Voriconazole compared with liposomal amphotericin B for empirical antifungal therapy in patients with neutropenia and persistent fever

Central nervous system Aspergillus fumigatus infection after near drowning

AIMS

To report the case of a 26 year old white man, who developed chronic meningitis and intracerebral granulomata 15 days after an episode of near drowning in a swamp.

METHODS

Aspergillus fumigatus was isolated from cerebrospinal fluid cultures.

RESULTS

The patient died 70 days after the symptoms were first noticed, and seven days after a subarachnoid haemorrhage. Aspergillus has never been reported before as a cause of intracranial infection after near drowning.

CONCLUSIONS

Physicians must be aware of this possibility when confronted with such a situation, because there are now effective therapeutic options for systemic aspergillosis.

New and emerging antifungal agents: impact on respiratory infections

Fungal pathogens are increasingly important causes of respiratory disease, yet the number of antifungal agents available for clinical use is limited. Use of amphotericin B deoxycholate is hampered by severe toxicity. Triazole agents currently available have significant drug interactions; fluconazole has a limited spectrum of activity and itraconazole was, until recently, available only in oral formulations with limited bioavailability. The development of resistance to all three agents is increasingly being recognized and some filamentous fungi are resistant to the action of all of these agents. In the past few years, new antifungal agents and new formulations of existing agents have become available.The use of liposomal amphotericin B preparations is associated with reduced, but still substantial, rates of nephrotoxicity and infusion-related reactions. An intravenous formulation of itraconazole has been introduced, and several new triazole agents have been developed, with the view of identifying agents that have enhanced potency, broader spectra of action and improved pharmacodynamic properties. One of these, voriconazole, has completed large-scale clinical trials. In addition, caspofungin, the first of a new class of agents, the echinocandins, which inhibit cell wall glucan synthesis, was approved for use in the US in 2001 as salvage therapy for invasive aspergillosis. It is hoped that the availability of these agents will have a significant impact on the morbidity and mortality of fungal respiratory infections. However, at the present time, our ability to assess their impact is limited by the problematic nature of conducting trials for antifungal therapy.

Newer antifungal agents

Invasive fungal infections have evolved into significant causes of morbidity and mortality in premature infants, immunocompromised children, and patients receiving immunosuppressive agents. Since the discovery in 1955, amphotericin B has been the cornerstone of antifungal treatment. The past 10 years, however, have witnessed a major expansion in the antifungal armamentarium through the development of less toxic formulations of Amphotericin B, the introduction of improved triazoles, and the advent of the echinocandin lipopeptides. In this article we discuss the Lipid-based amphotericin B, Voriconazole (a new azole), and Caspofungin (an echinocandin).

Amphotericin-induced stridor: a review of stridor, amphotericin preparations, and their immunoregulatory effects

BACKGROUND

Various adverse effects have been reported with the use of amphotericin B. The respiratory adverse effects include dyspnea, tachypnea, bronchospasm, hemoptysis, and hypoxemia. Stridor has not been previously reported with the use of amphotericin B.

OBJECTIVE

To review the mechanism of action and reports of respiratory adverse effects for amphotericin B, the liposomal preparations of amphotericin B, and the differential diagnosis of stridor.

DATA SOURCES

A MEDLINE search from 1966 to 2002 was performed to review the current literature for possible mechanisms and immunoregulatory effects related to the infusion of amphotericin B.

RESULTS

Amphotericin B has been shown to increase tumor necrosis factor alpha (TNF-alpha) concentrations in macrophages. In addition, it induces prostaglandin E2 synthesis and increases the production of interleukin 1beta (IL-1beta) in mononuclear cells. The immunoregulatory effects of amphotericin B include increases in apoptosis, production of monocyte chemoattractant protein 1, superoxide anion, nitric oxide, and intercellular adhesion molecule 1 expression.

CONCLUSIONS

Amphotericin B induces the production of TNF-alpha, interferon-gamma, and IL-1beta, which may potentiate its toxic effects. Some liposomal preparations induced lower levels of TNF-alpha and nitric oxide and may be useful in patients unable to tolerate amphotericin B deoxycholate.

New antifungal agents

With the relentless increase in invasive fungal infections, particularly in critically ill and immunocompromised patients, it is good to know that there are new additions to the antifungal armamentarium. These include not only new formulations of existing drugs and the development of new triazole agents, but also the introduction of a new class of antifungal drug.

