated with invasive fungal infections, especially in the critical care setting and immunocompromised host, have made it an excellent target for prophylactic, empiric, and preemptive therapy interventions principally based on early identification of risk factors. Early diagnosis and treatment are associated with a better prognosis. In the last years there have been important developments in antifungal pharmacotherapy. An approach to the new diagnosis tools in the clinical mycology laboratory and an analysis of the use new antifungal agents and its application in different clinical situations has been made. Furthermore, an attempt of developing a state of the art in each clinical scenario (critically ill, hematological, and solid organ transplant patients) has been performed, trying to choose the best strategy for each clinical situation (prophylaxis, pre-emptive, empirical, or targeted therapy). The high mortality rates in these settings make mandatory the application of early de-escalation therapy in critically ill patients with fungal infection. In addition, the possibility of antifungal combination therapy might be considered in solid organ transplant and hematological patients.

Continuous infusion of amphotericin B deoxycholate: an innovative, low-cost strategy in antifungal treatment

The combination of amphotericin B and sodium deoxycholate is the formulation most used in clinical practice. The development of new agents such as amphotericin with lipid formulations, caspofungin, voriconazole and other azolic derivatives, promoted alternatives to amphotericin B deoxycholate. However, because of the high cost of these new drugs, their use is difficult in a scenario of limited resources. A few strategies have been devised to make the use of amphotericin B deoxycholate less toxic. In this review, we seek to describe the accumulated knowledge about this molecule, with focus on its use in continuous infusion, which appears to be an alternative to reduce toxicity, while maintaining its clinical efficacy.

Antifungal treatment strategies in patients with haematological diseases or cancer: from prophylaxis to empirical, pre-emptive and targeted therapy

Immunocompromised patients have a high risk for invasive fungal diseases (IFDs). These infections are mostly life-threatening and an early diagnosis and initiation of appropriate antifungal therapy are essential for the clinical outcome. Empirical treatment is regarded as the standard of care for granulocytopenic patients who remain febrile despite broad-spectrum antibiotics. However, this strategy can bear a risk of overtreatment and subsequently induce toxicities and unnecessary treatment costs. Pre-emptive antifungal therapy is now increasingly used to close the time gap between delayed initiation for proven disease and empirical treatment for anticipated infection without further laboratory or radiological evidence of fungal disease. Currently, some new non-invasive microbiological and laboratory methods, like the Aspergillus-galactomannan sandwich-enzyme immunoassay (Aspergillus GM-ELISA), 1,3-β-D-glucan assay or PCR techniques have been developed for a better diagnosis and determination of target patients. The current diagnostic approaches to fungal infections and the role of the revised definitions for invasive fungal infections, now IFDs, will be discussed in this review as well as old and emerging approaches to empirical, pre-emptive and targeted antifungal therapies in patients with haemato-oncological malignancies.

To treat or not to treat--critically ill patients with candiduria

The prevalence of candiduria has increased in patients admitted to intensive care units (ICUs) and it has emerged as a common nosocomial infection among critically ill patients. Generally, urinary candidiasis should be regarded as a risk factor for invasive candidiasis, but not as a disease that needs to be treated on its own. However, decision-making in critically ill patients with candiduria may become a balancing act, because candiduria may be the only indication for invasive candidaemia with significant morbidity and mortality. Of further concern, there is a worldwide increase in the incidence of non-albicans spp. isolated from urine with highly variable susceptibility to fluconazole, which has been the first-line therapy for Candida infections during the last decades. This article discusses everyday problems with urinary candidiasis in interdisciplinary ICUs.

