Antifungal agents used for deep-seated mycotic infections

Membrane Sterols Modulate the Binding Mode of Amphotericin B without Affecting Its Affinity for a Lipid Bilayer

Membrane-active antibiotics are known to selectively target certain pathogens based on cell membrane properties, such as fluidity, lipid ordering, and phase behavior. These are in turn modulated by the composition of a lipid bilayer and in particular by the presence and type of membrane sterols. Amphotericin B (AmB), the golden standard of antifungal treatment, exhibits higher activity toward ergosterol-rich fungal membranes, which permits its use against systemic mycoses; however, the selectivity for fungal membranes is far from satisfactory leading to severe side effects. Despite decades of research, no consensus has emerged on the origin of AmB specificity for fungal cells and its actual mode of action at the molecular level. Previously, it has been proposed that the specific action of AmB is related to differences in its affinity for membranes of different composition. In this work, we investigate this relationship by employing molecular dynamics simulations to compare the free energy of insertion of AmB into three types of membranes: a pure DMPC bilayer and DMPC bilayers containing 30% of cholesterol or ergosterol. We analyze the orientation of AmB molecules within the bilayer in order to unambiguously establish their membrane binding mode and relate the orientational freedom to the sterol-dependent tightness of lipid packing. Our results strongly indicate that the membrane insertion of AmB proceeds virtually to completion independent of membrane type, and hence the higher toxicity against fungal membranes may rather result from differences in subsequent oligomerization in the membrane and assembly of monomers into functional transmembrane pores. In particular, the latter could be facilitated by sterol-induced ordering of AmB molecules along the membrane normal, revealed by our free energy profiles. Moreover--in contrast to certain claims--we find no stable binding mode corresponding to the horizontal adsorption of AmB on the membrane surface.

Innovation of natural essential oil-loaded Orabase for local treatment of oral candidiasis

PURPOSE

Oral candidiasis may be manifested in the oral cavity as either mild or severe oral fungal infection. This infection results from the overgrowth of Candida species normally existing in the oral cavity in minute amounts based on many predisposing factors. Several aspects have spurred the search for new strategies in the treatment of oral candidiasis, among which are the limited numbers of new antifungal drugs developed in recent years. Previous studies have shown that thyme and clove oils have antimycotic activities and have suggested their incorporation into pharmaceutical preparations. This study aimed to investigate the possibility of the incorporation and characterization of essential oils or their extracted active ingredients in Orabase formulations.

METHODS

Orabase loaded with clove oil, thyme oil, eugenol, and thymol were prepared and evaluated for their antifungal activities, pH, viscosity, erosion and water uptake characteristics, mechanical properties, in vitro release behavior, and ex vivo mucoadhesion properties.

RESULTS

All prepared bases showed considerable antifungal activity and acceptable physical characteristics. The release pattern from loaded bases was considerably slow for all oils and active ingredients. All bases showed appreciable adhesion in the in vitro and ex vivo studies.

CONCLUSION

The incorporation of essential oils in Orabase could help in future drug delivery design, with promising outcomes on patients' well-being.

Candida esophagitis in an immunocompetent pregnant woman

Background: Nausea and vomiting are common during the first half of pregnancy and usually require only supportive measures. When symptoms are progressive and weight loss occurs, treatable causes should be sought by means of upper gastrointestinal endoscopy. We report a case of an immunocompetent gravida with invasive Candida albicans esophagitis.

Case: The immunocompetent primigravida developed progressive nausea, vomiting, epigastric pain, and a 4.1 kg weight loss during the second trimester of pregnancy. Treatment with metoclopramide and cimetidine for presumed gastroesophageal reflux was not effective. The patient had normal T-cell CD4 and CD8 subsets and was human immunodeficiency virus (HIV) antibody negative. Upper gastrointestinal endoscopy revealed C. albicans esophagitis which was treated with oral nystatin. The esophagitis had resolved completely when reassessed postpartum. The use of histamine₂ blockers is associated with an increased risk for fungal esophagitis and may have been a contributing cause in this case.

Conclusion: Pregnant patients with persistent nausea, vomiting, and weight loss should be evaluated by endoscopy for fungal esophagitis.

