Caspofungin: first approved agent in a new class of antifungals

Caspofungin (Cancidas, Merck & Co. Inc.) is the first echinocandin antifungal agent to gain FDA-approval for use in the US. It has excellent clinical activity against Candida spp. and Aspergillus spp. but lacks significant activity against Cryptococcus neoformans. Caspofungin may have some activity against dimorphic fungi such as Histoplasma capsulatum and Coccidioides immitis, but no clinical data is available for treatment of these infections. Caspofungin has demonstrated poor activity against most filamentous fungi in vitro. Several clinical trials have demonstrated its efficacy in the treatment of oropharyngeal, oesophageal and invasive candidiasis, as well as invasive aspergillosis. As a result of caspofungin's unique mechanism of action, and the high morbidity and mortality of invasive fungal infections, there is considerable interest in using this new antifungal agent as part of a combination antifungal therapy. In vitro studies and small case series indicate that caspofungin does not appear to be antagonistic when combined with other antifungals, such as itraconazole, voriconazole or amphotericin B against Aspergillus spp. Caspofungin exerts concentration-dependent killing effects in many different in vitro and animal models of disseminated fungal infection. The usual daily dose is 50 mg/day i.v. following a 70 mg i.v. loading dose. However, higher caspofungin doses have been safely administered and up to 70 mg/day can be administered for patients who fail to respond to lower doses. Caspofungin has an excellent safety profile with reduced toxicities, compared to other licensed antifungal agents. Fever, thrombophlebitis, headache and liver enzyme elevations were the most common drug-related side effects reported in clinical trials so far. Additional data are needed to document its safety in long-term use, and with higher doses in patients with invasive fungal infections. Caspofungin is a promising agent as first-line therapy for invasive candidiasis, and as salvage therapy for invasive aspergillosis. However, more clinical data are needed to define its role as primary therapy for invasive aspergillosis, and its role in combination antifungal therapy.     

Pharmacoeconomics of antifungal pharmacotherapy – challenges and future directions

The frequency and severity of invasive fungal infections have been increasingly recognised and new antifungal therapies have expanded the therapeutic armamentarium available to manage such infections. Antifungal agents comprise a significant portion of antibiotic expenditures at major medical centres, prompting adoption of cost-containment measures and treatment guidelines. This paper reviews available data regarding the costs associated with managing fungal infections, including pharmacoeconomic analyses that have been performed in the setting of documented fungal infections, as well as prophylactic and empiric use of antifungal agents. The challenges of performing such studies are discussed, as well as the limitations of published investigations. Finally, recommendations are made regarding the design and implementation of future pharmacoeconomic analyses that can help establish the true costs of managing invasive fungal infections in at-risk patient populations.     

Pharmacoeconomics of antifungal pharmacotherapy--challenges and future directions

The frequency and severity of invasive fungal infections have been increasingly recognised and new antifungal therapies have expanded the therapeutic armamentarium available to manage such infections. Antifungal agents comprise a significant portion of antibiotic expenditures at major medical centres, prompting adoption of cost-containment measures and treatment guidelines. This paper reviews available data regarding the costs associated with managing fungal infections, including pharmacoeconomic analyses that have been performed in the setting of documented fungal infections, as well as prophylactic and empiric use of antifungal agents. The challenges of performing such studies are discussed, as well as the limitations of published investigations. Finally, recommendations are made regarding the design and implementation of future pharmacoeconomic analyses that can help establish the true costs of managing invasive fungal infections in at-risk patient populations.     

Current and future antifungal therapy: new targets for antifungal therapy

Invasive fungal infections will continue to cause major complications in immunocompromized patients. At the moment, the expansion of antifungal drug research has occurred because there is a critical need for new antifungal agents to treat these life-threatening invasive fungal infections. The overview of the development of antifungal therapy which is provided here demonstrates the increased interest in this very special area of infectious diseases. Although we now have some newer and less toxic antifungal agents that are currently available for clinical use, their clinical efficacy in some invasive fungal infections, such as aspergillosis and fusariosis, is not very good. Intense efforts in antifungal drug discovery are urgently needed to develop more promising and effective antifungal agents for use in the clinical arena.     

