Use of azoles for systemic antifungal therapy

Multi-Omics Analysis of Lipid Metabolism for a Marine Probiotic Meyerozyma guilliermondii GXDK6 Under High NaCl Stress

Investigating microbial lipid regulation contributes to understanding the lipid-dependent signal transduction process of cells and helps to improve the sensitivity of microorganisms to environmental factors by interfering with lipid metabolism, thus beneficial for constructing advanced cell factories of novel molecular drugs. Integrated omics technology was used to systematically reveal the lipid metabolism mechanism of a marine Meyerozyma guilliermondii GXDK6 under high NaCl stress and test the sensitivity of GXDK6 to antibiotics when its lipid metabolism transformed. The omics data showed that when GXDK6 perceived 10% NaCl stress, the expression of AYR1 and NADPH-dependent 1-acyldihydroxyacetone phosphate reductase was inhibited, which weaken the budding and proliferation of cell membranes. This finding was further validated by decreased 64.39% of OD₆₀₀ under 10% NaCl stress when compared with salt-free stress. In addition, salt stress promoted a large intracellular accumulation of glycerol, which was also verified by exogenous addition of glycerol. Moreover, NaCl stress remarkably inhibited the expression of drug target proteins (such as lanosterol 14-alpha demethylase), thereby increasing sensitivity to fluconazole. This study provided new insights into the molecular mechanism involved in the regulation of lipid metabolism in Meyerozyma guilliermondii strain and contributed to developing new methods to improve the effectiveness of killing fungi with lower antibiotics.

Review of Pharmacologic Considerations in the Use of Azole Antifungals in Lung Transplant Recipients

Mold-active azole antifungals are commonly prescribed for the prevention of invasive fungal infections in lung transplant recipients. Each agent exhibits a unique pharmacologic profile, an understanding of which is crucial for therapy selection and optimization. This article reviews pharmacologic considerations for three frequently-used azole antifungals in lung transplant recipients: voriconazole, posaconazole, and isavuconazole. Focus is drawn to analysis of drug-interactions, adverse drug reactions, pharmacokinetic considerations, and the role of therapeutic drug monitoring with special emphasis on data from the post-lung transplant population.

Antifungal activity of enynediesters and acetylenic compounds obtained by synthesis and in silico prediction pattern

OBJECTIVE

In this paper, we describe the preparation and synthesis of several enynediesters, conjugated diynes and acetylenic compounds from starting materials comprising one hydroxyl and one acetylenyl group and their antifungal activity.

MATERIALS AND METHODS

For synthesis of the compounds, a combined solution of N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridin in CH2Cl2 was added to a solution of compound containing one hydroxyl group and propiolic acid at 0°C over a period of 1 hour. As the reaction occurs under very mild conditions this procedure offers easy access to 1,3-diynes in a very short reaction time. Some of the compounds are commercially available. The antifungal activity of these compounds against Candida albicans, Aspergillus niger and Saccharomyces cerevisiae was investigated.

RESULTS

Among the compounds tested, some showed potent activity.

CONCLUSION

The results of synthesis showed that the direct coupling of two acetylenes is suitable for the preparation of diynes. The in silico study used here was able to predict if the compound with triple bond can posses the antifungal activity with a reasonable prediction. The result of investigations at both in silico and in vitro levels confirmed that the position of the triple bond is important for antifungal activity.

Intensive care unit-related fluconazole use in Spain and Germany: patient characteristics and outcomes of a prospective multicenter longitudinal observational study

BACKGROUND

Candida spp. are a frequent cause of nosocomial bloodstream infections worldwide.

OBJECTIVE

To evaluate the use patterns and outcomes associated with intravenous (IV) fluconazole therapy in intensive care units in Spain and Germany.

PATIENTS AND METHODS

The research reported here was a prospective multicenter longitudinal observational study in adult intensive care unit patients receiving IV fluconazole. Demographic, microbiologic, therapy success, length of hospital stay, adverse event, and all-cause mortality data were collected at 14 sites in Spain and five in Germany, from February 2004 to November 2005.