Amphotericin B induced abnormalities in human platelets

Aims-To investigate in vitro the effect of amphotericin B on platelets in order to understand poor platelet recovery in patients receiving platelet transfusions and amphotericin B simultaneously.Methods-Washed platelets were isolated from platelet concentrates and exposed to amphotericin B (4 mug/ml) for one hour. Platelet function was assessed by aggregation response to thrombin (0-0.6 U/ml), serotonin release, response to hypotonic stress, and mean platelet volume. The expression of surface membrane glycoprotein (GP) Ib-IX complex, GPIIb-IIIa complex and CD62P (P-selectin) was examined by flow cytometry using fluorescence labelled monoclonal antibodies. Heterotypic cell adhesion was measured in amphotericin B treated platelets coincubated with isolated, autologous polymorphonuclear leucocytes (PMN) by flow cytometric analysis.Results-Amphotericin B induced platelet dysfunction. The rate of aggregation by thrombin, serotonin uptake and thrombin induced release of serotonin, and the response of platelets to hypotonic stress were inhibited. There was up to a two-fold increase in the mean platelet volume. The expression of platelet surface GPIb-IX and GPIIb-IIIa was not affected. P-selectin, normally expressed only on the surface of activated platelets, was also expressed on unactivated platelets. Amphotericin B increased platelet adherence to PMN and the number of platelets bound per PMN.Conclusions-In vitro, amphotericin B induces P-selectin expression on the surface of unactivated platelets and increases platelet adhesion to PMN, which is exacerbated by storage. Platelet dysfunction resulting from exposure to amphotericin B may contribute to poor platelet recovery in vivo when amphotericin B is administered concomitantly with platelet transfusion.

Role of amphotericin B upon enhancement of protective immunity elicited by oral administration with liposome-encapsulated-Japanese encephalitis virus nonstructural protein 1 (NS1) in mice

Amphotericin B (AmB) is an antifungal antibiotic the activity of which has been associated with modulation of pro-inflammatory cytokines expression in cultured cells. Herein we reveal that co-administration with AmB enhances the immunogenicity of oral Lip-JENS1 vaccine which derived from liposomes functionalized with DSPC (distearoylphosphatidylcholine) and cholesterol (2:1, molar ratio)-bearing JE virus NS1 protein (600 microg ml(-1)). Oral single dose of Lip-JENS1 elicited a detectable serum NS1-specific IgG antibody response from a mouse model. Remarkably, the addition of AmB (125 microg per mouse), particularly, 2 h prior to, but not simultaneously with, the administration of Lip-JENS1 significantly enhanced the systemic antigen-specific antibody response, providing superior protection against lethal JEV challenges. Further, we observed AmB-induced the transcription of cytokine expression and translocation of transcriptional factor NF-kappaB from the cytoplasm to the nucleus for the murine macrophage J774A.1. Moreover, Peyer's-patch lymphocytes (PPL) from AmB-treated mice produced high levels of IL-1beta, IL-6 and TNF-alpha expression compared to the corresponding control of cells from non-treated mice. Taken together, the results suggest that AmB exerts a profound influence upon mucosal vaccination with Lip-JENS1, possibly playing an adjuvant-augmented role to "fine-tune" humoral as well as cellular immune response, thus conferring enhanced protective immunity for immunising individuals against JE infection.

Black yeast symbionts compromise the efficiency of antibiotic defenses in fungus-growing ants

Multiplayer symbioses are common in nature, but our understanding of the ecological dynamics occurring in complex symbioses is limited. The tripartite mutualism between fungus-growing ants, their fungal cultivars, and antibiotic-producing bacteria exemplifies symbiotic complexity. Here we reveal how black yeasts, newly described symbionts of the ant-microbe system, compromise the efficiency of bacteria-derived antibiotic defense in fungus-growing ants. We found that symbiotic black yeasts acquire nutrients from the ants' bacterial mutualist, and suppress bacterial growth. Experimental manipulation of ant colonies and their symbionts shows that ants infected with black yeasts are significantly less effective at defending their fungus garden from Escovopsis, a prevalent and specialized pathogen. The reduction of mutualistic bacterial biomass on ants, likely caused by black yeast symbionts, apparently reduces the quantity of antibiotics available to inhibit the garden pathogen. Success of the ant-fungal mutualism is directly dependent on fungus garden health. Thus our finding that black yeasts compromise the ants' ability to deal with the garden parasite indicates that it is an integral component of the symbiosis. This is further evidence that a full understanding of symbiotic associations requires examining the direct and indirect interactions of symbionts in their ecological community context.

Chemical combination effects predict connectivity in biological systems

Chemical synergies can be novel probes of biological systems.