Echinocandins: role in antifungal therapy, 2005

Novel therapies to treat invasive fungal infections have revolutionised the care of patients with candidiasis, aspergillosis and other less common fungal infections. Physicians in the twenty first century have access to safer versions of conventional drugs (i.e., lipid amphotericin B products), extended-spectrum versions of established drugs (i.e., voriconazole), as well as a new class of antifungal agents; the echinocandins. The increased number of options in the antifungal armamentarium is well timed, as the incidence of both invasive candidiasis and invasive aspergillosis, and the financial burden associated with these infections, have increased significantly in the past several decades. The increasing incidence of fungal infections has risen in parallel with the increase in critically ill and immunocompromised patients. Candida is the fourth most common bloodstream isolate, approximately 50% of which are non-albicans species. Estimates suggest there to be 9.8 episodes of invasive candidiasis per 1000 admissions to surgical intensive care units, with attributable mortality at 30% and cost per episode of US44,000 dollars. The burden of candidiasis is even higher in the paediatric population, with Candida being the second most common bloodstream infection. The increase in non-albicans candidiasis mandates the introduction of new antifungal agents capable of treating these often azole-resistant isolates. In addition, there has been a rise in the incidence of invasive aspergillosis, the most common invasive mould infection following haematopoietic stem cell transplantation, with an estimated incidence of 10 - 20%. The mortality associated with invasive aspergillosis has increased by 357% since 1980. Unfortunately, the overall survival rate among patients treated with amphotericin B, and even voriconazole, remains suboptimal, as evidenced by the failure of treatment in 47% of patients in the landmark voriconazole versus amphotericin B trial. Given the increasing incidence and suboptimal outcomes of these serious fungal infections, novel therapies represent an opportunity for significant advancement in clinical care. The current challenge is to discover the optimal place for the echinocandins in the treatment of invasive fungal infections.     

Posaconazole: a new broad-spectrum antifungal agent

The rising incidence of invasive fungal infections and the emergence of broader fungal resistance have led to the need for novel antifungal agents. Posaconazole is a new member of the triazole class of antifungals. It is available as an oral suspension and has a favorable toxicity profile, has demonstrated clinical efficacy in the treatment of oropharyngeal candidiasis and has shown promise as salvage therapy for invasive aspergillosis, zygomycosis, cryptococcal meningitis and a variety of other fungal infections. In addition, data from randomized controlled studies support its efficacy for use in prophylaxis of invasive fungal infections in patients who are severely immunocompromised. The wide spectrum activity of posaconazole in in vitro studies, animal models and preliminary clinical studies suggest that posaconazole represents an important addition to the antifungal armamentarium.     

Posaconazole: a new broad-spectrum antifungal agent

The rising incidence of invasive fungal infections and the emergence of broader fungal resistance have led to the need for novel antifungal agents. Posaconazole is a new member of the triazole class of antifungals. It is available as an oral suspension and has a favorable toxicity profile, has demonstrated clinical efficacy in the treatment of oropharyngeal candidiasis and has shown promise as salvage therapy for invasive aspergillosis, zygomycosis, cryptococcal meningitis and a variety of other fungal infections. In addition, data from randomized controlled studies support its efficacy for use in prophylaxis of invasive fungal infections in patients who are severely immunocompromised. The wide spectrum activity of posaconazole in in vitro studies, animal models and preliminary clinical studies suggest that posaconazole represents an important addition to the antifungal armamentarium.     

The echinocandins: three useful choices or three too many?

Echinocandins act by inhibiting 1,3-β-d-glucan synthesis in the fungal cell wall. The three licensed agents in this class, namely anidulafungin, caspofungin and micafungin, have a favourable pharmacological profile. These agents are narrow spectrum with clinically relevant activity against Candida and Aspergillus spp. Several trials have established the non-inferiority of these agents over existing agents in the treatment of invasive fungal infections. Caspofungin is also licensed for empirical antifungal therapy of presumed fungal infections in patients with febrile neutropenia. This paper reviews the literature on echinocandins.     

Review of the safety,tolerability, and drug interactions of the new antifungal agents caspofungin and voriconazole

Managing invasive fungal infections often presents a challenge for clinicians in the treatment of immunocompromised patients. Two very different systemic antifungal agents, voriconazole and caspofungin, have recently been introduced into the market place. Voriconazole is a new triazole antifungal, while caspofungin is the first echinocandin antifungal. Voriconazole acts by inhibiting the synthesis of ergosterol in the fungal cell membrane. Caspofungin inhibits beta-1,3-D-glucan synthesis in the cell wall, a target present in fungal cells, but absent from mammalian cells. Both agents are broad-spectrum, with efficacy against invasive Aspergillus and Candida infections. The safety and tolerability profile of caspofungin presented with a low incidence of adverse events in clinical trials. Pending further data, coadministration of cyclosporine has been recommended only if the benefit outweighs the risk for patients. Voriconazole has three important side-effects that the clinician must consider: liver abnormalities, skin abnormalities and visual disturbances. Liver abnormalities in particular should be monitored very carefully. The drug interaction profile of voriconazole also warrants a careful evaluation of the concomitant medication, mainly due to cytochrome P450 metabolism. This article reviews the available data concerning the safety and tolerability profiles of each drug, as well as drug interactions and contraindications.     

