Comparison of the toxicity of amphotericin B in 5% dextrose with that of amphotericin B in fat emulsion in a randomized trial with cancer patients

Polyene Antibiotics Physical Chemistry and Their Effect on Lipid Membranes; Impacting Biological Processes and Medical Applications

This review examined a collection of studies regarding the molecular properties of some polyene antibiotic molecules as well as their properties in solution and in particular environmental conditions. We also looked into the proposed mechanism of action of polyenes, where membrane properties play a crucial role. Given the interest in polyene antibiotics as therapeutic agents, we looked into alternative ways of reducing their collateral toxicity, including semi-synthesis of derivatives and new formulations. We follow with studies on the role of membrane structure and, finally, recent developments regarding the most important clinical applications of these compounds.

Efficacy of Intralipid infusion in reducing amphotericin-B-associated nephrotoxicity in head and neck invasive fungal infection: A randomized, controlled trial

Amphotericin B deoxycholate (ABD) is the best therapeutic agent available for the treatment of most systemic fungal infections. However, some untoward adverse effects such as nephrotoxicity may limit its appropriate therapeutic use. We conducted a randomized, controlled trial ofthe infusion of fat emulsion (Intralipid) shortly after the infusion of ABD to evaluate its effects on reducing ABD-associated nephrotoxicity. Our patient population was made up of 31 patients who were randomized into two groups: an intervention group (n = 16) and a control group (15 patients). There were no statistically significant differences between the two groups in demographic or clinical variables. All patients received 1mg/kg/day of ABD in dextrose 5%. In addition, the patients in the intervention arm received Intralipid 10%, which was started as soon as possible within 1 hour after the infusion of ABD. ABD-associated nephrotoxicity was defined as a minimum 50% increase in baseline serum creatinine to a minimum of 2mg/dl. We also measured daily serum creatinine changes during the first 2 weeks of treatment, and we compared some other relevant indices of renal function, as well as ABD-related hypokalemia. We found no statistically significant differences between the two treatments in terms of ABD-associated nephrotoxicity or any of the other indices. We conclude that the administration of Intralipid 10% early after infusion of ABD in dextrose 5% does not have any effect in decreasing ABD-associated nephrotoxicity or hypokalemia.

Efficacy and safety of amphotericin B formulations: a network meta-analysis and a multicriteria decision analysis

Objectives

Despite its broad spectrum, conventional amphotericin B (AB) is associated with serious adverse events. Lipid-based formulations may offer safer options. We aimed to synthesize the evidence of efficacy and safety of AB formulations.

Methods

We performed a systematic review and network meta-analysis (NMA) to compare all available formulations: conventional AB; lipid complex or ABLC; colloidal dispersion or ABCD; liposomal or LAB; AB in Intralipid. Randomized controlled trials were searched in four databases. Cure, fever, chills, nephrotoxicity, death and drug discontinuation were assessed. NMA was based on Bayesian methods accounting for direct and indirect comparisons. Probability ranks estimating the best formulation were built for each outcome. The relative benefit–risk of formulations was assessed with stochastic multicriteria acceptability analyses (SMAA).

Key findings

We identified 25 trials (n = 2996). No significant differences among drugs were observed for cure or death. All lipid-based formulations were safer than conventional AB for nephrotoxicity. AB-Intralipid was more tolerable than conventional AB and caused less chills than ABCD. AB-Intralipid was the best therapy (>60%) regarding nephrotoxicity, fever, chills and discontinuation. The scenario from SMAA favoured AB-Intralipid (81% acceptability). Conventional AB was secondary to all lipid-based formulations.

Conclusions

Amphotericin B-Intralipid was identified as safer, cost-saving treatment in comparison with other formulations.

Evaluation of intravenous regional perfusion with amphotericin B and dimethylsulfoxide to treat horses for pythiosis of a limb

BACKGROUND

Treatment for horses with pythiosis of a limb is challenging. This study aims to evaluate the effects of administering amphotericin B in a 10 % solution of dimethylsulfoxide by intravenous regional limb perfusion (IRLP) to treat horses for cutaneous pythiosis of a limb.