Simulated response shapes depend on target connectivity in a pathway.

Experiments with yeast and cancer cells confirm simulated effects.

Profiles across many combinations yield target location information.

Living organisms are built of interacting components, whose function and dysfunction can be described through dynamic network models (Davidson et al, 2002). Systems Biology involves the iterative construction of such models (Ideker et al, 2001), and may eventually improve the understanding of diseases using in silico simulations. Such simulations may eventually permit drugs to be prioritized for clinical trials, reducing potential risks and increasing the likelihood of successful outcomes. Given the complexity of biological systems, constructing realistic models will require large and diverse sets of connectivity data.

Chemical combinations provide a new window into biological connectivity. Information gleaned from targeted combinations, such as paired mutations (Tong et al, 2004), has proven to be especially useful for revealing functional interactions between components. We have been screening chemical combinations for therapeutic synergies (Borisy et al, 2003; Zimmermann et al, 2007), collecting full-dose matrices where combinations are tested in all possible pairings of serially diluted single agent doses (Figure 1). Such screens yield a variety of response surfaces with distinct shapes for combinations that work through different known mechanisms, suggesting that combination effects may contain information on the nature of functional connections between drug targets.

Simulations of biological pathways predict synergistic responses to inhibitors that depend on target connectivity. We explored theoretical predictions by simulating a metabolic pathway with pairs of inhibitors aimed at different targets with varying doses. We found that the shape of each combination response depended on how the inhibitor pair's targets were connected in the pathway (Figure 2). The predicted response shapes were robust to plausible variations in the simulated pathway that did not affect the network topology (e.g., kinetic assumptions, parameter values, and nonlinear response functions), but were very sensitive to topological alterations in the modelled network (e.g., feedback regulation or changing the type of junction at a branch point). These findings suggest that connectivity of the inhibitor targets has a major influence on combination response morphology.

The predicted shapes were experimentally confirmed in yeast combination experiments. The proliferation experiment used drugs focused on the sterol biosynthesis pathway, which is mostly linear between the targets covered in this study, and is known to be regulated by negative feedback (Gardner et al, 2001). The combinations between sterol inhibitors confirmed expectations from our simulations, showing dose-additive responses for pairs targeting the same enzyme and strong synergies across enzymes of the shape predicted in our simulations for linear pathways under negative feedback. Combinations across pathways showed much more variable responses with a trend towards less synergy on average.

Further experimental support was obtained from human cells. A combination screen of 90 annotated drugs in a human tumour cell line (HCT116) proliferation assay produced strong synergies for combinations within pathways and more variable effects between targeted functions. Synergy profiles (sets of all synergy scores involving each drug) also showed a greater degree of similarity for pairs of drugs with related targets. Finally, the most extreme outliers were dominated by inhibitors of kinases that are especially critical for HCT116 proliferation (Awwad et al, 2003), with effects that are consistent across mechanistic replicates, showing that chemical combinations can highlight biologically relevant cellular processes.

This study demonstrates the potential of chemical combinations for exploring functional connectivity in biological systems. This information complements genetic studies by providing more details through variable dosing, by directly targeting single domains of multi-domain proteins, and by probing cell types that are not amenable to mutagenesis. Responses from large chemical combination screens can be used to identify molecular targets through chemical–genetic profiling (Macdonald et al, 2006), or to directly constrain network models by means of a prediction-validation procedure (Ideker et al, 2001). This initial exploration can be extended to cover a wider range of response shapes and network topologies, as well as to combinations of three or more chemical agents. Moreover, this approach may even be applicable to non-biological systems where responses to targeted perturbations can be measured.

Efforts to construct therapeutically useful models of biological systems require large and diverse sets of data on functional connections between their components. Here we show that cellular responses to combinations of chemicals reveal how their biological targets are connected. Simulations of pathways with pairs of inhibitors at varying doses predict distinct response surface shapes that are reproduced in a yeast experiment, with further support from a larger screen using human tumour cells. The response morphology yields detailed connectivity constraints between nearby targets, and synergy profiles across many combinations show relatedness between targets in the whole network. Constraints from chemical combinations complement genetic studies, because they probe different cellular components and can be applied to disease models that are not amenable to mutagenesis. Chemical probes also offer increased flexibility, as they can be continuously dosed, temporally controlled, and readily combined. After extending this initial study to cover a wider range of combination effects and pathway topologies, chemical combinations may be used to refine network models or to identify novel targets. This response surface methodology may even apply to non-biological systems where responses to targeted perturbations can be measured.