Alternate-day versus once-daily administration of amphotericin B in the treatment of cryptococcal meningitis: A randomized controlled trial

Animal studies and case series have demonstrated the dose-dependent efficacy and long half-life of amphotericin B deoxycholate (ABd), providing the rationale for our randomized controlled study to compare once-daily (OD) (1 mg/kg) and alternate-d (AD) (2 mg/kg) administration of ABd in the treatment of cryptococcal meningitis in patients with AIDS hospitalized at King Chulalongkorn Memorial Hospital, Thailand, from 2003 to 2004. Of 28 patients, 15 and 13 received OD and AD administration, respectively. There was no significant difference between the 2 groups regarding the demography, clinical features, and laboratory data. After 2 weeks of the intensive-phase treatment, there was no significant difference in the clinical response between the OD (80%) and AD (76.9%) groups. Mycological response was observed in 33.3% and 10% of patients in the OD and AD groups, respectively (p = 0.3). There was no difference in nephrotoxicity and infusion-related events. In conclusion, this is the first randomized controlled study comparing OD and AD administration of ABd in the treatment of cryptococcal meningitis. Although our study was not sufficiently powered to draw conclusions on clinical efficacy and toxicities, the results are encouraging and should warrant further clinical trials evaluating the efficacy and adverse effects with a larger sample size.

Therapeutic strategies for invasive fungal infections in neonatal and pediatric patients

Invasive Candida and Aspergillus infections are the most commonly encountered fungal infections. They appear to be life threatening in the setting of profound immunosuppression, whereas cases that are resistant to antifungal therapy are occasionally encountered. Novel antifungal triazole and echinocandin agents appear to exhibit good activity as first-line or salvage therapy, whereas the use of amphotericin B formulations is particularly valuable in neonates. Significant differences in toxicity have been demonstrated among various antifungal agents with in vitro activity from available comparative data on fungal infections in children: however, no clear difference in treatment efficacy has been demonstrated. However, very little data are available about neonates. Host factors and responsible fungal species most frequently guide the choice of therapy.

Recommendations for the treatment of established fungal infections

Evidence-based guidelines for the treatment of established fungal infections in the adult haematology/oncology setting were developed by a national consensus working group representing clinicians, pharmacists and microbiologists. These updated guidelines replace the previous guidelines published in the Internal Medicine Journal by Slavin et al. in 2004. The guidelines are pathogen-specific and cover the treatment of the most common fungal infections including candidiasis, aspergillosis, cryptococcosis, zygomycosis, fusariosis, scedosporiosis, and dermatophytosis. Recommendations are provided for management of refractory disease or salvage therapies, and special sites of infections such as the cerebral nervous system and the eye. Because of the widespread use newer broad-spectrum triazoles in prophylaxis and empiric therapy, these guidelines should be implemented in concert with the updated prophylaxis and empiric therapy guidelines published by this group.

Combination antifungal therapy involving amphotericin B, rapamycin and 5-fluorocytosine using PEG-phospholipid micelles

PURPOSE

Rapamycin and 5-fluorocytosine (5-FC) are antifungal agents with unique mechanisms of activity, with potential for cooperative interaction with AmB. Combination antifungal therapy involving conventional AmB has been restricted by poor physical stability and compatibility with antifungal drugs and vehicles.

METHODS

AmB and rapamycin were encapsulated in 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy poly(ethylene glycol) (PEG-DSPE) micelles using a solvent evaporation method. The physical stability of micelle encapsulated AmB and rapamycin with 5-FC and saline was evaluated using dynamic light scattering (DLS). In vitro susceptibility of Candida albicans isolates to 5-FC and PEG-DSPE micelle solubilized AmB and rapamycin has been evaluated. Interactive effects have been quantified using a checkerboard layout.

RESULTS

In contrast with conventional AmB, PEG-DSPE micelles encapsulating AmB and rapamycin are compatible with saline and 5-FC over 12 h. The solubilized drugs retain high level of potency in vitro. The combination of solubilized AmB and rapamycin was indifferent, as fractional inhibitory concentration (FIC) index and combination index (CI) values were approximately 1. Combinations of solubilized AmB or rapamycin with 5-FC, and the three-drug combination were moderately synergistic since the FIC index and CI values were consistent less than 1.

CONCLUSIONS

These results indicate that AmB solubilized in PEG-DSPE micelles is compatible with solubilized rapamycin and 5-FC. The indifferent or moderately synergistic activity of combinations is encouraging and warrants further investigation in appropriate rodent models.