RESULTS

All 15 of the horses treated had complete resolutions of their lesion between 6 to 9 weeks after a single IRLP treatment. No complications were observed at the site of venipuncture for IRLP. Before initiation of treatment, there was anemia and marked leucocytosis which resolved following treatment. Serum biochemistry showed no significant changes.

CONCLUSIONS

IRLP administration of amphotericin B in a 10 % DMSO solution was easily performed, relatively inexpensive and an effective treatment for treating horses for pythiosis of a limb and resolved the infection with no complications.

Incidence, Predictors, and Impact on Hospital Mortality of Amphotericin B Nephrotoxicity Defined Using Newer Acute Kidney Injury Diagnostic Criteria

Studies on amphotericin B (AmB) nephrotoxicity use diverse definitions of acute kidney injury (AKI). Here, we used the new Kidney Disease Improving Global Outcome (KDIGO) system to describe the incidence, predictors, and impact of AmB-induced AKI on hospital mortality in 162 patients treated with AmB (120 with deoxycholate preparation and 42 with liposomal preparation). KDIGO stage 1 requires an absolute increase of ≥0.3 mg/dl or ≥1.5× over baseline serum creatinine (SCr), while stage 2 requires ≥2×, and stage 3 requires ≥3×. A binary KDIGO definition (KDIGObin) corresponds to stage ≥1. For comparison, we included two definitions of AKI traditionally utilized in nephrotoxicity studies: ≥0.5 mg/dl (NT0.5) and ≥2× (NT2×) increase in baseline SCr. The overall incidence of AmB-induced AKI by KDIGObin was 58.6% (stage 1, 30.9%; stage 2, 18.5%; stage 3, 9.3%). Predictors of AKI by KDIGObin were older age and use of furosemide and angiotensin-converting enzyme inhibitor (ACE-I). Traditional criteria detected lower incidences of AKI, at 45.1% (NT0.5) and 27.8% (NT2×). Predictors of AKI by traditional criteria were older age and use of vancomycin (NT0.5) and use of vancomycin and vasopressors (NT2×). KDIGObin detected AKI 2 days earlier than the most sensitive traditional criterion. However, only traditional criteria were associated with intensive care unit (ICU) admission, mechanical ventilation, and mortality. In conclusion, the increase in sensitivity of KDIGObin is accompanied by a loss of specificity and ability to predict outcomes. Prospective studies are required to weigh the potential gain from early AKI detection against the potential loss from undue changes in management in patients with subtle elevations in SCr.

Inhibition of biofilm formation and lipase in Candida albicans by culture filtrate of Staphylococcus epidermidis in vitro

Background:

Candida spp. are fourth most common cause of bloodstream infection in developed countries and emerging agents of fungemia in developing countries, with considerable attributable mortality. Candidemia is associated with the formation of complex, structured microbial communities called biofilms. Biofilm formation makes treatment difficult due to improper drug penetration and factors like high cost and adverse effects of antifungal drugs available. Hence, low-cost alternatives are urgently required to treat device-associated invasive candidiasis.

Objectives:

To study the effect of culture filtrate of Staphylococcus epidermidis on biofilm formation and lipase expression of Candida albicans in vitro.

Materials and Methods:

Yeast cells isolated from clinical samples were suspended to a turbidity of 10⁶ in (a) Yeast extract-peptone-dextrose (YPD) broth and (b) culture filtrate, and 100 μl of each were dispensed in separate wells of microtiter plate. After repeated washing and reloading with respective liquid media, readings were taken spectrophotometrically. To check for lipase inhibition, yeasts were incubated overnight in YPD and filtrate and subcultured on media containing Tween-80 and CaCl₂. Positive lipase activity was denoted by haziness around colonies.

Results:

Mean reading of C. albicans in YPD broth was 0.579 while the same when yeasts were suspended in S. epidermidis culture filtrate was 0.281 (P < 0.05 by Z-test of significance). Lipase of C. albicans was inhibited by culture filtrate. Filtrate was found to be nontoxic to human cell line.

Conclusions:

Culture filtrate of S. epidermidis can hence pave the way for development of new strategies to inhibit biofilm formation in device-associated candidemia.

