A comparative analysis of lipid-complexed and liposomal amphotericin B preparations in haematological oncology

Amphotericin B in the Era of New Antifungals: Where Will It Stand?

Amphotericin B (AmB) has long stood as a cornerstone in the treatment of invasive fungal infections (IFIs), especially among immunocompromised patients. However, the landscape of antifungal therapy is evolving. New antifungal agents, boasting novel mechanisms of action and better safety profiles, are entering the scene, presenting alternatives to AmB's traditional dominance. This shift, prompted by an increase in the incidence of IFIs, the growing demographic of immunocompromised individuals, and changing patterns of fungal resistance, underscores the continuous need for effective treatments. Despite these challenges, AmB's broad efficacy and low resistance rates maintain its essential status in antifungal therapy. Innovations in AmB formulations, such as lipid complexes and liposomal delivery systems, have significantly mitigated its notorious nephrotoxicity and infusion-related reactions, thereby enhancing its clinical utility. Moreover, AmB's efficacy in treating severe and rare fungal infections and its pivotal role as prophylaxis in high-risk settings highlight its value and ongoing relevance. This review examines AmB's standing amidst the ever-changing antifungal landscape, focusing on its enduring significance in current clinical practice and exploring its potential future therapeutic adaptations.

Retrospective Analysis on the Use of Amphotericin B Lipid Complex in Neutropenic Cancer Patients with Suspected Fungal Infections in Lebanon, a Single Center Experience and Review of International Guidelines

INTRODUCTION

Immunocompromised patients carry a high risk for invasive fungal disease (IFD), which is associated with high mortality.

MATERIALS AND METHODS

This is a retrospective chart review of a 4-year experience of amphotericin B lipid complex (ABLC) utilization for the management of suspected IFD at the Hematology/Oncology and Bone Marrow Transplantation unit at Makassed General Hospital, Beirut, Lebanon between January 2011 and December 2014. We focused on treatment strategy, response rate, and adverse drug events associated with ABLC therapy. We also reviewed ABLC indications in international guidelines beyond its Food and Drug Administration approval.

RESULTS

A total of 89 patients received ABLC therapy for suspected fungal infection. Forty-eight percent were treated for a possible fungal infection, 19% for a problable fungal infection, 12% based on hospital guidelines, and 20% based on treating physician's recommendations. The overall response rate was 71%. Nephrotoxicity occurred in 24% of patients and serum creatinine improved in 10% of these patients. Moderate hypokalemia was observed in 61% of the patients and severe hypokalemia in 10% but was corrected in both cases. Hepatotoxicity was observed in 12% of the patients throughout ABLC therapy. Infusion-related reactions were observed in 36% of the patients. There was a decrease in the incidence of these reactions upon using combination of premedication drugs.

CONCLUSION

In this study, ABLC proved to be an effective and safe option in the management of suspected IFD in immunocompromised patients failing previous therapies.

Budget impact analysis of liposomal amphotericin B and amphotericin B lipid complex in the treatment of invasive fungal infections in the United States

BACKGROUND

Liposomal amphotericin B (L-AMB) and amphotericin B lipid complex (ABLC) are both indicated for treating invasive fungal infections (IFIs) caused by Aspergillus, Candida and Cryptococcus spp. among patients who are refractory to or intolerant of conventional amphotericin B (CAB). Prior studies have suggested similar efficacies but differences in adverse event (AE) profiles between L-AMB and ABLC.

OBJECTIVE

Our objective was to conduct a cost-minimisation and budget impact analysis for the treatment of IFIs with L-AMB and ABLC in a US hospital setting.

METHODS

A Microsoft® Excel-based budget impact model was developed to estimate the costs associated with using L-AMB and ABLC for the treatment of adult patients with Aspergillus, Candida and Cryptococcus spp. infections, who are refractory to or intolerant of CAB, during a hospital stay. The model was built from a hospital perspective, and included drug costs of L-AMB and ABLC, and costs for treating drug-related AEs (i.e. nephrotoxicity with/without dialysis, infusion-related reactions, anaphylaxis, hypomagnesaemia and hypokalaemia). Average sales price was used as the drug cost estimate in the base-case analyses. The treatment duration and rates of AEs for L-AMB and ABLC were mainly obtained from a retrospective study of these two drugs in the target population using the Cerner Health Facts data. Treatment costs of AEs were obtained from the publicly available sources. The budget impact ($US, year 2011 values) was evaluated for a hypothetical hospital with 100 administrations where L-AMB and ABLC are used for the treatment of the target population by changing the market share of L-AMB and ABLC from 32/68% to an anticipated market share of 60/40% in the base-case analysis. Sensitivity analyses were conducted by varying drug costs, rates of AEs, costs of AEs and anticipated market shares of L-AMB and ABLC.