RESULTS

Patients (n = 303) received prophylaxis (n = 29), empiric therapy (n = 140), preemptive therapy (n = 85), or definitive therapy (n = 49). A total of 298 patients (98.4%) were treated with IV fluconazole as first-line therapy. The treating physicians judged therapy successful in 66% of prophylactic, 55% of empiric, 45% of preemptive, and 43% of definitive group patients. In the subgroup of 152 patients with proven and specified Candida infection only, 32% suffered from Candida specified as potentially resistant to IV fluconazole. The overall mortality rate was 42%.

CONCLUSION

Our study informs treatment decision makers that approximately 32% of the patients with microbiological results available suffered from Candida specified as potentially resistant to IV fluconazole, highlighting the importance of appropriate therapy.

Hydrogel of ketoconazole and PAMAM dendrimers: formulation and antifungal activity

Ketoconazole (KET), an imidazole derivative with well-known antifungal properties, is lipophilic and practically insoluble in water, therefore its clinical use has some practical disadvantages. The aim of the present study was to investigate the influence of PAMAM-NH₂ and PAMAM-OH dendrimers generation 2 and generation 3 on the solubility and antifungal activity of KET and to design and evaluate KET hydrogel with PAMAM dendrimers. It was shown that the surface charge of PAMAM dendrimers strongly affects their influence on the improvement of solubility and antifungal activity of KET. The MIC and MFC values obtained by broth dilution method indicate that PAMAM-NH₂ dendrimers significantly (up to 16-fold) increased the antifungal activity of KET against Candida strains (e.g., in culture Candida albicans 1103059/11 MIC value was 0.008 μg/mL and 0.064 μg/mL, and MFC was 2 μg/mL and 32 μg/mL for KET in 10 mg/mL solution of PAMAM-NH₂ G2 and pure KET, respectively). Antifungal activity of designed KET hydrogel with PAMAM-NH₂ dendrimers measured by the plate diffusion method was definitely higher than pure KET hydrogel and than commercial available product. It was shown that the improvement of solubility and in the consequence the higher KET release from hydrogels seems to be a very significant factor affecting antifungal activity of KET in hydrogels containing PAMAM dendrimers.

Use of amphotericin B lipid complex in elderly patients

OBJECTIVES

The safety and effectiveness of amphotericin B lipid complex (ABLC) treatment in elderly patients was investigated using a large multicenter database.

METHODS

Data analysis was conducted on retrospectively collected patient data from 572 patients >65 years of age and 2930 patients < or =65 years of age treated for fungal infections at 160 North American hospitals.

RESULTS

Patients were typically treated with ABLC for Candidiasis, multiple fungal pathogen infections and Aspergillosis, or were treated empirically. The median cumulative dose of ABLC in patients >65 years of age and those 65 years of age was similar (3000 and 3258 mg, respectively, P=0.127). Despite higher median pretreatment serum creatinine (S-Cr) among patients >65 years of age (1.7 mg/dl vs. 1.4 mg/dl, respectively), both groups showed only a 0.1mg/dl median S-Cr change from baseline by the end of therapy (P=0.525). Clinical response was 56 and 51%, respectively, in patients >65 years of age and patients 65 years of age or younger (P=0.049).

CONCLUSIONS

This study suggests that ABLC can be safely and effectively used in the treatment of invasive fungal disease in elderly patients.

Importance of antifungal drug-resistance: clinical significance and need for novel therapy

The incidence of fungal infections has increased dramatically over the past few decades due to the increase in the members of the population susceptible to such infections. This population includes individuals undergoing chemotherapy for cancer, those enduring long-term treatment with antibacterial agents, those receiving immunosuppressive drugs following transplantations, or those immunosuppressed due to diseases, such as AIDS, or malignancies. Newer antifungal agents, namely the triazoles, have aided in both the treatment of fungal infections and in the prevention of disease in susceptible individuals. However, resistance to the azoles, as well as to the polyenes, has resulted in clinical failures. Only a few potential antifungal targets have been exploited to date and there is a critical need for the discovery and development of novel antifungal agents that will result in improved therapy in this ever-expanding patient population. An increased intensity in the study of fungal pathogens at the molecular level holds the key to such advances.

