In vitro activity of a new echinocandin, LY303366, and comparison with fluconazole, flucytosine and amphotericin B against Candida species

Meyerozyma guilliermondii species complex: review of current epidemiology, antifungal resistance, and mechanisms

Meyerozyma guilliermondii has been accepted as a complex composed of Meyerozyma guilliermondii, Meyerozyma carpophila, and Meyerozyma caribbica. M. guilliermondii is a saprophyte detected on human mucosa and skin. It can lead to serious infections in patients with risk factors like chemotherapy, immunodeficiency, gastrointestinal or cardiovascular surgery, and oncology disorders. Most deaths related to M. guilliermondii infections occur in individuals with malignancy. In recent decades, incidence of M. guilliermondii infections is increased. Sensitivity of this microorganism to conventional antifungals (e.g., amphotericin B, fluconazole, micafungin and anidulafungin) was reduced. Prophylactic and empirical uses of these drugs are linked to elevated minimal inhibitory concentrations (MICs) of M. guilliermondii. Drug resistance has concerned many researchers across the world. They are attempting to discover appropriate solution to combat this challenge. This study reviews the most important mechanisms of resistance to antifungals developed by in M. guilliermondii species complex.

Caspofungin exposure-response relationships in adult patients with mucosal or invasive candidiasis

Caspofungin is an echinocandin antifungal agent administered once daily as an intravenous infusion. Relationships between caspofungin exposure and clinical efficacy and safety were investigated. End-of-infusion (CEOI ) and trough (C24 hours ) concentrations were obtained in 218 patients with mucosal (i.e., esophageal and/or oropharyngeal) candidiasis (MC) receiving caspofungin 35, 50, or 70 mg/day and 278 patients with invasive candidiasis (IC) receiving 50, 100, or 150 mg/day. Area under the plasma concentration-time curve (AUC0-24 hours ) was obtained in a subset of MC patients (n = 99). Odds ratios were estimated for the association between log-transformed PK and efficacy response and the occurrence of common adverse events. No pharmacokinetic or hybrid parameter (ratio of AUC:MIC, CEOI :MIC, C24 hours :MIC) was significantly correlated with overall treatment outcome in either MC or IC, although this patient population may exhibit confounding factors which masked a potential pharmacokinetic/pharmacodynamic relationship. An exploratory evaluation of MC identified significant pharmacokinetic correlations with endoscopic response, but not symptom response. Statistically significant associations were identified for IC patients with C. parapsilosis infections. Occurrence of clinical adverse events and/or laboratory abnormalities did not appear to be increased by higher caspofungin plasma concentrations. Caspofungin concentrations achieved with 50 mg/day are generally within the therapeutic window for the treatment of candidiasis.

Population pharmacokinetic-pharmacodynamic analysis of anidulafungin in adult patients with fungal infections

To evaluate the exposure-response relationships for efficacy and safety of intravenous anidulafungin in adult patients with fungal infections, a population pharmacokinetic-pharmacodynamic (PK-PD) analysis was performed with data from 262 patients in four phase 2/3 studies. The plasma concentration data were fitted with a previously developed population PK model. Anidulafungin exposures in patients with weight extremities (e.g., 40 kg and 150 kg) were simulated based on the final PK model. Since the patient population, disease status, and efficacy endpoints varied in these studies, the exposure-efficacy relationship was investigated separately for each study using logistic regression as appropriate. Safety data from three studies (n = 235) were pooled for analysis, and one study was excluded due to concomitant use of amphotericin B as a study treatment and different disease populations. The analysis showed that the same dosing regimen of anidulafungin can be administered to all patients regardless of body weight. Nonetheless, caution should be taken for patients with extremely high weight (e.g., >150 kg). There was a trend of positive association between anidulafungin exposure and efficacy in patients with esophageal candidiasis or invasive candidiasis, including candidemia (ICC); however, adequate characterization of the effect of anidulafungin exposure on response could not be established due to the relatively small sample size. No threshold value for exposure could be established, since patients with low exposure also achieved successful outcomes (e.g., area under the curve < 40 mg · h/liter in ICC patients). There was no association between anidulafungin exposure and the treatment-related adverse events or all-causality hepatic laboratory abnormalities.