Amphotericin B lipid soluble formulations versus amphotericin B in cancer patients with neutropenia

BACKGROUND

Patients with cancer who are treated with chemotherapy or receive a bone marrow transplant have an increased risk of acquiring fungal infections. Such infections can be life-threatening. Antifungal drugs are therefore often given prophylactically to such patients, or when they have a fever.

OBJECTIVES

To compare the benefits and harms of lipid soluble formulations of amphotericin B with conventional amphotericin B in cancer patients with neutropenia.

SEARCH METHODS

We searched PubMed from 1966 to 7 July 2014 and the reference lists of identified articles.

SELECTION CRITERIA

Randomised clinical trials comparing lipid soluble formulations of amphotericin B with conventional amphotericin B.

DATA COLLECTION AND ANALYSIS

The two review authors independently assessed trial eligibility and risk of bias and abstracted data.

MAIN RESULTS

We found 13 trials (1960 patients). Lipid-based amphotericin B was not more effective than conventional amphotericin B on mortality (relative risk (RR) 0.5; 95% confidence interval (CI) 0.64 to 1.14) but decreased invasive fungal infection (RR 0.65; 95% CI 0.44 to 0.97), nephrotoxicity defined as a 100% increase in serum creatinine (RR 0.45; 95% CI 0.37 to 0.54), and number of dropouts (RR 0.78; 95% CI 0.62 to 0.97).For the drug used in most patients, AmBisome (4 trials, 1214 patients), there was no significant difference in mortality (RR 0.77; 95% CI 0.54 to 1.10) whereas it tended to be more effective than conventional amphotericin B on invasive fungal infection (RR 0.63; 95% CI 0.39 to 1.01, P value 0.053).AmBisome, amphotericin B in Intralipid (6 trials, 379 patients), amphotericin B colloidal dispersion (ABCD) (2 trials, 262 patients), and amphotericin B lipid complex (ABLC) (1 trial, 105 patients) all decreased the occurrence of nephrotoxicity, but conventional amphotericin B was rarely administered under optimal circumstances.

AUTHORS' CONCLUSIONS

It is not clear whether there are any advantages of lipid-based formulations if conventional amphotericin B is administered under optimal circumstances, and their high cost prohibits routine use in most settings. There is a need for large trials comparing lipid-based formulations of amphotericin B with conventional amphotericin B given in the same dose, with routine premedication for prevention of infusion-related toxicity, and with supplementation with fluid, potassium, and magnesium for prevention of nephrotoxicity.

Treatment of invasive candidiasis in the elderly: a review

Fungi are major causes of infections among immunocompromised or hospitalized patients with serious underlying diseases and comorbidities. Candida species remain the most important cause of opportunistic infections worldwide, affecting predominantly patients over 65 years old, while they are considered to be the fourth most common cause of nosocomial bloodstream infections. The rapidly growing elderly population has specific physiological characteristics, which makes it susceptible to colonization and subsequent infection due to Candida species. Comorbidities and multidrug use should be taken into account any time the therapeutic regimen is under consideration. Different classes of antifungal drugs are available for the treatment of invasive fungal infections but echinocandins, apart from their activity against resistant strains (Candida glabrata and Candida krusei), seem to be safe, with limited adverse events and minimal drug-drug interactions in comparison to the other regimens. Therefore, these agents are strongly recommended when dealing with elderly patients suffering from an invasive form of Candida infection.

Role of diuretics and lipid formulations in the prevention of amphotericin B-induced nephrotoxicity

PURPOSE

To collect available clinical data to define the role of diuretics and lipid formulations in the prevention of amphotericin B (AmB)-induced nephrotoxicity (AIN) in human populations.

METHOD

A literature search was performed in the following databases: Scopus, Medline, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews.

RESULTS AND CONCLUSION

Co-administration of mannitol failed to show any clinically significant benefit in preventing AIN. Potassium-sparing diuretics, such as amiloride and spironolactone, have been shown to have beneficial effects as an alternative or adjunct to oral/parenteral potassium supplements in preventing hypokalemia due to AmB. Lipid-based formulations of AmB are clinically effective and safe in preventing AIN. However, due to their high cost and limited accessibility, these formulations are generally used as second-line antifungal therapy in cases of conventional AmB refractoriness and/or intolerance or pre-existing renal dysfunction. The potential effects of other nephroprotective agents, such as N-acetylcysteine, AIN merit further considerations and investigations.