Efficacies of caspofungin and a combination of caspofungin and meropenem in the treatment of murine disseminated candidiasis

Disseminated candidiasis is relatively common in immunocompromised patients. The treatment protocol of these patients usually includes broad-spectrum antibiotics and also emprical antifungals initiated due to unresponsiveness to antibiotics. In this study the efficacies of caspofungin and meropenem - separately and together - in mice with disseminated candidiasis were studied. Immunocompetent mice were infected intravenously with 2x10(6) CFU of Candida albicans. At 24 h postinfection, intraperitoneal therapy was initiated and was continued for 7 days. Therapy groups included those given caspofungin (0.5, 1.25, 5 mg/kg/day), meropenem (20 mg/kg/day), and a combination of the two drugs. The outcome of therapy was evaluated by kidney tissue burden studies and histologic examination. In vitro, drug susceptibilities were tested by checkerboard analysis. Kidney CFU counts showed that mice that had received both drugs had lower residual burdens. Caspofungin was effective at doses of 0.5, 1.25, 5 mg/kg compared to infected untreated controls. In vitro, MICs of caspofungin and meropenem were <0.075 micro g/ml and >64 micro g/ml, respectively. Synergism was observed with the combination. Histopathology showed that the degree of inflammation was 25% less and tubular necrosis was more restricted in combined therapy than monotherapy. The results indicate that concurrent caspofungin and meropenem therapy may be beneficial.

An Overview of Antifungal Drugs and Their Use for Treatment of Deep and Superficial Mycoses in Animals

Fungal infections are often challenging to manage, given the limited numbers of therapeutics and a general lack of applicable clinical literature for their use in a given animal species. This article reviews some of the underlying principles that can affect the therapeutic outcome for a given antifungal, and provides specific information from the literature that is intended to highlight the distinctive properties of the most commonly used antifungals in veterinary medicine to better facilitate their successful application in clinical practice.

New agents for the treatment of systemic fungal infections – current status

Systemic antifungal chemotherapy is enjoying its most dynamic era. More antifungal agents are under development than ever before, including agents in entirely new classes. Major goals of current investigations are to identify compounds with a wide spectrum of activity, minimal toxicity and a high degree of target specificity. The antifungal drugs in development include new azoles {voriconazole, posaconazole (formerly SCH-56592), ravuconazole (formerly BMS-207147)}, lipid formulations of amphotericin B, a lipid formulation of nystatin, echinocandins {anidulafungin (formerly, LY-303366, VER-002), caspofungin (formerly MK-991), micafungin (formerly FK-463)}, antifungal peptides other than echinocandins, and sordarin derivatives. This discussion reviews the currently available antifungal agents and summarises the developmental issues that surround these new systemic antifungal drugs.

Influence of amphotericin B deoxycholate or amphotericin B colloidal dispersion on renal tubule epithelium in rat

Amphotericin B deoxycholate (AmB) or Amphotericin B colloidal dispersion (ABCD) are used in clinics for the treatment of systemic fungal infections. The goal of our study was to compare the nephrotoxicity of these drugs in rat kidney. The effects of AmB and ABCD on the ultrastructure of the epithelium of renal tubules were studied and evaluated using morphometric and statistical methods. Two groups of 3 animals were established: group 1 was treated with AmB desoxycholate and group 2, to which ABCD was applied. AmB caused more than ABCD ultrastructural changes in the cytoplasm of the epithelial cells: damage to mitochondria, vacuolation of cytoplasm, and increased values of volume density of peroxisomes. However, we failed to observe significant differences in morphology and density of the other cell organelles. The proximal tubules seemed to be more sensitive to the nephrotoxic influence of both formulas than the distal tubules of rat kidney. Although, AmB causes more severe damage than ABCD, both drugs cause damage to renal tubuli.

The life and death of sponge cells

Cell viability is an essential touchstone in the study of the effect of medium components on cell physiology. We developed a flow-cytometric assay to determine sponge-cell viability, based on the combined use of fluorescein diacetate (FDA) and propidium iodide (PI). Cell fluorescence measurements based on incubation of cells with FDA or PI resulted in a useful and reproducible estimate of the viability of primary sponge-cell cultures. We studied the effects of temperature, ammonium, and the fungicide amphotericin B on the viability of a primary-cell culture from the marine sponge Suberites domuncula using the aforementioned flow-cytometric assay. S. domuncula cells die rapidly at a temperature of >or=22 degrees C, but they are insensitive to ammonium concentrations of up to 25 mM. Amphotericin B, which is frequently used in sponge-cell culture media, was found to be toxic to S. domuncula cells.