Oral versus intravenous therapy in the treatment of systemic mycosis

The great majority of systemic fungal infections require long-term therapy that often extends 6-12 months, particularly in immunosuppressed patients. It can be difficult to comply with this requirement when the drug to be used is only available for intravenous administration, because problems related to maintaining a permeable venous pathway for long periods arise. The availability of an intravenously (IV) and orally (PO) administered drug can solve this problem by making sequential therapy possible. Voriconazole is a new antifungal agent that, apart from satisfying this requirement because it has a high oral bioavailability, presents a broad spectrum of antifungal activity that makes its use possible, a priori, in the initial and/or sequential IV/PO treatment of any systemic mycotic infection. Based on current costs there is potential for savings compared with liposomal amphotericin B.

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.

Metaanálisis de la seguridad y eficacia de la anfotericina B liposómica en el tratamiento empírico de la neutropenia febril

BACKGROUND AND OBJECTIVE

We compared the safety and efficacy of liposomal amphotericin B with other formulations of amphotericin B and voriconazol as an empirical treatment of febrile neutropenia.

MATERIAL AND METHOD

Several randomized controlled clinical trials, designed to evaluate the safety and/or efficacy of liposomal amphotericin B in the empirical treatment of febrile neutropenia, in comparison with other amphotericin B formulations or voriconazol, were identified by means of a search in MEDLINE, EMBASE and Cochrane Controlled Trials Register's data bases. American Society of Microbiology and American Society of Clinical Oncology abstracts, presented between 1999 and 2002, were also included in the search. Prior to data extraction, concepts like nephrotoxicity, infusion-related adverse events and efficacy (success rate and mortality) were defined.

RESULTS

Two studies comparing liposomal amphotericin B with conventional amphotericin B, one comparing liposomal amphotericin B with amphotericin B lipid complex and one comparing liposomal amphotericin B with voriconazol were included in the analysis. Patients treated with liposomal amphotericin B had lower nephrotoxicity than patients treated with other amphotericin B formulations or with conventional amphotericin B (RR = 0.49); conversely, no statistically significant differences with regard to voriconazol were observed. In terms of efficacy, mortality rate and therapeutic failure, patients treated with limposomal amphotericin B showed a slightly higher efficacy.

CONCLUSIONS

Liposomal amphotericin B is a lipidic formulation with a slightly higher efficacy than other amphotericin B formulations and voriconazol. In terms of nephrotoxicity, liposomal amphotericin B showed lower nephrotoxicity than other amphotericines while its safety rates were similar to those of voriconazol.

Invasive cutaneous fungal infections requiring radical resection in cancer patients undergoing chemotherapy

Invasive fungal infections have emerged as a significant problem in patients with cancer with the development of better systemic therapies for malignancy and more effective antibacterial agents. The currently available world published medical literature was reviewed on invasive fungal infections in cancer patients with specific attention devoted to the multidisciplinary role of surgery in refractory cutaneous cases. Infections can develop on the forearm where peripheral intravenous catheters had been inserted in cancer patients undergoing cytotoxic chemotherapy. Curative intent begins with systemic contemporary anti-fungal therapy. Following resolution of neutropenia, patients may require radical surgical debridement with negative margins of resection for complete eradication of the fungal infection. Although invasive fungal infections refractory to antifungal systemic therapy in immunocompromised patients undergoing chemotherapy are a rare event, it is critical for surgeons and other multidisciplinary clinicians to recognize these potentially life-threatening infections that may necessitate radical surgical resection for cure.

Voriconazole for serious fungal infections

Voriconazole is a new second generation triazole effective against a wide spectrum of fungal pathogens. A randomised, controlled trial has shown it to be superior to amphotericin B in invasive aspergillosis, and it is a potential alternative to amphotericin B in neutropenic sepsis and to fluconazole in oesophageal candidiasis. Early clinical reports and in vitro susceptibility data suggest that it may also be a valuable antifungal against fluconazole-resistant Candida species and certain emerging fungal pathogens, which cause infections that are often refractory to conventional therapies. There is limited evidence of azole cross-resistance of clinical importance. Voriconazole is available as intravenous and oral formulations and has excellent tissue penetration and a good safety profile, the main problems being transient visual impairment and hepatotoxicity in patients with liver disease. It is metabolised by cytochrome P-450 isoenzymes causing important drug interactions but, in contrast to amphotericin B, is safe in renal failure and rarely causes infusion-related reactions. This review outlines the pharmacology of voriconazole and focuses on its clinical applications and safety profile.

[Therapy of severe fungal infections]

Severe fungal infections increase in numbers in the Western world. This is due to more intensive therapies against cancers leading to severe and prolonged immunosuppression. For many years treatment of severe fungal infections had to be done solely with amphothericin B desoxycholate and 5-fluorocytosine. With the advent of triazoles such as fluconazole, lipid formulations of amphotericin B and the development of echinocandines such as caspofungin also severe candidiasis and invasive aspergillosis has become treatable. In particular, caspofungin for invasive candidiasis and voriconazole for invasive aspergillosis seem at least equivalent to amphotericin B. A clear advantage is the advent of lipid formulations of amphotericin B. This regards especially side effects which are reduced with these newer formulations, i.e. nephrotoxicity. Due to the fact that prospective trials are difficult to conduct because patient populations may vary considerably (especially the underlying disease) many comparisons were not yet performed. Nevertheless, promising results indicate that certain combinations of antifungals may enhance prognosis of refractory fungal infections with a so far very serious prognosis.