Anidulafungin compared with fluconazole for treatment of candidemia and other forms of invasive candidiasis caused by Candida albicans: a multivariate analysis of factors associated with improved outcome

BACKGROUND

Candida albicans is the most common cause of candidemia and other forms of invasive candidiasis. Systemic infections due to C. albicans exhibit good susceptibility to fluconazole and echinocandins. However, the echinocandin anidulafungin was recently demonstrated to be more effective than fluconazole for systemic Candida infections in a randomized, double-blind trial among 245 patients. In that trial, most infections were caused by C. albicans, and all respective isolates were susceptible to randomized study drug. We sought to better understand the factors associated with the enhanced efficacy of anidulafungin and hypothesized that intrinsic properties of the antifungal agents contributed to the treatment differences.

METHODS

Global responses at end of intravenous study treatment in patients with C. albicans infection were compared post-hoc. Multivariate logistic regression analyses were performed to predict response and to adjust for differences in independent baseline characteristics. Analyses focused on time to negative blood cultures, persistent infection at end of intravenous study treatment, and 6-week survival.

RESULTS

In total, 135 patients with C. albicans infections were identified. Among these, baseline APACHE II scores were similar between treatment arms. In these patients, global response was significantly better for anidulafungin than fluconazole (81.1% vs 62.3%; 95% confidence interval [CI] for difference, 3.7-33.9). After adjusting for baseline characteristics, the odds ratio for global response was 2.36 (95% CI, 1.06-5.25). Study treatment and APACHE II score were significant predictors of outcome. The most predictive logistic regression model found that the odds ratio for study treatment was 2.60 (95% CI, 1.14-5.91) in favor of anidulafungin, and the odds ratio for APACHE II score was 0.935 (95% CI, 0.885-0.987), with poorer responses associated with higher baseline APACHE II scores. Anidulafungin was associated with significantly faster clearance of blood cultures (log-rank p < 0.05) and significantly fewer persistent infections (2.7% vs 13.1%; p < 0.05). Survival through 6 weeks did not differ between treatment groups.

CONCLUSIONS

In patients with C. albicans infection, anidulafungin was more effective than fluconazole, with more rapid clearance of positive blood cultures. This suggests that the fungicidal activity of echinocandins may have important clinical implications.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00058682.

Caspofungin use in patients with invasive candidiasis caused by common non-albicans Candida species: review of the caspofungin database

Increasing rates of invasive candidiasis caused by non-albicans Candida species have been reported worldwide. Particular concerns have been raised for C. parapsilosis because of reduced in vitro susceptibility to echinocandins. We identified 212 patients with invasive candidiasis due to non-albicans Candida species (>or=5 cases per species) in 5 clinical trials of caspofungin monotherapy from the pharmaceutical sponsor's (Merck and Co., Inc.) database: 71 cases were caused by C. parapsilosis, 65 by C. tropicalis, 54 by C. glabrata, 10 by C. krusei, 9 by C. guilliermondii, and 5 by C. lusitaniae. One hundred sixty-seven cases caused by C. albicans were also identified. Efficacy was assessed at the end of caspofungin therapy. Success (favorable overall response) required favorable clinical and microbiological responses. The mean APACHE II scores were 16.5 in the non-albicans group and 15.7 in the C. albicans group. Neutropenia at study entry was more common in the non-albicans group (12%) than in the C. albicans group (5%). The median duration of caspofungin therapy was 14 days in both groups. The success rates were 77% in both groups and at least 70% for each non-albicans species: 74% for C. parapsilosis, 71% for C. tropicalis, 85% for C. glabrata, 70% for C. krusei, 89% for C. guilliermondii, and 100% for C. lusitaniae. The times to negative blood culture were similar for the various species. The overall mortality rates were 26% in the non-albicans group and 29% in the C. albicans group. Drug-related serious adverse events and discontinuations due to caspofungin toxicity were uncommon. Although the sample sizes were limited, caspofungin demonstrated favorable efficacy and safety profiles in the treatment of invasive candidiasis caused by the following non-albicans Candida species: C. parapsilosis, C. tropicalis, C. glabrata, C. krusei, C. guilliermondii, and C. lusitaniae.