Update on antifungal therapy

Fungal pathogens are becoming increasingly important for human and small animal medicine. This article highlights many standards-of-care and new agents for treatment of these pathogens for small animals and people.

A double-blind, randomized, controlled trial of amphotericin B colloidal dispersion versus amphotericin B for treatment of invasive aspergillosis in immunocompromised patients

We report a randomized, double-blind, multicenter trial in which amphotericin B colloidal dispersion (ABCD [Amphotec]; 6 mg/kg/day) was compared with amphotericin B (AmB; 1.0-1.5 mg/kg/day) for the treatment of invasive aspergillosis in 174 patients. For evaluable patients in the ABCD and AmB treatment groups, respective rates of therapeutic response (52% vs. 51%; P=1.0), mortality (36% vs. 45%; P=.4), and death due to fungal infection (32% vs. 26%; P=.7) were similar. Renal toxicity was lower (25% vs. 49%; P=.002) and the median time to onset of nephrotoxicity was longer (301 vs. 22 days; P<.001) in patients treated with ABCD. Rates of drug-related toxicity in patients receiving ABCD and AmB, respectively, were 53% versus 30% (chills), 27% versus 16% (fever), 1% versus 4% (hypoxia) and 22% versus 24% (toxicity requiring study drug discontinuation). ABCD appears to have equivalent efficacy and superior renal safety, compared with AmB, in the treatment of invasive aspergillosis. However, infusion-related chills and fever occurred more frequently in patients receiving ABCD than in those receiving AmB.

Application of capillary zone electrophoresis with off-line solid-phase extraction to in vitro metabolism studies of antifungals

A simple and robust solid-phase extraction (SPE) procedure for the cleanup and sample preconcentration of antifungals (ketoconazole, clotrimazole, itraconazole, fluconazole, and voriconazole) and their metabolites after incubation with human liver microsomes, as well as a simplified capillary zone electrophoresis (CZE) method for their rapid analysis, have been developed to determine the stability of these compounds in in vitro samples. Three different sample pretreatment procedures using SPE with reversed-phase sorbents (100 mg C8, 100 mg C18, and 30 mg Oasis-HLB) were studied. The highest and most reproducible recoveries were obtained using a 30 mg Oasis-HLB sorbent and methanol containing 2% acetic acid as eluent. Enrichment by a factor of about four times was achieved by reconstituting the final SPE eluates to a small volume. For the CZE separation, good separations without interfering peaks due to the in vitro matrix were obtained with a simple running electrolyte using a fused-silica capillary. The best separation for all components originated by each tested drug after incubation with human liver microsomes (unmetabolized parent drug and its metabolites) was obtained using a 0.05 M phosphate running buffer (pH 2.2) without additives. The effect of the injection volume was also investigated in order to obtain the best sensitivity. Performance levels in terms of precision, linearity, limits of detection, and robustness were determined.

Optimization of the separation of a group of antifungals by capillary zone electrophoresis

Two simple, rapid, and efficient methods for the analysis of seven antifungal compounds have been developed by capillary zone electrophoresis. Resolutions higher than 1.5 were obtained using 0.025 M phosphate buffer (pH 2.30) (analysis time close to 9 min) or 0.2 M formic acid (pH 2.15) (analysis time close to 6 min), with an applied voltage of 20 kV and a temperature of 30 degrees C. The highest sensitivity and selectivity can be obtained using phosphate buffer but the shortest analysis times are achieved in the formic system. The analytical characteristics of the optimized methods were investigated. The reproducibility obtained for migration times (RSD(n = 10) < or = 1.0%) and peak areas (RSD(n = 10) < or = 4.3%) was acceptable, but better reproducibilities were obtained when verapamil was used as internal standard (RSD(n = 10) < 0.4% for relative migration times and RSD(n = 10) < or = 2.2% for peak area ratios). The lowest limit of detection was obtained for clotrimazole (0.12 microg/ml) and the highest for fluconazole and voriconazole (0.90 microg/ml). The lowest and the highest limits of quantitation were, respectively, 0.40 microg/ml for clotrimazole and 3.00 microg/ml for fluconazole and voriconazole.