Anidulafungin,a new antifungal drug

ObjectivesThe development of new antifungal drugs has become a challenge for pharmaceutical industry due to the increasing incidence of invasive fungal infections.MethodsExperience of existing antifungal drugs has shown that, like in bacteria against antibiotics, most fungal species, especially in Candida spp, resistance to previously active drugs is developing and constitutes a major problem in treating invasive fungal infections.ResultsAmong series of newer drugs, experimental data and literature search have unravelled a new class of antifungals, Echinocandins which inhibit successfully Candida spp resistant to other drugs such as fluconazole. One drug, anidulafungin has emerged recently in this class as one of the most active in invasive fungal infections.     

Novel triazole antifungal agents

The risk of opportunistic infections is greatly increased in patients who are immunocompromised due to AIDS, cancer chemotherapy and organ or bone marrow transplantation. Candida albicans is often associated with serious systemic fungal infections, however other Candida species such as Candida krusei, Candida tropicalis and Candida glabrata, as well as Cryptococcus neoformans and filamentous fungi such as Aspergillus, have also emerged as clinically significant fungal pathogens. Two triazole antifungal agents, fluconazole and itraconazole, were introduced over a decade ago and since then have been used extensively for the prophylaxis and treatment of a variety of fungal infections. Although both drugs are effective and have their place in therapy, limitations regarding the utility of these agents do exist. For example, fluconazole is not effective for the prophylaxis or treatment of Aspergillus species and has limited activity against C. krusei and C. glabrata. The use of itraconazole has been limited secondary to concerns regarding unpredictable bioavailability. The rising incidence of fungal infections and the reported increase of non-albicans candidal infections noted over the past two decades highlight the need for new antifungal agents with improved spectra of activity. Several new triazole agents are in various phases of preclinical and clinical trials and may be available for human use in the near future. Three such agents voriconazole, posaconazole and ravuconazole are reviewed and compared with existing agents.     

Novel triazole antifungal agents

The risk of opportunistic infections is greatly increased in patients who are immunocompromised due to AIDS, cancer chemotherapy and organ or bone marrow transplantation. Candida albicans is often associated with serious systemic fungal infections, however other Candida species such as Candida krusei, Candida tropicalis and Candida glabrata, as well as Cryptococcus neoformans and filamentous fungi such as Aspergillus, have also emerged as clinically significant fungal pathogens. Two triazole antifungal agents, fluconazole and itraconazole, were introduced over a decade ago and since then have been used extensively for the prophylaxis and treatment of a variety of fungal infections. Although both drugs are effective and have their place in therapy, limitations regarding the utility of these agents do exist. For example, fluconazole is not effective for the prophylaxis or treatment of Aspergillus species and has limited activity against C. krusei and C. glabrata. The use of itraconazole has been limited secondary to concerns regarding unpredictable bioavailability. The rising incidence of fungal infections and the reported increase of non-albicans candidal infections noted over the past two decades highlight the need for new antifungal agents with improved spectra of activity. Several new triazole agents are in various phases of preclinical and clinical trials and may be available for human use in the near future. Three such agents voriconazole, posaconazole and ravuconazole are reviewed and compared with existing agents.     

A comprehensive review on potential applications of metallic nanoparticles as antifungal therapies to combat human fungal diseases