Changes in the proteome of Candida albicans in response to azole, polyene, and echinocandin antifungal agents

The yeast Candida albicans is an opportunistic human fungal pathogen and the cause of superficial and systemic infections in immunocompromised patients. The classes of antifungal agents most commonly used to treat Candida infections are the azoles, polyenes, and echinocandins. In the present study, we identified changes in C. albicans protein abundance using two-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption ionization-time of flight mass spectroscopy following exposure to representatives of the azole (ketoconazole), polyene (amphotericin B), and echinocandin (caspofungin) antifungals in an effort to elucidate the adaptive responses to these classes of antifungal agents. We identified 39 proteins whose abundance changed in response to ketoconazole exposure. Some of these proteins are involved in ergosterol biosynthesis and are associated with azole resistance. Exposure to amphotericin B altered the abundance of 43 proteins, including those associated with oxidative stress and osmotic tolerance. We identified 50 proteins whose abundance changed after exposure to caspofungin, including enzymes involved in cell wall biosynthesis and integrity, as well as the regulator of beta-1,3-glucan synthase activity, Rho1p. Exposure to caspofungin also increased the abundance of the proteins involved in oxidative and osmotic stress. The common adaptive responses shared by all three antifungal agents included proteins involved in carbohydrate metabolism. Some of these antifungal-responsive proteins may represent potential targets for the development of novel therapeutics that could enhance the antifungal activities of these drugs.

Candidemia in Patients with Ventricular Assist Devices

During the period 1998-2004, candidemia developed in 7 of 117 ventricular assist device recipients at our hospital, and the associated mortality rate was 71%. Five cases of candidemia were due to Candida parapsilosis, and 2 were due to Candida albicans. Three of the 7 patients with ventricular assist device-associated Candida bloodstream infections were cured, and the device was retained in 2 of the 3 patients.

Developments in the treatment of candidiasis: more choices and new challenges

The incidence of oesophageal candidiasis, candidaemia and disseminated candidiasis has increased dramatically. In addition to the amphotericin B formulations and fluconazole, the echinocandins anidulafungin, caspofungin and micafungin and the newer triazoles posaconazole and voriconazole are in the last stages of development and are becoming available for the management of candidiasis. This review presents these new agents and addresses their role in the treatment of candidiasis. All new antifungal agents exhibit potent activity against Candida spp. and echinocandins are fungicidal against most Candida spp. but appear to be less potent against certain species, such as Candida parapsilosis and C. guilliermondii. Systemic antifungal therapy can now be individualised based on the severity of the infection, comorbid conditions and the Candida spp. causing the infection. Studies are needed to investigate the possible development of resistance and the efficacy of these antifungal agents against the more resistant Candida spp.

Anidulafungin: a new echinocandin with a novel profile

BACKGROUND

Until recently, available treatment for serious fungal infections comprised amphotericin B and azoles, which have limitations. Renal toxicity is a major concern with amphotericin B, while drug-drug interactions, hepatotoxicity, and skin rashes are the primary concerns with the azole medications. The development of the echinocandins, including caspofungin, has helped to fill the need for more efficacious antifungals that are useful across different patient populations and have a good safety profile. Anidulafungin is an echinocandin being developed to treat mucosal and invasive fungal infections.

OBJECTIVE

The aim of this report was to describe the pharmacodynamic and pharmacokinetic (PK) properties of anidulafungin.

METHODS

Data were identified using MEDLINE and National Library of Medicine Gateway searches for English-language literature (key words: anidulafungin, esophageal candidiasis, echinocandin, caspofungin, ravuconazole, voriconazole, posaconazole, micafungin, and fluconazole; years: 1996-2004), and from meeting abstracts of the American Society for Blood and Marrow Transplantation (Arlington Heights, Illinois), European Congress of Clinical Microbiology and Infectious Diseases (Basel, Switzerland), International Conference on Antimicrobial Agents and Chemotherapy (Washington, DC), and Infectious Diseases Society of America (Arlington, Virginia).