Determinants of Candidemia and Candidemia-Related Death in Cardiothoracic ICU Patients

STUDY OBJECTIVES

To develop and prospectively validate models of independent predictors of candidemia and candidemia-related death in cardiothoracic ICU (CICU) patients.

DESIGN

(1) An initial, prospective, one-center, case-control, independent predictor-model determining study; and (2) a prospective, two-center, model-validation study.

SETTING

The initial study was performed at the 14-bed CICU of the Onassis Cardiac Surgery Center, Athens, Greece; the model-validation study was performed at the Onassis Cardiac Surgery Center CICU and the 12-bed CICU of Henry Dunant General Hospital, Athens, Greece.

PATIENTS

In the initial study, 4,312 patients admitted to the Onassis Center CICU between March 1997 and October 1999 were considered for enrollment; 30 candidemic and 120 control patients (case/control ratio, 1/4) matched according to potential confounders were ultimately enrolled. In the model-validation study, 2,087 patients admitted to the Onassis and Henry Dunant CICUs between November 1999 and May 2002 were prospectively enrolled.

MEASUREMENTS AND RESULTS

Models of predictors of candidemia and associated death were constructed with stepwise logistic regression and subsequently validated. Independent candidemia predictors were ongoing invasive mechanical ventilation (IMV) > OR =10 days, hospital-acquired bacterial infection and/or bacteremia, cardiopulmonary bypass duration > 120 min, and diabetes mellitus. Model performance was as follows: sensitivity, 53.3%/57.9%; specificity, 100%/100%; positive predictive value (PPV), 100%/100%; negative predictive value (NPV), 88.9%/99.6%; and accuracy, 90.1%/99.6% (initial/model-validation study values, respectively). IMV > or =10 days and hospital-acquired bacterial infection/bacteremia were the two strongest candidemia predictors. APACHE (acute physiology and chronic health evaluation) II score > or =30 at candidemia onset independently predicted candidemia-related death with 80.0%/85.7% sensitivity, 80%/75% specificity, 66.7%/66.7% PPV, 88.9%/88.9% NPV, and 80.0%/78.9% accuracy (initial/model-validation study values, respectively).

CONCLUSIONS

We provided a set of easily determinable independent predictors of the occurrence of candidemia in CICU patients. Our results provide a rationale for implementing preventive measures in the form of independent predictor control, and initiating antifungal prophylaxis in high-risk CICU patients.

Nouveaux antifongiques : voriconazole et caspofungine

Among new available antifungal agents voriconazole is a new triazole with an intravenous (i.v.) and oral formulation, and caspofungin is an echinocandin, new family with a new mode of action on the cell wall. It is available as an i.v. preparation. Both drugs have a broad spectrum targeting most of the usual pathogens: Candida and Aspergillus, even with low suceptibility or resistance to other antifungals. Voriconazole is also active on Scedosporium and Fusarium. The efficacy of these molecules was established in vitro and in experimental infections in animals either normal or immunosuppressed. Voriconazole is active in oropharyngeal and esophageal candidiasis, in refractory invasive candidiasis and as a first line treatment of invasive aspergillosis with better results than amphotéricine B. It was also effective in scedosporiosis and in fusariosis. Caspofungin is active in oropharyngeal and esophageal candidiasis, in invasive candidiasis ranking among the best drugs in non neutropenic patients. It was shown effective in refractory aspergillosis. As empirical treatment of febrile neutropenic patients, these molecules should probably be restricted to the highest risk-population. Safety is good, side effects are a rare cause of discontinuation of treatment, class specific drug-drug interactions occur with voriconazole. These molecules open an important field of investigations with combination of antifungal agents.

Systemic Antifungal Therapy: New Options, New Challenges

The frequency of invasive fungal infections has increased dramatically in recent decades because of an expanding population at risk. Until now, treatment options for invasive mycoses have been primarily amphotericin B and the azoles, fluconazole and itraconazole. Traditional agents are limited by an inadequate spectrum of activity, drug resistance, toxicities, and drug-drug interactions. The recent approval of caspofungin and voriconazole clearly has expanded the number of existing antifungal drugs available. However, the enthusiasm that accompanies their availability is counterbalanced by limited clinical experience, high drug acquisition costs, and distinctive toxicities. The pharmacologic characteristics, extent of clinical experience (efficacy and toxicity), and drug acquisition costs among available systemic antifungal agents are compared, with emphasis on the new agents. Also, recommendations on the role of each agent are provided according to the most common indications for systemic antifungal therapy: invasive candidiasis, invasive aspergillosis, and febrile neutropenia.