RESULTS

The estimated per-patient cost per hospital episode associated with L-AMB and ABLC use were $US14,563 and $US16,748, respectively. Cost of AEs accounted for 68.7% of the costs for L-AMB and 85.4% for ABLC. In a hypothetical hospital with 100 annual admissions of patients using these two drugs for IFIs, changing the market shares from 32/68% for L-AMB and ABLC, respectively, to 60/40% yielded a 3.8% cost reduction, which corresponded to an absolute cost savings of $US61,191. Sensitivity analyses indicated that the results were robust to changes in input parameter values in most cases.

CONCLUSIONS

This study suggests that hospitals can realize cost savings by substituting L-AMB for ABLC in the treatment of IFIs. The cost savings are driven by the lower rates of AEs associated with L-AMB use compared with ABLC.

Nephrotoxicity and other adverse events among inpatients receiving liposomal amphotericin B or amphotericin B lipid complex

Nephrotoxicity evaluations between liposomal amphotericin B (L-AMB) and amphotericin B lipid complex (ABLC) have provided mixed results. This retrospective study used an electronic medical record database of hospitalized patients with invasive fungal infections treated with either L-AMB or ABLC. Patients had renal insufficiency, clinical condition suggesting intolerance to amphotericin B deoxycholate (CAB), or recent CAB exposure. Baseline SCr, exposure to other nephrotoxic agents, and total amphotericin B exposure were similar between the groups. In 105 patients administered L-AMB, 10.6% had nephrotoxicity versus 22.6% of 222 patients administered ABLC (P = 0.020). A logistic regression model found ABLC patients had 3.48 higher odds (95% CI 1.05-11.52) than L-AMB of developing nephrotoxicity. Infusion reactions were more prevalent with ABLC (23.9% versus 9.5%, P = 0.002) as was hypomagnesemia (44.3% versus 28.1%, P = 0.033). This study demonstrated that L-AMB is associated with less nephrotoxicity, infusion reactions and hypomagnesemia than ABLC in patients at increased risk of nephrotoxicity.

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.

The current role of amphotericin B lipid complex in managing systemic fungal infections

BACKGROUND

An increase in the number of immunocompromised patients has led to a rising burden of systemic fungal infections. Historically, conventional amphotericin B has been used to treat these infections due to its broad spectrum of activity. The development of lipid-based amphotericin B agents, such as Abelcet * (ABLC), has allowed clinicians to take advantage of the broad spectrum of activity of amphotericin B while reducing adverse events. As well as this, a number of new antifungal agents have been developed in recent years which have significantly added to the treating physician's antifungal armamentarium. * Abelcet is a registered trade name of Cephalon Ltd, Herts, UK.

OBJECTIVES

Review the clinical data that support the use of ABLC and discuss the evidence for its continuing role in the treatment of invasive fungal infections in light of the introduction of newer antifungal agents.

METHODS

Published studies were identified by searching the MEDLINE database and the Cochrane Centre for Reviews up to August 2009. The search was conducted using the following key words: Amphotericin, Lipid, Abelcet, AmBisome, Efficacy, Nephrotoxicity, Renal, Toxicity.

FINDINGS

ABLC is effective and well-tolerated in the treatment of systemic fungal infections and remains a valuable therapeutic option in a variety of immunocompromised patients due to its broad antifungal spectrum and rarity of resistance.

LIMITATIONS

Data from randomised controlled trials of lipid-based amphotericin B formulations, as well as head-to-head comparison studies between ABLC and other antifungal agents are limited. In addition, the review uses a narrative approach and relies to a great extent on the authors' personal views and experiences.