Use of antifungal drugs in hematology

Invasive fungal disease represents a major complication in hematological patients. Antifungal agents are frequently used in hematologic patients for different purposes. In neutropenic patients, antifungal agents may be used as prophylaxis, as empiric or preemptive therapy, or to treat an invasive fungal disease that has been diagnosed. The hematologist must be familiar with the epidemiology, diagnostic tools and strategies of antifungal use, as well as the pharmacologic proprieties of the different antifungal agents. In this paper the principal antifungal agents used in hematologic patients will be discussed as will the clinical scenarios where these agents have been used.

Systematic review and meta-analysis of the tolerability and hepatotoxicity of antifungals in empirical and definitive therapy for invasive fungal infection

To evaluate the tolerability and liver safety profiles of the systemic antifungal agents commonly used for the treatment of invasive fungal infection, we conducted a systematic review and meta-analysis of randomized controlled trials published before 31 August 2009. Two reviewers independently applied selection criteria, performed quality assessment, and extracted data. We used the beta-binomial model to account for variation across studies and the maximum likelihood method to estimate the pooled risks. We identified 39 studies with more than 8,000 enrolled patients for planned comparisons. The incidence rates of treatment discontinuation due to adverse reactions and liver injury associated with antifungal therapy ranged widely. The pooled risks of treatment discontinuation due to adverse reactions were above 10% for amphotericin B formulations and itraconazole, whereas they were 2.5% to 3.8% for fluconazole, caspofungin, and micafungin. We found that 1.5% of the patients stopped itraconazole treatment due to hepatotoxicity. Furthermore, 19.7% of voriconazole users and 17.4% of itraconazole users had elevated serum liver enzyme levels, although they did not require treatment discontinuation, whereas 2.0% or 9.3% of fluconazole and echinocandin users had elevated serum liver enzyme levels but did not require treatment discontinuation. The results were similar when we stratified the data by empirical or definitive antifungal therapy. Possible explanations for antifungal agent-related hepatotoxicity were confounded by antifungal prescription to patients with a high risk of liver injury, the increased chance of detection of hepatotoxicity due to prolonged treatment, or the pharmacological entity.

Reduction of amphotericin B-induced renal tubular apoptosis by N-acetylcysteine

The reduction of amphotericin B (AmB)-induced renal tubular apoptosis and nephrotoxicity by N-acetylcysteine (NAC) in a murine model was evaluated. Four groups of rats were treated with AmB for 5 days, and each group concomitantly received two doses of 30, 60, or 120 mg of NAC/kg of body weight/day or sterile water for 5 days. Groups that received concomitant NAC at any dose had significantly decreased levels of apoptosis compared to that in animals receiving AmB only (48.8% versus 27.4, 23.6, or 23.5%, respectively; P < 0.001).

Endocrine and metabolic manifestations of invasive fungal infections and systemic antifungal treatment

Systemic fungal infections are increasingly reported in immunocompromised patients with hematological malignancies, recipients of bone marrow and solid organ allografts, and patients with AIDS. Mycoses may infiltrate endocrine organs and adversely affect their function or produce metabolic complications, such as hypopituitarism, hyperthyroidism or hypothyroidism, pancreatitis, hypoadrenalism, hypogonadism, hypernatremia or hyponatremia, and hypercalcemia. Antifungal agents used for prophylaxis and/or treatment of mycoses also have adverse endocrine and metabolic effects, including hypoadrenalism, hypogonadism, hypoglycemia, dyslipidemia, hypernatremia, hypocalcemia, hyperphosphatemia, hyperkalemia or hypokalemia, and hypomagnesemia. Herein, we review how mycoses and conventional systemic antifungal treatment can affect the endocrine system and cause metabolic abnormalities. If clinicians are equipped with better knowledge of the endocrine and metabolic complications of fungal infections and antifungal therapy, they can more readily recognize them and favorably affect outcome.