Infections in patients with cancer undergoing chemotherapy: aetiology, prevention, and treatment

Patients with cancer who are undergoing chemotherapy are highly susceptible, especially if neutropenic, to almost any type of bacterial or fungal infection. These infections cause substantial morbidity and mortality. Prophylactic use of antibiotics should be avoided, however, since this practice is associated with a risk of emergence of resistant bacteria and it does not lower the risk of death. However, chemoprophylaxis has a role for candidal fungal infections. Because infection in a neutropenic host can be rapidly fatal if not treated, the empirical administration of broad-spectrum intravenous antibiotics is generally indicated for these patients, and the local frequencies, susceptibility, and resistance patterns of various pathogens must be taken into account. Once therapy has been initiated, changes in antibiotic regimens during the first 5 days are useless unless the patient's clinical condition deteriorates substantially. The treatment of invasive fungal infections is particularly difficult. Many unsolved questions remain, and studies are proposed here that may shed light on these issues.

Liver failure in a child receiving highly active antiretroviral therapy and voriconazole

We describe a 10-year-old child with vertically transmitted acquired immunodeficiency syndrome who was receiving antiretroviral combination therapy and died of liver failure after beginning voriconazole therapy.

Voriconazole treatment of presumptive disseminated Aspergillus infection in a child with acute leukemia

Invasive fungal infection continues to pose a significant threat to immunocompromised patients. The authors describe a pediatric patient receiving chemotherapy for acute undifferentiated leukemia who developed presumptive Aspergillus species infection disseminated to lung, liver, spleen, and bone. The authors report the successful treatment of this infection with the addition of voriconazole, a triazole antimycotic, to treatment with amphotericin and surgical debridement, in the setting of ongoing intensive chemotherapy.

Successsful voriconazole treatment of disseminated fusarium infection in an immunocompromised patient

Fusarium infection is known to cause major morbidity and mortality in immunocompromised hosts. We report the successful treatment of disseminated Fusarium infection with skin manifestations in a severely neutropenic, immunocompromised host with voriconazole, a new second-generation triazole. Voriconazole might be an alternative therapy for patients with neutropenia who have fusariosis that is refractory or unresponsive to amphotericin B or its liposomal formulation.

New antifungal agents

Currently, use of standard antifungal therapies can be limited because of toxicity, low efficacy rates, and drug resistance. New formulations are being prepared to improve absorption and efficacy of some of these standard therapies. Various new antifungals have demonstrated therapeutic potential. These new agents may provide additional options for the treatment of superficial fungal infections and they may help to overcome the limitations of current treatments. Liposomal formulations of AmB have a broad spectrum of activity against invasive fungi, such as Candida spp., C. neoformans, and Aspergillus spp., but not dermatophyte fungi. The liposomal AmB is associated with significantly less toxicity and good rates of efficacy, which compare or exceed that of standard AmB. These factors may provide enough of an advantage to patients to overcome the increased costs of these formulations. Three new azole drugs have been developed, and may be of use in both systemic and superficial fungal infections. Voriconazole, ravuconazole, and posaconazole are triazoles, with broad-spectrum activity. Voriconazole has a high bioavailability, and has been used with success in immunocompromised patients with invasive fungal infections. Ravuconazole has shown efficacy in candidiasis in immunocompromised patients, and onychomycosis in healthy patients. Preliminary in vivo studies with posaconazole indicated potential use in a variety of invasive fungal infections including oropharyngeal candidiasis. Echinocandins and pneumocandins are a new class of antifungals, which act as fungal cell wall beta-(1,3)-D-glucan synthase enzyme complex inhibitors. Caspofungin (MK-0991) is the first of the echinocandins to receive Food and Drug Administration approval for patients with invasive aspergillosis not responding or intolerant to other antifungal therapies, and has been effective in patients with oropharyngeal and esophageal candidiasis. Standardization of MIC value determination has improved the ability of scientists to detect drug resistance in fungal species. Cross-resistance of fungal species to antifungal drugs must be considered as a potential problem to future antifungal treatment, and so determination of susceptibility of fungal species to antifungal agents is an important component of information in development of new antifungal agents. Heterogeneity in susceptibility of species to azole antifungals has been noted. This heterogeneity suggests that there are differences in activity of azoles, and different mechanisms of resistance to the azoles, which may explain the present lack of cross-resistance between some azoles despite apparent structural similarities. The mechanisms of azole action and resistance themselves are not well understood, and further studies into azole susceptibility patterns are required.