A safety and feasibility study comparing an intermittent high dose with a daily standard dose of liposomal amphotericin B for persistent neutropenic fever

A high intermittent dose regimen (group A: 10 mg kg(-1) on day 1, 5 mg kg(-1) on days 3 and 6) was compared with standard dosing (group B: 3 mg kg(-1) per day for 14 days) of liposomal amphotericin B (LAB) for empirical treatment of persistent febrile neutropenia. A total cumulative dose of 1275 mg (group A) and 2800 mg (group B) was administered. Infusion-related adverse drug events, mainly rigors/chills, occurred more frequently with group A (11/45, 24 % infusions) than with group B (12/201, 6 % infusions) (P=0.002), which extended the mean infusion time by 20 min (P=0.001). Creatinine levels were similar in the two regimens: the A : B ratio of the area under the curve for creatinine (AUC(CREATININE)) for days 2-7 was 1.09 (P=0.27) and for days 2-14 was 1.05 (P=0.51). Rises in creatinine were mild (clinical toxicity criteria 1) in all patients with elevations. Hypokalaemia tended to be less severe in group A with a lower proportion of hypokalaemic days [57/143 (39 %) vs 80/137 (58 %), P=0.21], a higher AUC(POTASSIUM) (A : B ratio of 1.06, P=0.12), a lower proportion of patients with hypokalaemia at the end of study (10 vs 61 %, P=0.01) and fewer potassium-supplemented days [12/210 (6 %) vs 41/210 (19.5 %), P<0.1]. There were mildly elevated median levels of serum bilirubin, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase, which were similar for the two regimens and were usually associated with other co-existing co-morbid conditions. The AUC for these enzymes was also similar in the two groups. No patient had discontinuation of the study drug due to toxicity. Composite success was identical for each regimen (11/15 patients, 73 %). Three of the fifteen patients in group B and none in group A developed invasive fungal infections (IFIs). Beta-D-Glucan levels were similar in both groups for patients without an IFI [AUC(GLUCAN) of 362 and 683 (P=0.36) for groups A and B, respectively]. The rate of defervescence was similar for each regimen (P=0.75). This feasibility study suggests that a short intermittent high-dose course of 10/5/5 mg LAB kg(-1) on days 1, 3 and 6 may be as safe and effective as a standard 14 day course of 3 mg kg(-1) per day, with drug-acquisition cost savings and reduced drug exposure. A larger study is indicated for confirmation of this.

Economic evaluation of caspofungin versus liposomal amphotericin B for empiric antifungal treatment in patients with neutropenic fever in Italy

OBJECTIVE

To evaluate the cost-effectiveness of caspofungin versus liposomal amphotericin B as empiric antifungal treatment in patients with neutropenic fever in Italy.

METHODS

The cost-effectiveness of caspofungin versus liposomal amphotericin B was evaluated using a decision-tree model. Patients were stratified by presence or absence of baseline infection. Model outcomes included success in terms of resolution of fever, resolution of baseline infection, absence of breakthrough infection, survival, and quality-adjusted life years (QALYs) saved. Discontinuation because of nephrotoxicity or other adverse events were included in the model. Efficacy and safety data were based on a randomized, double-blind, multinational trial of caspofungin compared to liposomal amphotericin B (Walsh 2004). Information on life expectancy, quality of life, medical resource consumption, and costs was obtained from the literature.

RESULTS

The caspofungin estimated total treatment cost amounted to 8351 euros (95% uncertainty interval 7801 euros-8903 euros), which is 3470 euros (2575 euros-4382 euros) less than with liposomal amphotericin B. Treatment with caspofungin resulted in 0.25 (-0.11; 0.59) QALYs saved in comparison to treatment with liposomal amphotericin B. Probabilistic sensitivity analysis demonstrated a 93% probability that caspofungin was economically dominant, i.e., cost and QALY saving, and a probability of more than 99% that the costs per QALY saved were below 20,000 euros, a commonly accepted threshold for cost-effectiveness. Additional analyses with alternative doses of liposomal amphotericin B confirmed these findings.

CONCLUSION

Given the underlying assumptions, our economic evaluation demonstrated that caspofungin is cost-effective compared to liposomal amphotericin B in empiric antifungal treatment of patients with neutropenic fever in Italy.