Human pathogenic fungi are responsible for causing a range of infection types including mucosal, skin, and invasive infections. Life-threatening and invasive fungal infections (FIs) are responsible for mortality and morbidity, especially for individuals with compromised immune function. The number of currently available therapeutic agents against invasive FIs is limited compared to that against bacterial infections. In addition, the increased mortality and morbidity caused by FIs are linked to the limited number of available antifungal agents, antifungal resistance, and the increased toxicity of these agents. Currently available antifungal agents have several drawbacks in efficiency, efficacy, toxicity, activity spectrum, and selectivity. It has already been demonstrated with numerous metallic nanoparticles (MNPs) that these nanoparticles can serve as an effective and alternative solution as fungicidal agents. MNPs have great potential owing to their intrinsic antifungal properties and potential to deliver antifungal drugs. For instance, gold nanoparticles (AuNPs) have the capacity to disturb mitochondrial calcium homeostasis induced AuNP-mediated cell death in Candida albicans. In addition, both copper nanoparticles and copper oxide nanoparticles exerted significant suppressive properties against pathogenic fungi. Silver nanoparticles showed strong antifungal properties against numerous pathogenic fungi, such as Stachybotrys chartarum, Mortierella alpina, Chaetomium globosum, A. fumigatus, Cladosporium cladosporioides, Penicillium brevicompactum, Trichophyton rubrum, C. tropicalis, and C. albicans. Iron oxide nanoparticles showed potent antifungal activities against A. niger and P. chrysogenum. It has also been reported that zinc oxide nanoparticles can significantly inhibit fungal growth. These NPs have already exerted potent antifungal properties against a number of pathogenic fungal species including Candida, Aspergillus, Fusarium, and many others. Several strategies are currently used for the research and development of antifungal NPs including chemical modification of NPs and combination with the available drugs. This review has comprehensively presented the current and innovative antifungal approach using MNPs. Moreover, different types of MNPs, their physicochemical characteristics, and production techniques have been summarized in this review.     

Review of the safety,tolerability, and drug interactions of the new antifungal agents caspofungin and voriconazole

SUMMARY

Managing invasive fungal infections often presents a challenge for clinicians in the treatment of immunocompromised patients. Two very different systemic antifungal agents, voriconazole and caspofungin, have recently been introduced into the market place. Voriconazole is a new triazole antifungal, while caspofungin is the first echinocandin antifungal. Voriconazole acts by inhibiting the synthesis of ergosterol in the fungal cell membrane. Caspofungin inhibits β-1,3-D-glucan synthesis in the cell wall, a target present in fungal cells, but absent from mammalian cells. Both agents are broad-spectrum, with efficacy against invasive Aspergillus and Candida infections. The safety and tolerability profile of caspofungin presented with a low incidence of adverse events in clinical trials. Pending further data, coadministration of cyclosporine has been recommended only if the benefit outweighs the risk for patients. Voriconazole has three important side-effects that the clinician must consider: liver abnormalities, skin abnormalities and visual disturbances. Liver abnormalities in particular should be monitored very carefully. The drug interaction profile of voriconazole also warrants a careful evaluation of the concomitant medication, mainly due to cytochrome P450 metabolism. This article reviews the available data concerning the safety and tolerability profiles of each drug, as well as drug interactions and contraindications.     

Recent advances and challenges in the treatment of invasive fungal infections

The frequency of invasive fungal infections (IFIs) has increased over the last decade with the rise in at-risk populations of patients. The morbidity and mortality of IFIs are high and management of these conditions is a great challenge. With the widespread adoption of antifungal prophylaxis, the epidemiology of invasive fungal pathogens has changed. Non-albicans Candida, non-fumigatus Aspergillus and moulds other than Aspergillus have become increasingly recognised causes of invasive diseases. These emerging fungi are characterised by resistance or lower susceptibility to standard antifungal agents. Invasive infections due to these previously rare fungi are therefore more difficult to treat. Recently developed antifungal agents provide the potential to improve management options and therapeutic outcomes of these infections. The availability of more potent and less toxic antifungal agents, such as second-generation triazoles and echinocandins, has led to considerable improvement in the treatment of IFIs. This article reviews the changing spectrum of invasive mycosis, the properties of recently developed antifungal agents and their role in the management of these infections.     

Posaconazole

Invasive fungal infections are occurring with increasing frequency secondary to medical advances in the areas of transplantation, cancer management and autoimmune diseases. Unfortunately, the currently available antifungal armamentarium does not meet the increasing needs of managing infection in these complex patient populations. Posaconazole, a new triazole antifungal agent, is being investigated for its role in treating serious infections due to yeasts and molds. This new drug offers an expanded spectrum of activity over other members of its class. In addition to potent activity against fluconazole-resistant Candida and refractory cases of aspergillosis, posaconazole demonstrates activity against Zygomycetes. Posaconazole is a well-tolerated agent that offers a diminished toxicity profile compared with other currently marketed systemic antifungal agents. Clinical success rates thus far have been promising, although the exact role of this agent in treating and preventing invasive fungal infections is yet to be determined.     