Empirical antifungal therapy for patients with neutropenia and persistent fever: Systematic review and meta-analysis

OBJECTIVES

To assess the evidence for the current standard of practice of using empirical antifungal treatment in febrile neutropenic cancer patients.

METHODS

Systematic review and meta-analysis of randomised controlled trials comparing empirical or preemptive antifungal treatment with placebo, no intervention, or another antifungal. The primary outcomes were all-cause mortality and invasive fungal infections (IFI) (documented or probable). Relative risks (RR) with 95% confidence intervals (CI) were pooled.

RESULTS

Six trials assessed the efficacy of empirical treatment compared to no treatment and one compared empirical to preemptive therapy. Empirical treatment did not decrease mortality significantly (RR 0.82, 95% CI 0.50-1.34), but significantly decreased IFIs (RR 0.25, 0.12-0.54). Twenty-three trials assessed the efficiency of different antifungals. All-cause mortality was lower with azoles compared to amphotericin B (AB) (RR 0.81, 0.65-1.01); IFI rates were not different while adverse events were less frequent with azoles (RR 0.40; 0.34-0.66). Liposomal AB was associated with lower mortality and IFIs than other AB formulations (RR 1.57, 1.10-2.23 and 1.48, 0.98-2.25, respectively). Caspofungin was associated with fewer adverse events, but otherwise comparable to liposomal AB. All trials included patients with haematological malignancies. Major limitations included per-protocol analysis, non-blinded design and inconsistent definitions of IFIs.

CONCLUSIONS

Empirical antifungal treatment is associated with a lower rate of IFIs but no significant difference in overall mortality. The assessment of IFIs in these trials may have been biased, offering only weak support to standard practice. Azoles, liposomal amphotericin B or caspofungin should be preferred. Pre-emptive antifungal therapy should be considered and further investigated.

Safety of a pre-formulated amphotericin B lipid emulsion for the treatment of Indian Kala-azar

Amphotericin B (AB) deoxycholate is highly effective in antimony refractory cases for the treatment of visceral leishmaniasis (VL) in Bihar. But the need for prolonged hospitalisation and frequent, occasionally serious, adverse events are its major drawbacks. Lipid formulations of AB are devoid of these problems, but very expensive. We evaluated the safety and efficacy of a commercial standardised amphotericin B emulsion, a product of AB formulated in lipid emulsion vehicle (ABLE) in the treatment of Indian VL. In this open label, non-comparative study, 15 patients in each group were given three daily intravenous infusions each of 3, 4 or 5 mg/kg. All 45 patients (15 in each group) completed the treatment. The drug was tolerated well. Infusion reactions occurred in 5 (11%) patients and vomiting in 2 (4.4%). No nephrotoxicity or other organ toxicity was observed. At the end of treatment all patients of every group were clinically and parasitologically cured. However, during 6 months follow up, three patients from the 5 mg/kg group and one from the 4 mg/kg group tested positive for splenic aspirate. Thus 41 (91.1%; 95% CI 78-97) of 45 patients were cured with a total dose ranging between 9 and 15 mg/kg. There was no dose response linear correlation. In this preliminary study, AB formulated in a lipid emulsion vehicle was safe and effective for the treatment of VL in India.

Atualização no uso de agentes antifúngicos

Aborda-se sumariamente o espectro de ação, aspectos farmacológicos e toxicológicos e eficácia clínica de anfotericina B lipossomal, anfotericina B em dispersão coloidal, complexo lipídico de anfotericina B, voriconazol e caspofungina. Discute-se o uso desses antifúngicos mais recentes considerando a segurança, a eficiência e o custo da terapia. Sugestões para o uso clínico dessas drogas em infecções pulmonares e sistêmicas são apresentadas, destacando-se a menor toxicidade das formulações lipídicas da anfotericina B em relação à medicação convencional, a possibilidade de terapia primária da aspergilose invasiva, scedosporiose e fusariose com voriconazol e a caspofungina como opção terapêutica na candidíase disseminada e na aspergilose invasiva.

Fungal infection-related mortality versus total mortality as an outcome in trials of antifungal agents

BACKGROUND

Disease specific mortality is often used as outcome rather than total mortality in clinical trials. This approach assumes that the classification of cause of death is unbiased. We explored whether use of fungal infection-related mortality as outcome rather than total mortality leads to bias in trials of antifungal agents in cancer patients.

