Retrospective analysis of the dosage of amphotericin B lipid complex for the treatment of invasive fungal infections

Emerging drugs and vaccines for candidemia

Candidemia and other forms of invasive candidiasis are important causes of morbidity and mortality. The evolving challenge of antimicrobial resistance among fungal pathogens continues to highlight the need for potent, new antifungal agents. MEDLINE, EMBASE, Scopus and Web of Science searches (up to January 2014) of the English-language literature were performed with the keywords 'Candida' or 'Candidemia' or 'Candidiasis' and terms describing investigational drugs with activity against Candida spp. Conference abstracts and the bibliographies of pertinent articles were also reviewed for relevant reports. ClinicalTrials.gov was searched for relevant clinical trials. Currently available antifungal agents for the treatment of candidemia are summarised. Investigational antifungal agents with potential activity against Candida bloodstream infections and other forms of invasive candidiasis and vaccines for prevention of Candida infections are also reviewed as are selected antifungal agents no longer in development. Antifungal agents currently in clinical trials include isavuconazole, albaconazole, SCY-078, VT-1161 and T-2307. Further data are needed to determine the role of these compounds in the treatment of candidemia and other forms of invasive candidiasis. The progressive reduction in antimicrobial drug development may result in a decline in antifungal drug discovery. Still, there remains a critical need for new antifungal agents to treat and prevent invasive candidiasis and other life-threatening mycoses.

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.

Invasive candidiasis in pediatric intensive care units

Candidemia and disseminated candidiasis are major causes of morbidity and mortality in hospitalized patients especially in the intensive care units (ICU). The incidence of invasive candidasis is on a steady rise because of increasing use of multiple antibiotics and invasive procedures carried out in the ICUs. Worldwide there is a shifting trend from C. albicans towards non albicans species, with an associated increase in mortality and antifungal resistance. In the ICU a predisposed host in one who is on broad spectrum antibiotics, parenteral nutrition, and central venous catheters. There are no pathognomonic signs or symptoms. The clinical clues are: unexplained fever or signs of severe sepsis or septic shock while on antibiotics, multiple, non-tender, nodular erythematous cutaneous lesions. The spectrum of infection with candida species range from superficial candidiasis of the skin and mucosa to more serious life threatening infections. Treatment of candidiasis involves removal of the most likely source of infection and drug therapy to speed up the clearance of infection. Amphotericin B remains the initial drug of first choice in hemodynamically unstable critically ill children in the wake of increasing resistance to azoles. Evaluation of newer antifungal agents and precise role of prophylactic therapy in ICU patients is needed.

Efficacy and toxicity of intermediate-dose amphotericin B lipid complex as a primary or salvage treatment of fungal infections in patients with hematological malignancies

We treated 74 adults with a hematological malignancy and documented or suspected invasive fungal infection (IFI) with amphotericin B lipid complex (ABLC) at 3 mg/kg/day. Forty-five patients (61%) received upfront therapy and 29 patients (39%) received salvage therapy for their IFI. Forty-eight of 71 evaluable patients responded [complete responses in 40 (56%) and partial responses in 8 (11%)] and 15 (21%) died as a consequence of the IFI. Response rates in invasive aspergillosis were 33 out of 49 (67%) for probable/definite cases and 6 out of 11 (55%) for invasive candidiasis. In 40 patients with neutropenia-associated IFI, rapid neutropenic recovery ( < 10 days from study entry) was essential for response to therapy (90% vs. 32%, P < 0.01). Treatment was well tolerated, with 15% infusions followed by infusion-related adverse events, nephrotoxicity in 7% of patients and 11% of withdrawals due to toxicity. These data suggest that intermediate-doses of ABLC may be of similar efficacy than higher doses with less toxicity, making it a cost-effective alternative worthy of study in future trials.

Clinical practice guidelines for the management of candidiasis: 2009 update by the Infectious Diseases Society of America

Guidelines for the management of patients with invasive candidiasis and mucosal candidiasis were prepared by an Expert Panel of the Infectious Diseases Society of America. These updated guidelines replace the previous guidelines published in the 15 January 2004 issue of Clinical Infectious Diseases and are intended for use by health care providers who care for patients who either have or are at risk of these infections. Since 2004, several new antifungal agents have become available, and several new studies have been published relating to the treatment of candidemia, other forms of invasive candidiasis, and mucosal disease, including oropharyngeal and esophageal candidiasis. There are also recent prospective data on the prevention of invasive candidiasis in high-risk neonates and adults and on the empiric treatment of suspected invasive candidiasis in adults. This new information is incorporated into this revised document.