Nephrotoxicity in the setting of invasive fungal diseases

Amphotericin B, a broad spectrum antifungal agent, is widely used despite significant adverse events including nephrotoxicity. Nephrotoxicity occurs frequently in patients receiving amphotericin B. Different definitions for nephrotoxicity are reviewed in the context of outcome in patients with invasive fungal diseases. In most publications, mortality was higher in patients experiencing nephrotoxicity and mean hospital length of stay was prolonged. As a consequence, the use of less nephrotoxic antifungal agents could improve treatment outcomes.

Prospective Study of Amphotericin B Formulations in Immunocompromised Patients in 4 European Countries

BACKGROUND

Amphotericin B is a widely used broad-spectrum antifungal agent, despite being associated with significant adverse events, including nephrotoxicity.

METHODS

The present prospective study collected data on outcomes for 418 adult patients treated consecutively with polyenes in hematology and oncology wards in 20 hospitals in Europe.

RESULTS

Patients initially received amphotericin B deoxycholate (62% of patients), liposomal amphotericin B (27%), or other lipid formulations of amphotericin B (11%). Of the patients initially treated with amphotericin B deoxycholate, 36% had therapy switched to lipid formulations of amphotericin B, primarily because of increased serum creatinine levels (in 45.7% of patients) or other amphotericin B-attributable adverse events (in 41.3% of patients). Nephrotoxicity, which was defined as a > or = 50% increase in the serum creatinine level, developed in 57% of patients with normal kidney function at baseline. Predictors of nephrotoxicity included formulation type and duration of treatment. Compared with patients without nephrotoxicity, patients with nephrotoxicity had a higher mortality rate (24%), and their mean length of stay in the hospital was prolonged by 8.6 days. Slight increases in the serum creatinine level (i.e., > or = 50%) were associated with a significantly longer stay in the hospital. Severe nephrotoxicity (i.e., a > or = 200% increase in the serum creatinine level) was a significant predictor of death, as were severe underlying medical conditions and documented fungal infection.

CONCLUSION

This prospective study confirmed that, in European hospitals, amphotericin B formulations have a major influence on the length of stay in the hospital and nephrotoxicity-associated mortality.

Adverse effects of antifungal therapies in invasive fungal infections: review and meta-analysis

Amphotericin B is the main therapeutic agent for the treatment of invasive fungal infections; however, it is associated with significant toxicities that limit its use. Other systemic antifungal agents have been developed to improve tolerability while maintaining the efficacy profile of conventional amphotericin B. Fifty-four studies involving 9,228 patients were assessed for the frequency of adverse effects of the main systemic antifungal agents. While the results suggest that liposomal amphotericin B is the least nephrotoxic of the lipid formulations (14.6%), that conventional amphotericin B is the most nephrotoxic (33.2%), and that itraconazole is the most hepatotoxic (31.5%), the lack of standard definitions of antifungal-related adverse effects limits the validity of these results. Furthermore, heterogeneous patient pools and differing protocols make it difficult to draw direct comparisons between studies. With the advent of newer classes of systemic antifungal agents, future trials should conform to definitions that are universally applicable and clinically relevant to allow for such comparisons and to enable evidence-based decision-making.

Adverse effects of antifungal therapies in invasive fungal infections: review and meta-analysis

Amphotericin B is the main therapeutic agent for the treatment of invasive fungal infections; however, it is associated with significant toxicities that limit its use. Other systemic antifungal agents have been developed to improve tolerability while maintaining the efficacy profile of conventional amphotericin B. Fifty-four studies involving 9,228 patients were assessed for the frequency of adverse effects of the main systemic antifungal agents. While the results suggest that liposomal amphotericin B (L-AmB) is the least nephrotoxic of the lipid formulations (14.6%), that conventional amphotericin B (AmB) is the most nephrotoxic (33.2%), and that itraconazole is the most hepatotoxic (31.5%), the lack of standard definitions of antifungal-related adverse effects limits the validity of these results. Furthermore, heterogeneous patient pools and differing protocols make it difficult to draw direct comparisons between studies. With the advent of newer classes of systemic antifungal agents, future trials should conform to definitions that are universally applicable and clinically relevant to allow for such comparisons and to enable evidence-based decision-making.

Antimicrobial therapy for patients with severe sepsis and septic shock: an evidence-based review

OBJECTIVE

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for antimicrobial therapy for patients with severe sepsis and septic shock that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee.

METHODS

The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591.