METHODS

As an estimate of bias we used relative risk of death in those patients the authors considered had not died from fungal infection. Our sample consisted of 69 trials included in four systematic reviews of prophylactic or empirical antifungal treatment in patients with cancer and neutropenia we have published previously.

RESULTS

Thirty trials met the inclusion criteria. The trials comprised 6130 patients and 869 deaths, 220 (25%) of which were ascribed to fungal infection. The relative risk of death was 0.85 (95% CI 0.75-0.96) for total mortality, 0.57 (95% CI 0.44-0.74) for fungal mortality, and 0.95 (95% CI 0.82-1.09) for mortality among those who did not die from fungal infection.

CONCLUSION

We could not support the hypothesis that use of disease specific mortality introduces bias in antifungal trials on cancer patients as our estimate of the relative risk for mortality in those who survived the fungal infection was not increased. We conclude that it seems to be reliable to use fungal mortality as the primary outcome in trials of antifungal agents. Data on total mortality should be reported as well, however, to guard against the possible introduction of harmful treatments.

New agents for the treatment of systemic fungal infections – current status

Systemic antifungal chemotherapy is enjoying its most dynamic era. More antifungal agents are under development than ever before, including agents in entirely new classes. Major goals of current investigations are to identify compounds with a wide spectrum of activity, minimal toxicity and a high degree of target specificity. The antifungal drugs in development include new azoles {voriconazole, posaconazole (formerly SCH-56592), ravuconazole (formerly BMS-207147)}, lipid formulations of amphotericin B, a lipid formulation of nystatin, echinocandins {anidulafungin (formerly, LY-303366, VER-002), caspofungin (formerly MK-991), micafungin (formerly FK-463)}, antifungal peptides other than echinocandins, and sordarin derivatives. This discussion reviews the currently available antifungal agents and summarises the developmental issues that surround these new systemic antifungal drugs.

Amphotericin B nephrotoxicity in children

Amphotericin B is the treatment of choice for severe systemic fungal infections. Nephrotoxicity is the most clinically significant adverse effect, but studies examining nephrotoxicity in children are scarce. Nephrotoxicity includes decreased glomerular filtration rate and distal tubulopathy with urinary loss of potassium and magnesium, renal tubular acidosis, loss of urine concentrating ability, and sometimes Fanconi's syndrome. The mechanisms involved in nephrotoxicity include the use of deoxycholate, the vehicle for amphotericin, reduction in renal blood flow and glomerular filtration rate, increased salt concentrations at the macula densa, interaction of amphotericin with ergosterol in the cell membrane, and apoptosis in proximal tubular cells and medullary interstitial cells. Some risk factors for amphotericin nephrotoxicity have been determined over the years. Cumulative dosage, treatment duration, and dosing schedule as well as the combination of amphotericin with other nephrotoxic drugs, such as diuretics and cyclosporine, are important risk factors. Mechanisms to prevent nephrotoxicity include the use of lipid formulations such as amphotericin B lipid complex, amphotericin B colloidal dispersion, and liposomal amphotericin B and the concurrent use of volume repletion. Amiloride can be considered in serious potassium loss.

SolEmuls-novel technology for the formulation of i.v. emulsions with poorly soluble drugs

Intravenously injectable o/w emulsions of drugs being poorly soluble in water and simultaneously in oils need to be produced by locating the drug in the interfacial lecithin layer, e.g. amphotericin B. For achieving this, up to now organic solvents were required. The objective was to develop a solvent-free production method for such emulsions. Drug and the pre-formed parenteral emulsion Lipofundin were mixed and subjected to high pressure homogenisation. Drug powder and emulsions were characterised regarding size and physical stability by photon correlation spectroscopy (PCS), laser diffractometry (LD) and zeta potential measurements. Drug incorporation was studied using light microscopy, electron microscopy (EM) and a centrifugation test to separate non-dissolved drug. Amphotericin B and carbamazepine were used as model drugs. The high streaming velocities lead to accelerated drug dissolution and partitioning into the interfacial layer (so-called "solubilisation by emulsification", SolEmuls Technology). The interfacial layer could incorporate (solubilise) a certain amount of drug, revealed by EM pictures. Exceeding this concentration, hybrid dispersions were formed consisting of drug-loaded oil droplets and drug nanocrystals of similar size (approximately 200 nm). Both dispersion types are i.v. injectable opening the opportunity to deliver the drug in a concentrated form at desired low injection volume, e.g. 10 mg/ml.