New antifungal drugs and new clinical trials: interpreting results may be difficult

PURPOSE OF REVIEW

In recent years, considerable progress in the management of invasive mycoses in immunocompromised patients has been achieved. However, the prognosis of these infections, in particular those caused by filamentous fungi, continues to be dramatically poor, with mortality rates reaching more than 80% in selected categories of patients. New antifungal drugs in the classes of triazoles and echinocandins, with interesting antimicrobial and pharmacokinetic characteristics, are under investigation, and important trials have been reported in the last 2 years. These studies seem to suggest the relevant role of these new drugs in the antifungal armamentarium.

RECENT FINDINGS

The triazole voriconazole and the echinocandin caspofungin demonstrated significant advantages in term of toxicity and response rate, when compared with conventional amphotericin B in the treatment of aspergillosis and candidiasis, respectively. However, because of the peculiar characteristics of the design of both studies, the interpretation of the results may be difficult, and further confirmatory experiences are needed. Other noncontrolled studies showed a promising role of caspofungin in the treatment of Aspergillus infections and of voriconazole in the treatment of other rare mycoses.

SUMMARY

The increasing incidence and severity of invasive mycoses have led to the development of new strategies with new antifungal agents, and amphotericin B no longer is the gold standard for a variety of fungal infections. However, these results should be considered with caution. The latest generation drugs need to be investigated further in proper trials, and old drugs, especially conventional amphotericin B, continue to have a central role in the antifungal armamentarium.

[Amphotericin B and its lipid formulations]

More than 40 years after its approval, Amphotericin B is still the gold standard in the treatment of invasive fungal infections due to Candida and Aspergillus spp. Three different lipid formulations of Amphotericin B have been available for over 10 years, with only one of them, i.e. liposomal Amphotericin B (Ambisome), approved in Germany. Liposomal Amphotericin B is superior to conventional Amphotericin B due to its reduced nephrotoxicity, the option of a higher initial loading-dose, and fewer infusion-related side-effects, all this with identical or even higher efficacy.

[Voriconazole - applications and perspectives]

Voriconazole (Vfend) is a new broadspectrum antifungal agent belonging to the group of triazole drugs. In vitro and in vivo efficacy was demonstrated against a large variety of yeasts with excellent activity against all Candida species but as well against Cryptococcus neoformans. Furthermore, voriconazole has shown excellent activity against many moulds in particular against Aspergillus species, but endemic fungi such as Histoplasma capsulatum are in the spectrum as well. Clinical efficacy was demonstrated in several large phase II/III studies in diseases such as oral and oesophageal candidosis, acute invasive aspergillosis or chronic invasive aspergillosis. New adverse events such as visual disturbancies has been described together with the use of voriconazole, but the majority of adverse events are similar to other triazole drugs and in particular not life-threatening. With the introduction of voriconazole a great progress in the therapy of invasive fungal infections was achieved. In the therapy of invasive aspergillosis, voriconazole is significantly more effective compared to amphotericin B desoxycholate.

Triad of acute infusion-related reactions associated with liposomal amphotericin B: analysis of clinical and epidemiological characteristics

We investigated the clinical characteristics and treatment of patients with a distinctive triad of acute infusion-related reactions (AIRRs) to liposomal amphotericin B (L-AMB) via single-center and multicenter analyses. AIRRs occurred alone or in combination within 1 of 3 symptom complexes: (1) chest pain, dyspnea, and hypoxia; (2) severe abdomen, flank, or leg pain; and (3) flushing and urticaria. The frequency of AIRRs in the single-center analysis increased over time. Most AIRRs (86%) occurred within the first 5 min of infusion. All patients experienced rapid resolution of symptoms after intravenous diphenhydramine was administered. The multicenter analysis demonstrated a mean overall frequency of 20% (range, 0%-100%) of AIRRs among 64 centers. A triad of severe AIRRs to L-AMB may occur in some centers; most of these reactions may be effectively managed by diphenhydramine administration and interruption of L-AMB infusion.

Fungal pneumonias in transplant recipients

Fungi are ubiquitous in the environment. Opportunistic fungal pneumonias in the immunocompromised host continue to increase most commonly due to Aspergillus sp. Affected patients are usually hematopoietic stem cell and lung transplant recipients. Clinical presentation is protean, and the diagnosis is challenging. Culture of respiratory specimens has limited utility. The detection of circulating fungal antigens and DNA seems promising, but more studies are needed. Value of prophylactic strategies or preemptive therapy remains contentious. New antifungal drugs for managing invasive pulmonary aspergillosis continue to emerge, with better safety, efficacy, and pharmacologic profiles.