CONCLUSION

Since the prompt institution of therapy that is active against the causative pathogen is one of the most important predictors of outcome, clinicians must establish a system for rapid administration of a rationally chosen drug or combination of drugs when sepsis or septic shock is suspected. The expanding number of antibacterial, antifungal, and antiviral agents available provides opportunities for effective empiric and specific therapy. However, to minimize the promotion of antimicrobial resistance and cost and to maximize efficacy, detailed knowledge of the likely pathogens and the properties of the available drugs is necessary for the intensivist.

Guidelines for the use of antifungal agents in the treatment of invasiveCandidaand mould infections

ABSTRACT Treatment of invasive fungal infections is increasingly complex. Amphotericin B deoxycholate has long been the mainstay of treatment. However, there has been increasing recognition of both the propensity for nephro-toxicity in haematology, transplant and intensive care patients as well as its adverse impact on morbidity and mortality. This has coincided with the availabilty of newer, and in certain settings, more effective antifungal agents. Although the newer agents clearly cause less nephrotoxicity than amphotericin B, drug interactions, hepatic effects and unique side-effects need to be considered. The spectrum of the newer triazoles and echinocandins varies, highlighting the importance of accurate identification of the causative organism where possible. Consensus Australian guidelines have been developed to assist clinicians with treatment choices by reviewing the current evidence for the efficacy, the toxicity and the cost of these agents.

Pharmacoeconomic analysis of amphotericin B lipid complex versus liposomal amphotericin B in the treatment of fungal infections

BACKGROUND

Potential differences in toxicity, potency and acquisition price among the liposomal amphotericin B formulations makes it unclear which agent is less costly when total resource consumption and treatment-associated costs are considered.

DESIGN

A retrospective cost-minimisation analysis in 51 patients was performed to compare the cost of amphotericin B lipid complex (ABLC) and liposomal amphotericin B (L-AMB) from the hospital perspective. Costs ($US, 2001 values) were divided into level I (acquisition price only), level II (costs of all associated treatment, i.e. adverse events, failures, etc.) and level III (total fungal-related hospitalisation) costs.

RESULTS

No significant differences in patient demographics or length of therapy were apparent among those receiving ABLC or L-AMB. The clinical success rate in this population was similar between ABLC and L-AMB (53% vs 60%, p = 0.68), thus justifying the use of a cost-minimisation analysis. Among patients with baseline elevations in serum creatinine, 47% receiving ABLC and 10% receiving L-AMB experienced further increases in serum creatinine (p = 0.025). No differences in total treatment costs (level I, II, or III) were evident between patients receiving ABLC or L-AMB. When adjusted for duration of therapy, however, costs were significantly lower for ABLC than for L-AMB (level I: ABLC $US340 versus L-AMB $US435, p = 0.002; level II: ABLC $US361 versus L-AMB $US454, p = 0.027). The costs attributable to the prevention or treatment of adverse events were not different between the two treatments, and the economic outcome in this analysis was highly sensitive to the acquisition price and dosage of the lipid antifungal formulation. Two-way sensitivity analysis revealed that as long as the milligram price of L-AMB was greater than 135% of the milligram price of ABLC, ABLC remained the less costly formulation.

CONCLUSION

In this patient population, total hospitalisation costs were not different between lipid antifungal formulations. However, after controlling for duration of therapy, ABLC was less costly than L-AMB, when considering acquisition costs of the lipid antifungal agent and costs associated with concomitant antifungal therapy and the treatment of adverse events or lipid failures, indicating that the acquisition price of these agents should be predictive of their cost differences.

Amphotericin B: time for a new "gold standard"

When introduced in 1959, amphotericin B deoxycholate (AmBD) was clearly a life-saving drug. Randomized studies demonstrating its efficacy were not thought to be necessary, and it was granted indications for many invasive fungal infections. Despite its formidable toxicities, AmBD is thus often used as the primary comparator in studies of invasive fungal infections. Safer lipid-based versions of amphotericin B (AmB) have been introduced, but difficulties with studying these agents generally led to licensure for salvage therapy, not primary therapy. However, the cumulative clinical experience to date with the lipid-based preparations is now adequate to demonstrate that these agents are no less active than AmBD, and, for some infections, it can now be stated that specific lipid-based preparations of AmB are superior to AmBD. Given their superior safety profiles, these preparations can now be considered suitable replacements for AmBD for primary therapy for many invasive fungal infections in clinical practice and research.