Effects of topical amphotericin B on expression of cytokines in nasal polyps

OBJECTIVE

Although chronic rhinosinusitis (CRS) is one of the most frequently reported chronic diseases its etiology is not well understood. Recently, fungi have been proposed to influence the chronicity of rhinosinusitis. If fungi do play an important role then topical antifungal treatment may improve the inflammatory process of CRS. Therefore, in this study we measured inflammatory cytokine levels in nasal polyps after intranasal antifungal irrigation.

MATERIAL AND METHODS

Nasal polyps were collected before and 4 weeks after treatment with 100 mg/l topical amphotericin B (n = 16), 50 mg/l topical amphotericin B (n = 14) or normal saline (n = 11). The cytokine--IL-5, IL-8, interferon-gamma, RANTES--protein content of polyp homogenates were determined by means of ELISA.

RESULTS

Nasal polyps were found to contain large amounts of cytokines (IL-5, IL-8 and RANTES) compared with normal inferior turbinates. After 4 weeks of treatment with topical agents, IL-5 levels tended to decrease in comparison with those of the other cytokines, but this difference was not statistically significant.

CONCLUSIONS

Topical amphotericin B treatment and nasal saline irrigation both influence the expression of nasal polyp cytokines. Topical nasal irrigation may influence the inflammatory process of CRS.

Structure and Generation Mechanism of a Novel Degradation Product Formed by Oxidatively Induced Coupling of Miconazole Nitrate with Butylated Hydroxytoluene in a Topical Ointment Studied by HPLC-ESI-MS and Organic Synthesis

In a petrolatum based topical ointment formulation containing miconazole nitrate (1) as the active ingredient and 2,6-di-t-butyl-4-methylphenol (BHT) as a vehicle antioxidant, an oxidatively induced coupling reaction between miconazole nitrate and BHT occurred to form a novel adduct 1-(3,5-di-tert-butyl-4-hydroxy-benzyl)-3-[2-(2,4-dichloro-benzyloxy)-2-(2,4-dichloro-phenyl)-ethyl]-3H-imidazol-1-ium nitrate (2). The structure of 2 was established using high-performance liquid chromatography coupled with electrospray ionization mass spectrometry and was confirmed by comparing with a synthesized reference compound. The reaction proceeded through a quinone methide intermediate from BHT. Two synthetic methods were established for preparing 2.

Disseminated aspergillosis due to Aspergillus flavus in an experimental model: efficacy of azole therapy

The aim of this investigation was to create a reproducible experimental model of disseminated Aspergillus flavus aspergillosis, and to compare the relative therapeutic efficacies of itraconazole and fluconazole in this model. Temporarily immunosuppressed male Wistar rats received intravenous challenge by A. flavus conidia. Treatment was initiated 24 h later with oral itraconazole (1 mg kg-1 BW day-1), oral fluconazole (1 mg kg-1 BW day-1) or excipient only (infected-untreated rats); this was continued for 10 days. At this time, although 100% mortality had occurred among all infected-untreated rats, no mortality was noted among the control-uninfected, infected-itraconazole-treated or infected-fluconazole-treated rats. After killing, essential organs were processed for microbiological and histopathological studies. Aspergillus flavus was recovered in high colony counts from the organs of infected-untreated rats (lungs > liver > brain > kidneys), but in significantly lower colony counts, or not at all, from the organs of itraconazole-treated and fluconazole-treated rats. Histopathological alterations were pronounced in tissues of infected-untreated rats, but less so in treated rats. These data suggest that administration of itraconazole or fluconazole sufficiently early may prevent, or retard, progression of lesions in disseminated aspergillosis.