Voriconazole treatment for less-common, emerging, or refractory fungal infections

Treatments for invasive fungal infections remain unsatisfactory. We evaluated the efficacy, tolerability, and safety of voriconazole as salvage treatment for 273 patients with refractory and intolerant-to-treatment fungal infections and as primary treatment for 28 patients with infections for which there is no approved therapy. Voriconazole was associated with satisfactory global responses in 50% of the overall cohort; specifically, successful outcomes were observed in 47% of patients whose infections failed to respond to previous antifungal therapy and in 68% of patients whose infections have no approved antifungal therapy. In this population at high risk for treatment failure, the efficacy rates for voriconazole were 43.7% for aspergillosis, 57.5% for candidiasis, 38.9% for cryptococcosis, 45.5% for fusariosis, and 30% for scedosporiosis. Voriconazole was well tolerated, and treatment-related discontinuations of therapy or dose reductions occurred for <10% of patients. Voriconazole is an effective and well-tolerated treatment for refractory or less-common invasive fungal infections.

Voriconazole

BACKGROUND

Reports of resistance and intolerance to currently available antifungal agents are increasing. Voriconazole is a broad-spectrum azole antifungal agent structurally derived from fluconazole. It is indicated for the treatment of invasive aspergillosis and serious fungal infections caused by Scedosporium apiospermum and Fusarium species in patients who are unable to tolerate or are refractory to other antifungal therapy.

OBJECTIVE

This article reviews the pharmacologic and pharmacokinetic properties and clinical usefulness of voriconazole.

METHODS

Relevant information was identified through a search of MEDLINE (1966-December 2002), Iowa Drug Information Service (1966-December 2002), International Pharmaceutical Abstracts (1970-December 2002), and meeting abstracts of the Infectious Diseases Society of America (1996-2002) and the Interscience Conference on Antimicrobial Agents and Chemotherapy (1996-2002) using the terms voriconazole and UK-109,495.

RESULTS

In head-to-head comparative trials, voriconazole appeared to be as efficacious as amphotericin B for the treatment of invasive aspergillosis and the empiric treatment of fungal infections in patients with febrile neutropenia. In clinical studies, it was as efficacious as fluconazole for the treatment of oropharyngeal and esophageal candidiasis. The results of in vitro susceptibility studies and case reports suggested that voriconazole may be useful against fluconazole- and/or itraconazole-resistant strains of Candida. Although voriconazole may be associated with a lower incidence of serious systemic adverse effects compared with amphotericin B (13.4% vs 24.3% in 1 pivotal clinical study; P = NS), major adverse effects associated with voriconazole include visual abnormalities ( approximately 30%), skin reactions ( approximately 20%), and elevations in hepatic enzymes (< or =20%). Voriconazole is available as oral and intravenous formulations. Pharmacokinetically, it has widespread distribution, including penetration into cerebral tissue. However, as 80% of voriconazole is hepatically eliminated, primarily via the cytochrome P450 (CYP) isozymes CYP2C19, CYP3A4, and CYP2C9, voriconazole has a high potential for drug interactions, and dose reduction is recommended in patients with mild to moderate hepatic dysfunction (Child-Pugh class A or B). Oral voriconazole may be preferred in patients with a creatinine clearance <50 mL/min due to the potential accumulation of the solubilizing excipient in the parenteral formulation of voriconazole.

CONCLUSIONS

Voriconazole appears to be a useful alternative to conventional antifungal agents in cases of resistance or intolerance to initial therapy. However, dose adjustment is recommended in patients with hepatic dysfunction, as well as in those receiving medications that may interact with voriconazole via hepatic metabolism.

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.

Forum report: issues in clinical trials of empirical antifungal therapy in treating febrile neutropenic patients

There is inferential evidence that some patients with prolonged neutropenia and fever not responding to antibacterial agents are at sufficient risk of deep mycoses to warrant empirical therapy, although superiority of an antifungal agent over placebo has not been conclusively demonstrated. Amphotericin B deoxycholate, liposomal amphotericin B, and intravenous itraconazole followed by oral itraconazole solution are licensed in the United States for this indication. Fluconazole and voriconazole have given favorable results in clinical trials of patients with low and high risk of deep mold infections, respectively. Design features that can profoundly influence outcome of empirical trials are (1) inclusion of low-risk patients, (2) failure to blind the study, (3) obscuration of antifungal effects by changing antibacterial antibiotics, (4) failure to balance both arms of the study in terms of patients with prior antifungal prophylaxis or with severe comorbidities, (5) the merging of end points evaluating safety with those of efficacy, and (6) choice of different criteria for resolution of fever.