Commonly used antibacterial and antifungal agents for hospitalised paediatric patients: implications for therapy with an emphasis on clinical pharmacokinetics

Due to normal growth and development, hospitalised paediatric patients with infection require unique consideration of immune function and drug disposition. Specifically, antibacterial and antifungal pharmacokinetics are influenced by volume of distribution, drug binding and elimination, which are a reflection of changing extracellular fluid volume, quantity and quality of plasma proteins, and renal and hepatic function. However, there is a paucity of data in paediatric patients addressing these issues and many empiric treatment practices are based on adult data. The penicillins and cephalosporins continue to be a mainstay of therapy because of their broad spectrum of activity, clinical efficacy and favourable tolerability profile. These antibacterials rapidly reach peak serum concentrations and readily diffuse into body tissues. Good penetration into the cerebrospinal fluid (CSF) has made the third-generation cephalosporins the agents of choice for the treatment of bacterial meningitis. These drugs are excreted primarily by the kidney. The carbapenems are broad-spectrum beta-lactam antibacterials which can potentially replace combination regimens. Vancomycin is a glycopeptide antibacterial with gram-positive activity useful for the treatment of resistant infections, or for those patients allergic to penicillins and cephalosporins. Volume of distribution is affected by age, gender, and bodyweight. It diffuses well across serous membranes and inflamed meninges. Vancomycin is excreted by the kidneys and is not removed by dialysis. The aminoglycosides continue to serve a useful role in the treatment of gram-negative, enterococcal and mycobacterial infections. Their volume of distribution approximates extracellular space. These drugs are also excreted renally and are removed by haemodialysis. Passage across the blood-brain barrier is poor, even in the face of meningeal inflammation. Low pH found in abscess conditions impairs function. Toxicity needs to be considered. Macrolide antibacterials are frequently used in the treatment of respiratory infections. Parenteral erythromycin can cause phlebitis, which limits its use. Parenteral azithromycin is better tolerated but paediatric pharmacokinetic data are lacking. Clindamycin is frequently used when anaerobic infections are suspected. Good oral absorption makes it a good choice for step-down therapy in intra-abdominal and skeletal infections. The use of quinolones in paediatrics has been restricted and most information available is in cystic fibrosis patients. High oral bioavailability is also important for step-down therapy. Amphotericin B has been the cornerstone of antifungal treatment in hospitalised patients. Its metabolism is poorly understood. The half-life increases with time and can be as long as 15 days after prolonged therapy. Oral absorption is poor. The azole antifungals are being used increasingly. Fluconazole is well tolerated, with high bioavailability and good penetration into the CSF. Itraconazole has greater activity against aspergillus, blastomycosis, histoplasmosis and sporotrichosis, although it's pharmacological and toxicity profiles are not as favourable.

A prospective and retrospective analysis of the nephrotoxicity and efficacy of lipid-based amphotericin B formulations

STUDY OBJECTIVE

To determine the usage patterns of the lipid-based amphotericin B formulations at our institution and to compare the observed nephrotoxicity and efficacy of these formulations.

DESIGN

Prospective and retrospective observational study

SETTING

Urban 350-bed teaching hospital.

PATIENTS

Sixty-seven nonhemodialysis patients who were prescribed greater than 3 days of amphotericin B lipid complex (ABLC) or liposomal amphotericin B (L-AmB) from 1996-1999.

MEASUREMENTS AND RESULTS

Forty-six patients received ABLC and 21 received L-AmB. Oncology patients accounted for most prescriptions of both formulations. Amphotericin B lipid complex most frequently was prescribed for treatment of documented fungal infections (50%), followed by treatment of neutropenic fever (33%). Liposomal amphotericin B most frequently was prescribed for treatment of neutropenic fever (62%), followed by treatment of documented fungal infections (29%). Seventy-eight percent of patients treated with ABLC and 90% of those who received L-AmB were started on the lipid-based formulation due to being refractory or intolerant to prior antifungal therapy. Two (4.4%) patients receiving ABLC and four (19%) patients receiving L-AmB experienced nephrotoxicity at the end of therapy (NS). Of the patients with a documented fungal infection, 20 out of 23 (87%) of those treated with ABLC and 4 out of 5 (80%) of those treated with L-AmB had a complete or partial response to therapy (NS). One patient with febrile neutropenia had a breakthrough fungal infection while receiving L-AmB.