Management of histoplasmosis

Histoplasmosis is a systemic fungal infection that infects millions of people living in areas where the infection is endemic. However, most people with histoplasmosis have a self-limited illness that does not require treatment with an antifungal agent. Patients who do require treatment are those who are immunosuppressed, those who are exposed to a large fungal inoculum that overwhelms their immune system, and those who have symptomatic disseminated infection, chronic pulmonary infection, or focal organ involvement. The treatment of choice for severe histoplasmosis is amphotericin B, while itraconazole is given for mild to moderate histoplasmosis. Most patients who require initial treatment with amphotericin B respond quickly and can then be switched to itraconazole to finish the course of therapy.

Candida: a causative agent of an emerging infection

Incidences of infections due to Candida have increased over the last 15-20 y. This increase in the incidence and the high associated mortality rate despite therapy has focused the attention on this disease and prompted investigators to undertake research aimed at understanding the pathogenesis of this disease as well as methods to treat it. This paper discusses recent developments in the Candida field and the impact they have on patient management.

Treatment of systemic fungal infections in older patients: achieving optimal outcomes

Systemic fungal infections are an increasing problem in older adults. For several of the endemic mycoses, this increase is the result of increased travel and leisure activities in areas endemic for these fungi. Immunosuppressive agents, care in an intensive care unit, and invasive devices all contribute to infection with opportunistic fungi. Treatment of systemic fungal infections is usually with an azole or amphotericin B. The preferred regimen depends on the specific fungal infection, the site and the severity of the infection, the state of immunosuppression of the patient and the possible toxicities of each drug for a specific patient. In older adults, drug-drug interactions between the azoles and drugs commonly prescribed for older persons may lead to serious toxicity, and absorption of itraconazole can be problematic. Amphotericin B is associated with significant nephrotoxicity, especially in older adults with pre-existing renal disease, and infusion-related adverse effects. Newer lipid formulations of amphotericin B can obviate some of these toxicities, but their role in the treatment of systemic fungal infections in older adults has not yet been clarified.

Fungal infections in older adults

Invasive fungal infections have become an increasing problem in older adults. Infections with opportunistic fungi have increased because older patients are more likely to be considered for transplantation, receive aggressive regimens of chemotherapy for cancer, and take immunosuppressive drugs for nonmalignant diseases. In addition, healthy older adults are now more likely to travel extensively and to indulge in outdoor activities, which put them at risk for exposure to endemic mycoses. Although many of the clinical manifestations of fungal infections in older and younger adults are similar, there are aspects of histoplasmosis, aspergillosis, and cryptococcosis that are unique to older patients. Treatment of older adults with amphotericin B is difficult because of the intrinsic nephrotoxicity of the drug. Although they are less toxic, azoles must be used carefully for treatment of older adults, who are more likely to experience serious drug-drug interactions than are younger persons.

New developments in chemotherapy for non-invasive fungal infections

Dermatomycosis and subcutaneous mycosis comprise the non-invasive fungal infections commonly encountered in clinical practice around the world. The limited activity of early topical antifungal agents prompted the development of more effective systemic agents. While griseofulvin has been used for more than four decades, the use of early azoles, such as ketoconazole have resulted in better patient compliance and thus greater success. However, poor response and recurrence in dermatomycosis, as well as toxicity associated with ketoconazole therapy, has led to the search for newer antifungal agents and more effective treatment strategies. Terbinafine, itraconazole and fluconazole have the advantage of non-toxicity and a broad spectrum of activity. An overview of non-invasive fungal infections, antifungal agents in clinical use and recent developments in antifungal therapy is reviewed in this article.

Intravenous itraconazole

OBJECTIVE

To review the pharmacology, mycology, chemistry, pharmacokinetics, efficacy, safety, tolerability, dosage, administration, and economic issues of intravenous itraconazole.

DATA SOURCES

A MEDLINE search from 1978 to June 2000 of the English-language literature and an extensive review of meeting abstracts was conducted. Due to the paucity of published information concerning the pharmacokinetics, efficacy, and safety of the intravenous formulation of intravenous itraconazole, additional information was obtained from the manufacturer.

DATA EXTRACTION

Data from in vitro and preclinical studies, as well as Phase II and III clinical trials, were included.