Antifungal therapy--state of the art at the beginning of the 21st century

The most relevant information on the present state of the art of antifungal chemotherapy is reviewed in this chapter. For dermatomycoses a variety of topical antifungals are available, and safe and efficacious systemic treatment, especially with the fungicidal drug terbinafine, is possible. The duration of treatment can be drastically reduced. Substantial progress in the armamentarium of drugs for invasive fungal infections has been made, and a new class of antifungals, echinocandins, is now in clinical use. The following drugs in oral and/or intravenous formulations are available: the broad spectrum polyene amphotericin B with its new "clothes"; the sterol biosynthesis inhibitors fluconazole, itraconazole, and voriconazole; the glucan synthase inhibitor caspofungin; and the combination partner flucytosine. New therapy schedules have been studied; combination therapy has found a significant place in the treatment of severely compromised patients, and the field of prevention and empiric therapy is fast moving. Guidelines exist nowadays for the treatment of various fungal diseases and maintenance therapy. New approaches interfering with host defenses or pathogenicity of fungal cells are being investigated, and molecular biologists are looking for new targets studying the genomics of pathogenic fungi.

Can we decrease amphotericin nephrotoxicity?

Amphotericin B (AmB) is considered the drug of choice for the treatment of systemic fungal infections. Nephrotoxicity is a major complication associated with its use, and appears to be related to higher cumulative doses, diuretic use, abnormal serum creatinine at baseline, and the use of concomitant nephrotoxic drugs. The two major hypotheses for the pathogenesis of AmB-related nephrotoxicity are direct effects of the drug on epithelial cell membranes and vasoconstriction. During the last few years, some randomized trials have tested different strategies to reduce AmB-induced renal toxicity. These strategies include sodium supplementation, low-dose dopamine, slower infusion rates, the administration of AmB in lipid emulsions, and in lipid formulations. The results of these trials showed that the lipid formulations of AmB significantly reduce nephrotoxicity. Unfortunately, these agents are costly, restricting their use to patients with a high risk of developing renal failure.

Renal transport of antibiotics and nephrotoxicity: a review

The renal excretion of a drug can essentially be divided schematically into three functional processes: glomerular filtration, tubular reabsorption and tubular secretion. When assessing nephrotoxicity, the tubular secretion system, which allows transport of the drug from the blood to the urine via the tubular cells, is particularly important. Historically, two distinct tubular secretion mechanisms have been described for drugs: one via organic cations and the other via organic anions. More recently, a third tubular secretion mechanism has been identified, mediated by P-glycoprotein. In the present review, a number of examples will be given relating to antibiotic-induced kidney damage determined via the tubular reabsorption mechanism (aminoglycosides, amphotericin B) and via the tubular secretion mechanism (cephalosporins, vancomycin), respectively. Drug transport within the tubular cells is the first fundamental stage in the onset of the nephrotoxic process. Knowledge of these concepts is important for the prevention of iatrogenic kidney damage, particularly in patients with underlying disease receiving concomitant treatment with several potentially nephrotoxic molecules.

[New lipid formulations of amphotericin B. Review of the literature]

INTRODUCTION

Amphotericin B (amB) remains the gold standard for treatment of invasive fungal infections. Lipid formulations of amB have been developed in an attempt to improve both efficacy and tolerability (especially renal toxicity): amB lipid complex (ABLC), liposomal amB (AmBisome), amB colloidal dispersion (ABCD) and amB in lipid emulsion (Intralipid). This review analyzes the data available in the literature.