Prolonged survival after invasive aspergillosis: a single-institution review of 11 cases

PURPOSE

To perform a retrospective review of the authors' experience with invasive aspergillosis (IA) in a pediatric population treated with conventional chemotherapy. Case series of IA in the pediatric oncology population are limited but generally report poor overall survival.

METHODS

Medical records were reviewed of all patients receiving conventional chemotherapy for malignant disease who developed IA at Children's Hospital and Regional Medical Center, Seattle, Washington, between January 1, 1995, and January 1, 2002.

RESULTS

During the study period there were 11 cases of IA in pediatric cancer patients treated with conventional chemotherapy. All patients had pulmonary IA; two also had evidence of disseminated disease. All patients underwent diagnostic tissue biopsy. Sixty-four percent required further surgery to excise bulky disease. Medical therapy varied with disease presentation and the overall clinical picture, although prolonged treatment with amphotericin B and itraconazole was the mainstay of therapy. Resolution of clinical disease was seen in 91% of patients. Seventy-three percent received further chemotherapy. The 3-year estimated survival was 82%, with a median follow-up of 32.5 months.

CONCLUSIONS

Early diagnosis and aggressive intervention improve long-term survival from IA in immunocompromised pediatric oncology patients. Aggressive surgical resection, prolonged medical therapy after gross resolution of disease, and chemoprophylaxis during subsequent chemotherapy decrease the likelihood of recurrent IA despite subsequent cytotoxic therapy. The ability to proceed with intensive chemotherapy despite a history of IA may improve long-term survival.

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.

Voriconazole: a new triazole antifungal agent

Voriconazole is a second-generation azole antifungal agent that shows excellent in vitro activity against a wide variety of yeasts and molds. It can be given by either the intravenous or the oral route; the oral formulation has excellent bioavailability. The side effect profile of voriconazole is unique in that non-sight-threatening, transient visual disturbances occur in approximately 30% of patients given the drug. Rash (which can manifest as photosensitivity) and hepatitis also occur. The potential for drug-drug interactions is high and requires that careful attention be given to dosage regimens and monitoring of serum levels and effects of interacting drugs. Voriconazole has been approved for the treatment of invasive aspergillosis and refractory infections with Pseudallescheria/Scedosporium and Fusarium species, and it will likely become the drug of choice for treatment of serious infections with those filamentous fungi.

Voriconazole: A Novel Antifungal

Objective:

To review the published in vitro, in vivo, and clinical data and FDA background documents that led to the approval of voriconazole.

Data Sources:

Articles were identified by the referenced package insert and by a MEDLINE search (1966–October 2002) using the terms voriconazole, azole antifungal, aspergillosis, and UK-109, 496. Additionally, journal Web sites and abstracts from major infectious disease meetings were researched to obtain newly published data.

Study Selection:

All animal and human data published in journals, abstracts, and FDA background documentation were used. The only in vitro susceptibility testing studies used were those that incorporated a large number of fungal isolates.

Data Synthesis:

Voriconazole is a novel monotriazole antifungal agent that inhibits the fungal cytochrome P450–mediated 14 α-lanosterol demethylation. In vitro susceptibility studies, in vivo clinical trials, and case reports have shown potent activity against various Aspergillus spp., Scedosporium, and Fusarium. Additionally, voriconazole has shown in vitro activity against dimorphic fungi and yeast, including Candida spp. and Cryptococcus neoformans. The efficacy of voriconazole has been evaluated in 4 clinical trials. The clinical studies indicate that it is at least as effective as amphotericin B for the treatment of acute invasive aspergillus infection. The most common adverse effects in clinical trials included visual disturbances, rash, and elevated liver function tests. Voriconazole is metabolized by CYP2C19, CYP2C9, and CYP3A4 and thus causes multiple serious drug–drug interactions.

Conclusions:

Voriconazole provides an advance in therapy for the treatment of acute invasive aspergillus infection.

Clinical pharmacology of antifungal compounds

Prompted by the worldwide surge in fungal infections, the past decade has witnessed a considerable expansion in antifungal drug research. New compounds have entered the clinical arena, and major progress has been made in defining paradigms of antifungal therapies. This article provides an up-to-date review on the clinical pharmacology, indications, and dosage recommendations of approved and currently investigational therapeutics for treatment of invasive fungal infections in adult and pediatric patients.

What's New in Antifungals?

The incidence of fungal infections is steadily rising. Until recently, clinicians have been limited in the number of effective antifungal agents at their disposal. Our traditional antifungal agents have either been hampered by troublesome side effects or a limited spectrum of activity. Due to the rising demand for better antifungal agents there are more agents in development than ever. Voriconazole and caspofungin are the most recent agents approved for use, offer a broad spectrum of activity, and are generally well tolerated. Several other novel agents are moving into clinical trials. A better understanding of these novel agents is critical for clinicians to effectively treat emerging fungal pathogens.