Management of Candida infections in the adult intensive care unit

The epidemiology of Candida infection in intensive care units (ICUs) and the management strategies for such infections in non-neutropenic intensive care patients are discussed in this review. Candida species are one of the leading causes of nosocomial bloodstream infections and a significant cause of morbidity in patients admitted to the ICU. Prophylactic, pre-emptive and empiric treatment strategies for Candida infections have been explored in ICU patients. Routine prophylaxis should not be administered to the whole population of ICU patients, because the concerns about the selection of azole-resistant Candida strains or the induction of resistance are justified. Treatment of fungal infections is now possible with newer antifungal agents, including newer azoles (e.g., voriconazole, posaconazole) and echinocandins (e.g., micafungin, anidulafungin). However, there is a critical need for improvement in diagnosis of invasive Candida infection in order to provide clinicians the opportunity to intervene earlier in the diseases course.

Effect of cholesterol on the release of amphotericin B from PEG-phospholipid micelles

Micelles formed from PEG-DSPE solubilize high levels of the poorly water-soluble antifungal amphotericin B (AmB). AmB release from PEG-DSPE micelles is slow in buffer but remarkably rapid in the presence of bovine serum albumin (BSA). Sequential changes in the absorbance spectrum of AmB in PEG-DSPE micelles point to a rapid dissociation of incorporated drug in the presence of BSA. In this context, we have studied micelles formed from PEG-DSPE which coincorporate cholesterol (PEG-DSPE|cholesterol). (1)H NMR measurements point to a lower mobility of lipid in PEG-DSPE|cholesterol micelles compared to PEG-DSPE micelles. The absorbance spectrum of AmB incorporated in PEG-DSPE|cholesterol micelles is distinct from that in PEG-DSPE micelles, which may point to differences in the drug-micelle interaction. AmB release from PEG-DSPE|cholesterol micelles is slow in buffer and in the presence of BSA. The absorption spectrum of AmB in PEG-DSPE|cholesterol micelles remained unchanged in BSA, further supporting stable incorporation and the slow release from the carrier.

Antifungal therapy in children with invasive fungal infections: a systematic review

Invasive fungal infections are associated with significant morbidity and mortality. Differences between children and adults are reported, yet few trials of antifungal agents have been performed in pediatric populations. We performed a systematic review of the literature to guide appropriate pediatric treatment recommendations. From available trials that compared antifungal agents in either prolonged febrile neutropenia or invasive candidal or Aspergillus infection, no clear difference in treatment efficacy was demonstrated, although few trials were adequately powered. Differing antifungal pharmacokinetics between children and adults were demonstrated, requiring dose modification. Significant differences in toxicity, particularly nephrotoxicity, were identified between classes of antifungal agents. Therapy needs to be guided by the pathogen or suspected pathogens, the degree of immunosuppression, comorbidities (particularly renal dysfunction), concurrent nephrotoxins, and the expected length of therapy.

Economic evaluation of the prevention and management of systemic fungal infections in neutropenic patients

Systemic fungal infections in neutropenic patients remain a clinical problem that is associated with morbidity and mortality. Continuing efforts are being made to develop improved (i.e., more effective or safe) drugs, and several new treatments have recently become available. These have increased the therapeutic options available to clinicians to address the problem of systemic fungal infections. Therapeutic choices are difficult when taking into account aspects of efficacy, safety and costs that are associated with the available alternatives. This review summarises the present status of health economic knowledge of the standard therapies that have been available for many years, and also reports on the most recent health economic evidence available for the newly developed treatment alternatives.

Cryptococcal disease and HIV infection

In the era of highly active antiretroviral therapy for the treatment of HIV infection, the dramatic reductions in mortality and morbidity associated with immune reconstitution have included a marked decline in the incidence of opportunistic infections. Cryptococcus neoformans is a yeast that causes predominantly neurological disease in immunocompromised individuals, in particular those with HIV infection. It continues to be an important diagnosis in developing areas and amongst late presenters in parts of the world with access to highly active antiretroviral therapy. This article reviews the epidemiology, clinical features and management of cryptococcal disease in HIV-infected patients, particularly focusing on the history of, current guidelines for and future developments in antifungal therapy.