Fungal pneumonia due to molds in patients with hematological malignancies

Invasive fungal infections are an important cause of morbidity and mortality in patients with hematological malignancies. In particular, patients with neutropenia and those who have undergone allogeneic hematopoietic stem cell transplantation are at highest risk, with fungal pneumonia being the main clinical manifestation in these patients. The most common pathogens associated with fungal pneumonia are Aspergillus spp. and Zygomycetes. However, other pathogens have also been observed in fungal pneumonia, including Cryptococcus spp., Pneumocystis jirovecii, and Candida spp. This comprehensive review will focus on the important practical aspects relevant to the epidemiology, clinical diagnosis, and therapeutic management of pneumonia due to filamentous fungi in patients affected by hematological malignancies.

Amphotericin B lipid complex for the treatment of invasive fungal infections

Amphotericin B lipid complex (ABLC; Abelcet, Enzon Pharmaceuticals) has become the dominant marketed lipid amphotericin B compound to emerge since the approval of these agents from the mid-1990s onwards. This agent is a 1:1 combination of amphotericin B and a lipid moiety consisting of dimyristoyl phosphatidylcholine and dimyrisoyl phosphatidylcholine, which exists in a ribbon-like molecular structure. ABLC undergoes rapid reticuloendothelial uptake from the circulation and achieves significantly higher tissue concentrations in the liver, spleen and lung compared to comparably dosed conventional amphotericin B. ABLC is approved by the FDA for all mycoses in amphotericin B-intolerant or -refractory infection. Randomised, controlled trials of amphotericin B have shown comparable efficacy in candidiasis and an improved outcome in invasive aspergillosis versus historical controls. ABLC has demonstrated a reduced incidence of nephrotoxicity and infusion reactions versus amphotericin B. Comparative studies against other lipid formulations are quite limited and have shown variable differences in infusion toxicity, nephrotoxicity, hepatotoxicity and clinical efficacy. Postapproval experience has shown substantial efficacy for less common mycotic pathogens including zygomycosis. The precise position of ABLC versus both other lipid formulations and expanding formulary of new antifungal agents is in flux. Future studies which examine its clinical efficacy, role in combination therapy, toxicity and cost-effectiveness in these complex patients are needed.

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.

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.

British Society for Medical Mycology proposed standards of care for patients with invasive fungal infections

Outcomes for invasive fungal infections have greatly improved in the past decade, and several new antifungal drugs have been or will be licensed in the next few years. Early accurate diagnosis and appropriate treatment have major impact on survival. In a 1995 survey of laboratory practice in the UK for mycology, major disparities were seen, with many laboratories not undertaking even simple diagnostic procedures. Delays in processing and inadequate procedures for handling samples, incomplete or delayed reporting of results, or a combination of these, compromise the care of patients. In randomised trials of antifungal chemotherapy, optimum treatments and good alternatives for others have been defined for some infections. High-quality care requires a multidisciplinary approach to diagnosis and management. In this review, we propose microbiology, histopathology, radiology, and clinical auditing standards, with the evidence base for each reviewed. The standards are absolutes, and, therefore, provide a straightforward basis for improving services to patients if they are all implemented.

Deeply invasive candidiasis

The incidence of invasive candidiasis is on the rise because of increasing numbers of immunocompromised hosts and more invasive medical technology. Recovery of Candida spp from several body sites in a critically ill or immunocompromised patient should raise the question of disseminated disease. Although identification to the species level and antifungal susceptibility testing should guide therapy, at this time amphotericin B preparations are the usual initial therapy for severe life-threatening disease. Azole therapy has an expanding body of evidence that proves it is as effective as and safer than amphotericin B therapy. Some forms of candidiasis (e.g., those with ocular, bone, or heart involvement) require a combined medical and surgical approach.

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.

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.

Antifungal pharmacodynamics: review of the literature and clinical applications

Invasive fungal infections are seen with growing frequency, likely due to increases in numbers of patients at risk of infection. Optimal selection and dosing of antifungal agents are important, as these infections are often refractory to available therapy. In contrast to antibacterials, studies examining the pharmacodynamic properties of antifungals and their application in treating invasive disease often are lacking. Agents administered for invasive infections are amphotericin B, flucytosine, and azole antifungals. Several drugs are under investigation, such as posiconazole, voriconazole, and the echinocandins, and preliminary pharmacodynamic data likely will help shape dosing regimens. Clinical trials that investigated dosage and administration, as well as the potential benefits of combination and sequential therapy, are addressed. In addition, antifungal susceptibility and animal models of infection are discussed.

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.