RESULTS

Anidulafungin has potent in vitro activity against Aspergillus and Candida spp, including those resistant to either fluconazole or amphotericin B. Results of several clinical trials imply that anidulafungin is effective in treating esophageal candidiasis (EC), candidemia, and invasive candidiasis (IC). In a Phase III, randomized, blinded clinical trial evaluating anidulafungin (50 mg/d) versus fluconazole (100 mg/d) for the treatment of EC, 97.2% and 98.9% of patients who received anidulafungin and fluconazole, respectively, showed evidence of cure or improvement (treatment difference, -1.6%; 95% CI, -4.1 to 0.8). In a Phase II study of candidasis and candidemia, anidulafungin showed success rates of 72%, 85%, and 83% in patients receiving the drug at dosages of 50, 75, or 100 mg/d, respectively. Studies evaluating the concomitant use of anidulafungin and either amphotericin, voriconazole, or cyclosporine did not show clinically significant drug-drug interactions or altered adverse-event (AE) profiles (P < 0.05). A population PK analysis showed no significant effect of age, race, concomitant medications, or renal or hepatic insufficiency on the PK properties of anidulafungin (P < 0.05).

CONCLUSIONS

Anidulafungin may offer a new option to treat serious fungal infections, such as EC, azole-refractory EC, candidemia, and IC. In addition, anidulafungin has been associated with no clinically significant drug-drug interactions and few treatment-related AEs. Anidulafungin may offer a new option in the management of serious and difficult-to-treat invasive fungal infections.

Safety and pharmacokinetics of intravenous anidulafungin in children with neutropenia at high risk for invasive fungal infections

Anidulafungin is an echinocandin with activity against Candida species and Aspergillus species. Adult dosages under study are 50 mg/day for esophageal candidiasis and 100 mg/day for invasive candidiasis and aspergillosis. Little is known, however, about the safety and pharmacokinetics of anidulafungin in children. A multicenter, ascending-dosage study of neutropenic pediatric patients was therefore conducted. Patients were divided into two age cohorts (2 to 11 years and 12 to 17 years) and were enrolled into sequential groups to receive 0.75 or 1.5 mg/kg of body weight/day. Blood samples were obtained following the first and fifth doses. Anidulafungin was assayed in plasma, and pharmacokinetic parameters were determined. Safety was assessed using National Cancer Institute (NCI) common toxicity criteria. Pharmacokinetic parameters were determined for 12 patients at each dosage (0.75 mg/kg/day or 1.5 mg/kg/day). Concentrations and drug exposures were similar for patients between age cohorts, and weight-adjusted clearance was consistent across age. No drug-related serious adverse events were observed. One patient had fever (NCI toxicity grade of 3), and one patient had facial erythema, which resolved with slowing the infusion rate. Anidulafungin in pediatric patients was well tolerated and can be dosed based on body weight. Pediatric patients receiving 0.75 mg/kg/day or 1.5 mg/kg/day have anidulafungin concentration profiles similar to those of adult patients receiving 50 or 100 mg/day, respectively.

Effectiveness of anidulafungin in eradicating Candida species in invasive candidiasis

In a phase 2 open-label, dose-ranging study in patients with candidemia, anidulafungin was effective in eradicating Candida albicans and other species of Candida. The anidulafungin MIC distribution showed that Candida albicans and C. glabrata were the most susceptible species and C. parapsilosis was the least susceptible species.