CURRENT KNOWLEDGE AND KEY POINTS

ABLC, AmBisome and ABCD are effective in various fungal infections, including invasive aspergillosis, systemic candidiasis, cryptococcal meningitis, mucormycosis and fusariosis. These formulations are also effective in persistent febrile neutropenia and in leishmaniosis. The three formulations show little renal toxicity and are safer than conventional amB in this respect. Preliminary data are available on amB in Intralipid: infusion-related adverse effects are reduced, but few data are available on efficacy in documented mycoses.

FUTURE PROSPECTS AND PROJECTS

Large-scale comparative clinical trials may clarify issues of relative efficacy in various forms of fungal infections.

Amphotericin B-induced nephrotoxicity: a review

Amphotericin B is the gold standard for antifungal treatment for the most severe mycoses. However, adverse effects are common, with nephrotoxicity being the most serious, occurring early in the course of treatment, and usually being reversible in most patients. Tubular damage is a well known problem associated with amphotericin B therapy but acute renal failure is the most serious complication. Recent studies have examined ways to ameliorate the well-known toxicities of amphotericin B. A new approach has been to complex the drug with lipids or entrap it in liposomes. This review will concern amphotericin B-induced nephrotoxicity, whose mechanisms are not completely clear. Nephrotoxicity seems related to direct amphotericin B action on the renal tubules as well as to drug-induced renal vasoconstriction. The main mechanisms of nephrotoxicity suggested in the literature are presented. The clinical picture at different ages (adults, children, newborns), interactions of clinical significance, strategies for prevention of amphotericin B-induced nephrotoxicity are summarized. To provide optimal patient care, it is imperative that the clinician understand the etiology of and the signs and symptoms associated with nephrotoxicity, as well as interventions to prevent nephrotoxicity in patients receiving amphotericin B.

Amphotericin B lipid soluble formulations vs amphotericin B in cancer patients with neutropenia

BACKGROUND

Patients with cancer who are treated with chemotherapy or receive a bone marrow transplant have an increased risk of acquiring fungal infections. Such infections can be life-threatening. Antifungal drugs are therefore often given prophylactically to such patients, or when they have a fever.

OBJECTIVES

To compare the effect and adverse effects of AmBisome and other lipid soluble formulations of amphotericin B with conventional amphotericin B in cancer patients with neutropenia.

SEARCH STRATEGY

MEDLINE and Cochrane Library. Unpublished trials from conference proceedings and contact to industry.

SELECTION CRITERIA

Randomised trials comparing lipid soluble formulations of amphotericin B with conventional amphotericin B.

DATA COLLECTION AND ANALYSIS

Data on mortality, invasive fungal infection, nephrotoxicity, serum creatinine and dropouts were extracted by both authors independently.

MAIN RESULTS

AmBisome vs conventional amphotericin B (3 trials, 1149 patients): AmBisome tended to be more effective than conventional amphotericin B for invasive fungal infection (relative risk 0.63, 95% confidence interval 0.39 to 1.01, P=0.053) whereas there was no significant difference in mortality (relative risk 0.74, 95% CI 0.52 to 1.07). AmBisome decreased significantly the incidence of nephrotoxicity, defined as a 100% increase in serum creatinine (relative risk 0.51, 95% CI 0.40 to 0.64). Fewer patients dropped out on AmBisome but the difference was not significant (relative risk 0.78, 95% CI 0.56 to 1. 08). Amphotericin B in Intralipid vs conventional amphotericin B (4 trials, 145 patients): There were no significant differences in clinical effect whereas the patients treated with the lipid soluble formulation experienced significantly less nephrotoxicity (relative risk 0.34, 95% CI 0.15 to 0.75) and smaller increases in serum creatinine (weighted mean difference 32 micromol/l, 95% CI 21 to 43 micromol/l). Amphotericin B colloidal dispersion (ABCD) vs conventional amphotericin B (1 trial, 213 patients): There was lower nephrotoxicity with ABCD (relative risk 0.38, 95% CI 0.25 to 0.59).

REVIEWER'S CONCLUSIONS

AmBisome is a better drug than conventional amphotericin B but its high cost prohibits routine use in most settings. Furthermore, the advantages of AmBisome may be smaller than indicated in our review if conventional amphotericin B is administered under optimal circumstances. It is not clear whether other lipid formulations of amphotericin B could offer a worthwhile advantage compared to conventional amphotericin B.