Tratamiento de las infecciones fúngicas invasoras

Invasive fungal infections have increased progressively in the last decades, producing elevated morbidity and mortality. In recent years, there have been numerous advances in the treatment of these diseases, with the introduction of new drugs in clinical practice and the information derived from several types of studies. This has improved the prognosis of some invasive fungal infections and increased the therapeutic options in various clinical situations. This new knowledge must be assessed to determine its application in clinical practice, taking into account available scientific evidence and clinical experience. With this aim, the Andalusian Society of Infectious Diseases has developed this consensus document containing recommendations for the treatment of the invasive fungal infections.

In vitro pharmacodynamics of rapid versus continuous infusion of amphotericin B deoxycholate against Candida species in the presence of human serum albumin

BACKGROUND

Recent open label studies have suggested that dosing amphotericin B (AMB) by continuous infusion (CI) may reduce drug-associated infusion reactions and nephrotoxicity. In vitro and in vivo pharmacodynamic (PD) data, however, do not consistently support the concept of CI dosing based on the concentration-dependent activity of this agent and in vitro studies with AMB rarely account for the drug's high degree of protein binding. Therefore, we compared the PD activity of simulated continuous versus rapid infusion strategies of AMB in killing of AMB-susceptible and -resistant Candida species using an in vitro pharmacodynamic model.

METHODS

Time-kill curves were performed with Candida albicans (Etest MIC 0.38 mg/L) and Candida lusitaniae (MIC 1.5 mg/L) at AMB concentrations between 0 and 16 mg/L in the absence and presence of 4 and 8% human serum albumin (HSA). A one-compartment in vitro pharmacodynamic model was used to simulate the steady-state PK parameters of bolus and CI AMB.

RESULTS

The fungicidal activity of AMB was attenuated by the presence of HSA for both Candida species tested. The EC50 for each isolate significantly increased in the presence of 4% HSA (P<0.05), and fungicidal activity was completely abated for C. lusitaniae when HSA concentrations were increased to 8%. No substantial differences in the rate or extent of AMB killing were observed between rapid infusion or CI dosing and neither regimen produced fungicidal activity in the presence of HSA.

CONCLUSIONS

The presence of HSA changes the in vitro PD of AMB. In our model, CI and rapid infusion dosing of AMB exhibited similar activity when attempts were made to correct for protein binding that is likely to occur in vivo.

Coccidioidomycosis in Persons Infected with HIV Type 1

Coccidioidomycosis is a recognized opportunistic infection among persons infected with human immunodeficiency virus (HIV). Early in the HIV epidemic, most cases presented as overwhelming diffuse pulmonary disease with a high mortality rate. Although these cases are still seen, patients without significant immunodeficiency frequently present with a community-acquired pneumonia syndrome. Diagnosis can be established by cytological staining, culture, or serologic testing. All patients with HIV infection and symptomatic coccidioidomycosis should be treated with antifungal therapy. Severe cases frequently require a combination of therapy with amphotericin B and a triazole antifungal. Therapy for at least 1 year is recommended, but for patients with a focal pulmonary infection and peripheral blood CD4 lymphocyte counts of >250 cells/microL, it may be reasonable to stop therapy after this time. Other manifestations of coccidioidomycosis require prolonged therapy, and life-long treatment is recommended for persons with meningitis.

Tratamiento antifúngico empírico en pacientes seleccionados con fiebre persistente y neutropenia

Empirical antifungal treatment (EAT) in neutropenia is mainly aimed at improving the poor prognosis of patients with invasive fungal infection through early treatment. The Infectious Diseases Society of America recommends initiating EAT in patients with persistent fever after 5-7 days of antibacterial treatment, and in those in whom remission of neutropenia is not imminent. Nevertheless, EAT has not been shown to be more effective than a placebo, it does not show better results than directed antifungal treatment, its effectiveness is minimal, it is not innocuous, and it is not very efficient with the use of most antifungal agents. All considered, we believe that the aforementioned recommendation for EAT treatment is unjustified. In its place we propose the application of EAT in patients selected on the basis of clinical criteria and risk factors.