CONCLUSION

No significant differences in nephrotoxicity or efficacy were found between ABLC and L-AmB. Until further studies indicate clinically significant differences in nephrotoxicity between the two liposomal amphotericin B formulations, it is recommended that economics continue to be the major determinant for product selection.

Current management of fungal infections

The management of superficial fungal infections differs significantly from the management of systemic fungal infections. Most superficial infections are treated with topical antifungal agents, the choice of agent being determined by the site and extent of the infection and by the causative organism, which is usually readily identifiable. One exception is onychomycosis, which usually requires treatment with systemically available antifungals; the accumulation of terbinafine and itraconazole in keratinous tissues makes them ideal agents for the treatment of onychomycosis. Oral candidiasis in immunocompromised patients also requires systemic treatment; oral fluconazole and itraconazole oral solution are highly effective in this setting. Systemic fungal infections are difficult to diagnose and are usually managed with prophylaxis or empirical therapy. Fluconazole and itraconazole are widely used in chemoprophylaxis because of their favourable oral bioavailability and safety profiles. In empirical therapy, lipid-associated formulations of amphotericin-B and intravenous itraconazole are safer than, and at least as effective as, conventional amphotericin-B (the former gold standard). The high acquisition costs of the lipid-associated formulations of amphotericin-B have limited their use.

Amphotericin B--not so terrible

OBJECTIVE

To describe a patient who developed adverse reactions to two different lipid formulations of amphotericin B: liposomal amphotericin B (AmBisome) and amphotericin B colloidal dispersion (ABCD, Amphocil), yet tolerated amphotericin B deoxycholate (Fungizone) despite renal toxicity.

CASE SUMMARY

A 72-year-old woman with acute myelomonocytic leukemia was treated with amphotericin B deoxycholate for suspected pulmonary aspergillosis; the drug was well tolerated but resulted in renal failure. Antifungal therapy was then changed to liposomal amphotericin B. Within 10 minutes of liposomal amphotericin B infusion, the patient developed severe dyspnea, chest pain, and a feeling of imminent death. On the following day, liposomal amphotericin B was switched to amphotericin B colloidal dispersion. Again, within 10 minutes of this infusion, the patient developed fever, chills, hypotension, severe chest pain, dsypnea, and a feeling of imminent death. The patient refused any further treatment with these drugs and insisted on switching back to amphotericin B deoxycholate, which was then administered for 10 days and was well tolerated.

DISCUSSION

Severe adverse reactions, such as anaphylaxis, cardiac toxicity, and respiratory failure, following administration of all three lipid formulations of amphotericin B have been reported. In most reported cases, switching to a different lipid formulation of amphotericin B was well tolerated. This is in contrast to our case, where a severe reaction was repeated when another lipid preparation was given, necessitating switching back to amphotericin B deoxycholate despite its nephrotoxicity.

CONCLUSIONS

In some patients, paradoxically, lipid formulations of amphotericin B may be less tolerable than conventional amphotericin B.

A randomized, double-blind comparative trial evaluating the safety of liposomal amphotericin B versus amphotericin B lipid complex in the empirical treatment of febrile neutropenia. L Amph/ABLC Collaborative Study Group

In this double-blind study to compare safety of 2 lipid formulations of amphotericin B, neutropenic patients with unresolved fever after 3 days of antibacterial therapy were randomized (1:1:1) to receive amphotericin B lipid complex (ABLC) at a dose of 5 mg/kg/d (n=78), liposomal amphotericin B (L Amph) at a dose of 3 mg/kg/d (n=85), or L Amph at a dose of 5 mg/kg/d (n=81). L Amph (3 mg/kg/d and 5 mg/kg/d) had lower rates of fever (23.5% and 19.8% vs. 57.7% on day 1; P<.001), chills/rigors (18.8% and 23.5% vs. 79.5% on day 1; P<.001), nephrotoxicity (14.1% and 14.8% vs. 42.3%; P<.01), and toxicity-related discontinuations of therapy (12.9% and 12.3% vs. 32.1%; P=.004). After day 1, infusional reactions were less frequent with ABLC, but chills/rigors were still higher (21.0% and 24.3% vs. 50.7%; P<.001). Therapeutic success was similar in all 3 groups.