In vitro interactions of anidulafungin with azole antifungals, amphotericin B and 5-fluorocytosine against Candida species

Anidulafungin, an echinocandin, is in late stage development for the treatment of fungal infections. We investigated the activity of anidulafungin in combination with other antifungal agents (fluconazole, itraconazole, ketoconazole, amphotericin B and 5-fluorocytosine) against four isolates each of Candida albicans, Candida glabrata, Candida parapsilosis and Candida tropicalis, and two isolates of Candida krusei using a macrobroth chequerboard method with interactions evaluated by fractional inhibitory concentration indices (FICIs). Additive activity (FICI > 0.5 to 1) or indifference (FICI > 1 to < 4) was observed in 85 of 90 interactions of anidulafungin with another antifungal agent. Synergy with itraconazole (FICI<or=0.5) was observed for one strain of C. glabrata, and antagonism with ketoconazole (FICI>or=4), a drug rarely used systemically, was noted for four strains of C. tropicalis. The combination of anidulafungin and amphotericin B demonstrated additive activity for each of the 18 isolates of Candida tested. These results suggest additional studies are warranted, for example in animal models, to evaluate further the potential of combination antifungal therapy with anidulafungin for Candida infections.

Anidulafungin: a novel echinocandin

We evaluated the safety and efficacy of primary systemic chemotherapy (PSC) with docetaxel (DOC), epirubicin (EPI) and capecitabine (Xeloda:XLD) in 10 patients with advanced breast cancer. Their mean age was 54.7 years,and preoperative stages were IIB, seven cases; IIIA, two; and IV, one,respectively. The regimen consisted of XLD (2,400 or 3,000 mg/day) orally for 14 consecutive days, and DOC (60 or 70 mg/m2) and EPI (50 or 60 mg/m2) intravenously on day 8. This was repeated 4 times every 3 weeks. One patient discontinued this regimen after one course at her own request. Although the results revealed leucopenia and neutropenia of more than grade 3 in 8 and 10 patients,they could be treated on an outpatient basis with the use of G-CSF to maintain this regimen. Alopecia of grade 2 was found in all patients,neutropenic fever of more than 38.5 degrees C in 5,and hand-foot syndrome in 3. Downstaging after PSC was demonstrated in 7 cases (Stage IIB to I, three cases; IIB to IIA, three; and III A to I, one), with a response rate of 77.8%. Breast conserving therapy was performed in 8/10 patients. Pathological findings on cytological degeneration showed grade 0, one; grade 1a,seven; grade 2, one; and grade 3, one, respectively. Axillary lymph node metastasis was revealed in 7 cases. This regimen would be an alternative to PSC on an outpatient basis while taking great care of myelosuppression and hand-foot syndrome.

Multiechinocandin- and multiazole-resistant Candida parapsilosis isolates serially obtained during therapy for prosthetic valve endocarditis

Echinocandins are approved for the treatment of candidal infections. In vitro they have been shown to be less potent against strains of Candida parapsilosis than against other Candida spp. This is the first case report describing the development of a secondary multidrug (echinocandin-azole)-resistant Candida strain during therapy.

A Randomized, Double-Blind Trial of Anidulafungin versus Fluconazole for the Treatment of Esophageal Candidiasis

Anidulafungin is a novel antifungal agent of the echinocandin class. This randomized, double-blind, double-dummy study compared the efficacy and safety of intravenous anidulafungin to that of oral fluconazole in 601 patients with endoscopically and microbiologically documented esophageal candidiasis. Patients received intravenous anidulafungin (100 mg on day 1, followed by 50 mg per day) or oral fluconazole (200 mg on day 1, followed by 100 mg per day) for 7 days beyond resolution of symptoms (range, 14-21 days). At the end of therapy, the rate of endoscopic success for anidulafungin (242 [97.2%] of 249 treated patients) was found to be statistically noninferior to that for fluconazole (252 [98.8%] of 255 treated patients; treatment difference, -1.6%; 95% confidence interval, -4.1 to 0.8). The safety profile of anidulafungin was similar to that of fluconazole; treatment-related adverse events occurred in 9.3% and 12.0% of patients, respectively. Laboratory parameters were similar between treatment arms. Anidulafungin is as safe and effective as oral fluconazole for the treatment of esophageal candidiasis, when assessed at the completion of therapy.