Antifungal drug resistance

The increasing incidence of invasive fungal infections is the result of many factors, including an increasing number of patients with severe immunosuppression. Although new drugs have been introduced to combat this problem, the development of resistance to antifungal drugs has become increasingly apparent, especially in patients who require long-term treatment or who are receiving antifungal prophylaxis, and there is growing awareness of shifts of flora to more-resistant species. The frequency, interpretation, and, in particular, mechanism of resistance to current classes of antifungal agents, particularly the azoles (where resistance has climbed most prominently) are discussed in this review.

Infections in Patients with Hematological Cancer: Recent Developments

One of the most common complications involved in treating patients with hematologic cancer is infection. In many cases there are multiple factors that predispose these patients to infections such as neutropenia induced by therapy or bone marrow involvement, hypogammaglobulinemia, T-cell dysfunction, and mucosal damage. In addition, newer therapies have changed the spectrum of infection that is seen in these patients.

In Section I, Dr. Blijlevens discusses mucosal damage as a major risk factor for complications of cytotoxic chemotherapy. She focuses on mucosal barrier injury (MBI) as manifest in the GI tract and will describe a pathological model to explain MBI, evaluate risk factors for development of this syndrome, explain the relationship between MBI and infection, and discuss treatment and prevention of this injury.

Invasive fungal infections continue to represent a significant problem in patients with hematologic cancer. In Section II, Drs. Anaissie and Mahfouz review the latest developments in the diagnosis, prevention, and management of invasive fungal infections with a focus on a risk-adjusted approach to this problem.

Finally, in Section III, Dr. O’Brien reviews infections associated with newer therapeutic regimens in hematologic cancers. The spectrum of infections has changed with the use of purine analogs and the advent of monoclonal antibodies. The profound T-cell suppression associated with these therapies has led to the emergence of previously rare infections such as cytomegalovirus. An approach to both prophylaxis and management of these infections is discussed.

Caspofungin acetate for treatment of invasive fungal infections

OBJECTIVE

To briefly discuss the changing epidemiology of fungal infections and review currently available agents; provide a review of caspofungin; and discuss its pharmacology, pharmacokinetics, dosing guidelines, safety and efficacy, and role in the treatment of invasive fungal infections as it relates to current antifungal therapy.

DATA SOURCES

A MEDLINE (1966 to August 2002) database search using key words caspofungin, echino candins, fungal infections, and invasive aspergillosis, was completed to identify relevant articles including reviews, recent studies, treatment guidelines, and data from Merck and Company.

STUDY SELECTION

In vitro studies and all clinical trials were evaluated to summarize the clinical efficacy and safety of caspofungin.

DATA SYNTHESIS

The incidence of fungal infections is increasing as the population at risk expands. Cost, resistance, and morbidity and mortality are key issues. Adding to the antifungal armamentarium is necessary to address these therapeutic dilemmas. Caspofungin is the first member of a new class of antifungal agents, the echinocandins, to be approved for clinical use. Caspofungin is classified as a glucan synthase inhibitor and represents a class of agents with a novel mechanism of action. Unlike currently available agents (polyenes, pyrimidines, azoles) that exert their effect on the fungal cell membrane, the echinocandins are the first agents to inhibit fungal cell wall synthesis. Caspofungin exhibits activity against Aspergillus spp. and Candida spp., including non-albicans species. Data from clinical trials demonstrate that caspofungin is effective in patients with invasive aspergillosis as well as candida esophagitis. Its Food and Drug Administration-approved indication is limited to invasive aspergillosis refractory to or intolerant of current therapy.

CONCLUSIONS

Caspofungin has activity against Aspergillus spp. as well as a variety of Candida spp. Clinical data support its usefulness in the treatment of invasive aspergillosis and select candida infections. As additional clinical data become available, it seems likely that the therapeutic role of caspofungin will expand.

Antifúngicos de uso sistémico

Invasive fungal infection is the infectious complication with highest associated mortality. Until the 90's amphotericin B was the only drug available to treat these infections. Its spectrum of antifungal activity is excellent, but its use is associated with toxicity in many cases. The development of amphotericin B lipid formulations has resulted in a significant decrease in most of the side effects associated with this drug. Triazoles are safe and effective for treating most invasive fungal infections. Fluconazole is an excellent drug for the prevention and treatment of Candida and Cryptococcus infections, itraconazole has good activity against Candida and Aspergillus, and voriconazole has shown to be better than amphotericin B for invasive aspergillosis. Caspofungin belongs to a new group of antifungal agents, the echinocandins, which are very safe and present excellent activity against Candida and Aspergillus.