DATA SYNTHESIS

The triazole antifungal agent itraconazole is available in a cyclodextrin-based intravenous formulation. Intravenous itraconazole is indicated for the treatment of pulmonary and extrapulmonary blastomycosis; histoplasmosis, including chronic cavitary pulmonary disease and disseminated, nonmeningeal histoplasmosis; and pulmonary and extrapulmonary aspergillosis in patients who are intolerant of or who are refractory to amphotericin B. This formulation provides quicker and more consistent therapeutic concentrations than the oral formulations. Clinical data comparing the efficacy of intravenous itraconazole with that of amphotericin B are lacking.

CONCLUSIONS

Intravenous itraconazole offers a less toxic alternative for patients with pulmonary and extrapulmonary blastomycosis, histoplasmosis, and aspergillosis who cannot receive oral medications or who are intolerant of or refractory to amphotericin B.

New investigational antifungal agents for treating invasive fungal infections

Systemic fungal infections have been recognised as a major cause of morbidity and mortality during the last two decades. There are only a few therapeutic options for these infections. Severe toxicity, such as impairment of renal function, limits the use of amphotericin B. Flucytosine is associated with side effects and drug resistance. Fluconazole and itraconazole are safer, though emergence of resistance and innate resistance in some fungal pathogens is a concern in their use. Therefore, there is a need for developing novel drugs and/or treatment strategies to combat these infections. In recent years, increased efforts by the pharmaceutical industry and academia have led to the discovery of new re-engineered or reconsidered antifungal agents that are more efficacious, safer and have a broad spectrum of activity. Lipid formulations of polyene antifungal agents, amphotericin B and nystatin, have the advantage of improved therapeutic index. Activity against resistant fungi, high bioavailability, safety and longer half-life are the properties that encourage development of the newer triazoles (e.g., voriconazole, ravuconazole and posaconazole). Echinocandin-like lipopeptide antibiotics are among the antifungal agents with a novel mode of action. In addition to these lead investigational compounds, development of newer antifungal agents is underway.

Use of antifungal drugs in pregnancy: a focus on safety

The use of antifungals in pregnancy requires special consideration for the safety of the developing fetus. Clinicians now have an increased repertoire of both topical and systemic antimycotics available to treat superficial or mucotaneous fungal infections including Candida vaginitis. The ability of many nontopical antifungals to penetrate the placenta and achieve measurable, often therapeutic, concentrations in cord blood, fetal tissue and amniotic fluid means that evidence exists of successful treatment of all varieties of systemic fungal disease in pregnant women, even with placental involvement. However, for the same reasons, safety considerations remain a concern. Although the use of azoles as topical agents for superficial infections is both efficacious and well tolerated, especially when used for short periods, systemic azole therapy is not recommended in pregnancy. Accordingly, amphotericin B remains the drug of choice for systemic, invasive mycotic infections, whether life-threatening or less severe. Unfortunately little if any information is available regarding the safety of the newer lipid formulations of amphotericin B. There is a general reluctance to perform randomised, comparative studies involving antifungal agents in pregnancy, hence cumulative anecdotal reports form much of the available data; animal studies, although useful, have several drawbacks. There is a need for additional safe and effective new antifungal agents for widespread use in pregnant women.

Agents for treatment of invasive fungal infections

The incidence of fungal infections continues to rise as the population of immunocompromised individuals increases. Despite the enlarging numbers of infections, there are only a few antifungal agents for treatment of deep-seated, invasive infections. These agents include amphotericin B, flucytosine, terbinafine, and several azoles. Progress has been made in understanding the role of these agents in a variety of infections and this article examines in detail these agents and their prophylactic, empiric, and therapeutic uses in invasive mycoses. This article focuses on general concepts of antifungal therapies and provides a detailed review of each antifungal agent available for treatment of deep-seated mycoses.

Prevention and prophylaxis of invasive fungal sinusitis in the immunocompromised patient

Fungal infections are a leading cause of morbidity and mortality among immunocompromised patients. Invasive fungal sinusitis is a devastating complication of immunosuppression. Treatment options are limited and often ineffective, making prevention important. Measures to decrease environmental exposure, indications for antifungal prophylaxis, and limitations of current regimens are discussed.