Population pharmacokinetic analysis of anidulafungin, an echinocandin antifungal

The objective of this analysis was to describe the pharmacokinetic characteristics of anidulafungin in patients with serious fungal disease based on pharmacokinetic data collected during four recently completed or ongoing Phase II/III clinical studies. A total of 600 anidulafungin plasma samples from 225 patients across the four studies were available for analysis. Patients received daily intravenous infusions of 50, 75, or 100 mg anidulafungin, preceded by a loading dose that was twice the daily dose. The analysis population consisted of 129 patients with esophageal candidiasis, 87 with invasive candidiasis, 7 with invasive aspergillosis, and 2 with azole refractory mucosal candidiasis. A population analysis approach was used to develop a steady-state pharmacokinetic model for anidulafungin, assess the significance of possible covariates, and determine the amount of intersubject and random residual variability. A two-compartment model with first-order elimination provided the best fit to the data. The clearance of anidulafungin was influenced by weight and gender, and subjects in the invasive candidiasis study had a typical clearance that was approximately 30% higher than subjects from other studies. Weight was determined to be a predictor of the central volume of distribution. The covariates on clearance accounted for less than 20% of the intersubject variability and therefore are deemed to be of little clinical relevance. There was no evidence that the presence of rifampin or metabolic substrates, inhibitors, or inducers of cytochrome p450 influenced the clearance of anidulafungin. This indicates that dosing adjustments are not necessary when anidulafungin is administered in the presence of medications falling into these classifications.

Anidulafungin

Anidulafungin is a novel antifungal agent which, like other echinocandins, inhibits beta-(1,3)-D-glucan synthase and disrupts fungal cell-wall synthesis. It has marked antifungal activity against a broad spectrum of Candida spp. and Aspergillus spp., including amphotericin B- and triazole-resistant strains. In clinical trials, anidulafungin has primarily been evaluated in patients with oesophageal and invasive candidiasis. Preliminary data are emerging for other indications such as invasive aspergillosis. In a large, multicentre, double-blind, double-dummy, randomised trial in patients with oesophageal candidiasis, intravenous anidulafungin 50 mg/day was as effective as oral fluconazole 100 mg/day regarding end-of-treatment rates of endoscopic cure and clinical and microbiological success. Duration of treatment was approximately 2-3 weeks, and patients in both groups received a loading dose of study drug (twice the daily maintenance dose) on day 1. Anidulafungin is generally well tolerated. Across the dosage range 50-100 mg/day, adverse events appear not to be dose- or infusion-related. In the largest clinical trial to date, the most common treatment-related adverse events were phlebitis/thrombophlebitis, headache, nausea, vomiting and pyrexia.

Clinical impact of the fungicidal activity of caspofungin administered alone or in combination in critically ill patients with severe abdominal candidiasis refractory to conventional antifungal drugs: case studies and critical review of the problem

We discuss two cases of abdominal candidiasis in critically ill patients with multiple organ failure and sepsis. Microbiological and clinical courses remained unresponsive to apparently appropriate antifungal therapy with azole or polyene derivatives. Both microbiological and clinical outcomes dramatically improved after starting caspofungin therapy. Lack of cross-resistance, lack of toxicity and potent fungicidal activity make caspofungin a very attractive drug in life threatening abdominal candidiasis. The optimal treatment of life threatening candidiasis remains a controversial issue. Because of recent advances in the field, we propose a critical review of the problem of refractory candidiasis.