Systemic antifungal agents against AIDS-related opportunistic infections: current status and emerging drugs in development.

No effective drug was available for the treatment of systemic fungal infections until the discovery of Amphotericin B in 1953. Since then flucytosine, azoles and later the triazoles, have now become available. The current interest in the development of new antifungal agents can partially be explained by the dramatic rise in the number of AIDS cases and the subsequent suppression of the immune system in patients with the disease. For example, over 90% of those diagnosed to be HIV-positive contract a fungal infection during the course of their illness. Other conditions that have spurred the development of new systemic antifungal agents include the increase in the frequency of bone marrow and organ transplants, the use of antineoplastic agents, long-term use of corticosteroids and even the indiscriminate use of antibiotics. The emergence of fungi resistant to currently available agents, especially the azoles, has made the need for new and effective antifungal agents more urgent. This review article focuses on agents targeted against opportunistic fungal infections, i.e., fungal infections which, in contrast to immunocompetent individuals, may cause serious life-threatening illness in immunocompromised individuals. Agents currently on the market or undergoing clinical development, as well as potential new agents that have been discovered, are discussed.     

Amphotericin B lipid complex in the management of invasive fungal infections in immunocompromised patients

Invasive fungal infections are associated with a poor outcome and their incidence is rising. Amphotericin B has for a long time been the gold standard for treatment of these infections, but the conventional formulation is associated with a high incidence of adverse events. Lipid formulations of amphotericin, developed to overcome these drawbacks, are now routinely used in clinical practice for the treatment of invasive fungal infections in immunocompromised patients. Amphotericin B lipid complex (ABLC) is prepared from amphotericin complexed to two phospholipids, a process that confers a number of important pharmacodynamic and pharmacokinetic properties compared with conventional amphotericin B. The results of retrospective observational studies and the analysis of databases, including the large Collaborative Exchange of Antifungal Research (CLEAR) database, have shown ABLC to be associated with response rates of up to about 80% in patients with confirmed fungal infections and around 60% in those treated empirically. Intranasal administration of ABLC for prophylaxis of invasive fungal infection in immunocompromised patients is safe and appears to be a promising treatment strategy for the future. ABLC is associated with a substantially lower incidence of nephrotoxicity than conventional amphotericin. Infusion-related reactions also occur less frequently than with conventional amphotericin and can be managed using premedication protocols. When direct and indirect costs are measured, ABLC appears to be less expensive than conventional amphotericin. The number of approved antifungal agents that are effective treatments for invasive fungal infections is increasing. However, lipid formulations of amphotericin, such as ABLC, are effective and well tolerated and remain the standard of care in the treatment of invasive fungal infections. Treatment strategies such as intranasal administration for prophylaxis and combination therapy with newer agents are future directions for these agents.     

A review of the new antifungals: posaconazole, micafungin, and anidulafungin

This column reviews 3 new systemic antifungal agents (posaconazole, micafungin, and anidulafungin) from the standpoint of dermatology. Posaconazole, approved to treat invasive Aspergillus and Candida infections, is available in an oral suspension and resembles fluconazole, but seems to have a broader spectrum of activity. Posaconazole is effective against yeasts and molds and could be effective in treating rare fungal infections involving Zygomycetes, Mucor necrotizing fasciitis, rhinocerebral mucormycosis, some Fusarium species, Penicillium, Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, and sporotrichosis, chromoblastomycosis, mycetoma, and phaeohyphomycosis, including Scedosporium apiospermum and Exophiala, Alternaria, and Bipolaris species. Posaconazole may abate onychomycosis and dermatophytes, but clinical trial data is lacking. Micafungin and anidulafungin are echinocandins like caspofungin and are useful salvage therapy for invasive aspergillosis and candidiasis. The exciting new agents have extended the armamentarium against antifungal pathogens, but have yet to find their place in the dermatologic practice.     

Antifungal treatment in pediatric patients.

Invasive fungal infections have increased in frequency and severity over the past two decades as a result of an increasing number of immunocompromised patients. This new age of opportunistic fungal infections extends to pediatric patients. The last decade has seen the development of several new antifungal agents for the treatment of these infections. However, there is a paucity of data on the treatment of invasive fungal infections in children. This review provides a brief overview of the current state of antifungal therapy for children, discussing the important antifungal classes and the differences in mechanisms of action and resistance, pharmacology, and efficacy and safety data in pediatric patients outside the neonatal period.