Newer Systemic Antifungal Agents

The past few years have seen the advent of several new antifungal agents, including those of a new class and a new generation of an existing class. Caspofungin, the first available echinocandin, has greatly expanded the antifungal armamentarium by providing a cell wall-active agent with candidacidal activity as well as demonstrated clinical efficacy in the therapy of aspergillosis refractory to available therapy. In addition, in clinical trials, caspofungin had comparable efficacy to amphotericin B for candidaemia and invasive Candida infections. Caspofungin and two more recently introduced echinocandins, micafungin and anidulafungin, are available as intravenous formulations only and characterised by potent anti-candidal activity, as well as few adverse events and drug interactions. Voriconazole, the first available second-generation triazole, available in both intravenous and oral formulations, has added a new and improved therapeutic option for primary therapy of invasive aspergillosis and salvage therapy for yeasts and other moulds. In a randomised trial, voriconazole demonstrated superior efficacy and a survival benefit compared with amphotericin B followed by other licensed antifungal therapy. This and data from a noncomparative study led to voriconazole becoming a new standard of therapy for invasive aspergillosis. Voriconazole has several important safety issues, including visual adverse events, hepatic enzyme elevation and skin reactions, as well as a number of drug interactions. Posaconazole, only available orally and requiring dose administration four times daily, shows encouraging efficacy in difficult to treat infections due to zygomycetes. Ravuconazole, available in both intravenous and oral formulations, has broad-spectrum in vitro potency and in vivo efficacy against a wide range of fungal pathogens. Clinical studies are underway. Despite the advances offered with each of these drugs, the morbidity and mortality associated with invasive fungal infections remains unacceptable, especially for the most at-risk patients. For individuals with severe immunosuppression as a result of chemotherapy, graft-versus-host disease and its therapy, or transplantation, new drugs and strategies are greatly needed.

Echinocandin antifungal drugs

The echinocandins are large lipopeptide molecules that are inhibitors of beta-(1,3)-glucan synthesis, an action that damages fungal cell walls. In vitro and in vivo, the echinocandins are rapidly fungicidal against most Candida spp and fungistatic against Aspergillus spp. They are not active at clinically relevant concentrations against Zygomycetes, Cryptococcus neoformans, or Fusarium spp. No drug target is present in mammalian cells. The first of the class to be licensed was caspofungin, for refractory invasive aspergillosis (about 40% response rate) and the second was micafungin. Adverse events are generally mild, including (for caspofungin) local phlebitis, fever, abnormal liver function tests, and mild haemolysis. Poor absorption after oral administration limits use to the intravenous route. Dosing is once daily and drug interactions are few. The echinocandins are widely distributed in the body, and are metabolised by the liver. Results of studies of caspofungin in candidaemia and invasive candidiasis suggest equivalent efficacy to amphotericin B, with substantially fewer toxic effects. Absence of antagonism in combination with other antifungal drugs suggests that combination antifungal therapy could become a general feature of the echinocandins, particularly for invasive aspergillosis.

Systemic mycoses in the immunocompromised host: an update in antifungal therapy

Despite significant advances in the management of immunosuppressed patients, invasive fungal infections remain an important life-threatening complication. In the last decade several new antifungal agents, including compounds in pre-existing classes (new generation of triazoles, polyenes in lipid formulations) and novel classes of antifungals with a unique mechanism of action (echinocandins), have been introduced in clinical practice. Ongoing and future studies will determine their exact role in the management of different mycoses. The acceleration of antifungal drug discovery offers promise for the management of these difficult to treat opportunistic infections.

Recent advances in the epidemiology, prevention, diagnosis, and treatment of fungal pneumonia

Although pneumonia caused by fungi is not a common occurrence in the general population, disease in an enlarging immunocompromised population is encountered with increasing frequency. Fungal pneumonias are most frequently caused by Aspergillus spp., dimorphic fungi and Cryptococcus neoformans. Recent studies have identified risk factors of thrombocytopenia, environmental events (such as construction or renovation) and immunosuppressive drug therapies as being specific risk factors for invasive fungal disease in select patient populations. Diagnostic strategies to detect circulating antigens and polymerase chain reaction based detection systems have been explored to improve identification prior to the progressive advanced disease. Advances in prophylactic strategies include increased use of aerosolized formulations of amphotericin B, usually in conjunction with new and old systemic antifungal agents. Despite recent published guidelines for treatment of fungal pneumonia based on etiology, mortality remains high in some infections with advanced disease. Caspofungin, a new echinocandin antifungal, has recently been approved by the US Food and Drug Administration for the treatment of invasive Aspergillus infections in patients unresponsive to or unable to receive amphotericin B. A triazole antifungal, voriconazole, has shown promise in phase III clinical trials in patients with refractory fungal infections and is expected to be available in early 2002. Other echinocandin and triazole antifungals are under development in attempts to provide improved effective therapy for fungal pneumonia.