Hamycin treatment of candidiasis in normal and diabetic rats

Hamycin, a heptaene antifungal antibiotic was compared with amphotericin B in the treatment of established systemic infection with Candida albicans in normal and diabetic rats. In normal rats, orally administered hamycin at 10 mg kg(-1) per day for 7 days reduced Candida colony counts in the kidneys and livers as well as amphotericin B did and was nearly as effective as amphotericin B in a 21-day treatment trial. There was no further reduction in Candida colony counts when normal rats were treated with hamycin at 25 mg kg(-1) twice a day for 7 days. In streptozotocin induced diabetic rats, hamycin at 20 mg kg(-1) per day for either 7 or 21 days compared favourably with amphotericin B in efficacy. Results of the present study suggest that oral hamycin may be useful in the treatment of established disseminated candidiasis in normal as well as diabetic hosts.

Update on the cutaneous manifestations of HIV infection. Clinical and pathologic features

Skin is the most commonly affected organ in patients with HIV. As such, cutaneous manifestations of HIV infection have been the subject of intense scrutiny as well as the topic of many articles. A broad range of infectious and noninfectious skin lesions may develop during the course of the disease. This article discusses the clinical and pathological cutaneous manifestations of HIV infection.

Update on cutaneous manifestations of HIV infection

The skin is affected in virtually all patients with HIV infection. Many articles and several books have been published that deal with these disorders for a number of reasons. First, cutaneous disease may serve as the initial or only problem that the patient suffers for much of the course of the HIV infection. Second, serious opportunistic infections may present for the first time in the skin, so that a skin lesion may be a harbinger of the patient's having a life-threatening illness. Third, skin disorders in these patients may appear unusual and hence may not be accurately diagnosed by clinical inspection alone. Furthermore, response to treatment may be poorer than expected. Thus, skin diseases in the HIV-infected patient are important and, in some cases, may be the most debilitating element of the patient's condition.

Transfusing platelets 2 h after the completion of amphotericin-B decreases its detrimental effect on transfused platelet recovery and survival

Platelet transfusion support is required during bone marrow aplasia following ablative chemotherapy and bone marrow progenitor cell transplantation (BMT). Amphotericin-B is frequently given to these patients, both therapeutically and prophylactically, and has been described to have a negative impact on the results of platelet transfusions. We conducted a prospective study of the effect of amphotericin-B on transfused platelet recovery and survival in 81 BMT or acute leukaemia patients. One hundred and ninety-five platelet transfusions administered to 81 consecutive patients were analysed. The platelets were transfused 2 h after the completion of amphotericin-B. Using this schedule resulted in no effect of amphotericin-B on platelet recovery or survival, although platelet increments were modestly depressed in patients receiving high- vs. low-dose amphotericin-B. We conclude that the timing of amphotericin-B infusion be evaluated in patients demonstrating poor platelet recovery and survival. Transfusing platelets at least 2 h after the completion of amphotericin-B decreases the detrimental effect of this antifungal agent on transfused platelet recovery and survival.

Plasma concentration of itraconazole in patients receiving chemotherapy for hematological malignancies: the effect of famotidine on the absorption of itraconazole

Fungal infection is a serious complication in immunocompromised patients, especially those with neutropenia. Itraconazole (ITZ) is expected to be an effective prophylactic agent for fungal infection because it has more activity against Aspergillus species than fluconazole and it is less toxic than amphotericin-B. However, ITZ is available only as an oral capsule, the absorption of which is thought to depend on the presence of acid in the stomach. In this study, the effect of famotidine, an H2-blocker, on the absorption of ITZ was investigated. Patients undergoing chemotherapy for hematological malignancies were enrolled. To minimize the effect of famotidine, the time of ITZ intake was different from that of famotidine intake. The plasma concentrations of ITZ with or without taking famotidine were determined just before and 4 h after ITZ intake. Mean trough and peak concentrations of ITZ without famotidine were 332 ng/ml and 476 ng/ml, respectively. When famotidine was co-administered, the concentrations decreased to 204 ng/ml and 315 ng/ml, respectively. Statistical analyses revealed significant differences between trough concentrations in the presence and absence of famotidine (p = 0.008). There was also a clear tendency toward higher peak concentrations in the plasma concentrations with famotidine (p = 0.06). These findings suggest that famotidine decreases the plasma concentration of ITZ in patients undergoing chemotherapy. Close monitoring of the plasma concentration of ITZ and dose adjustment are required for efficient prophylaxis.

Activity of liposomal nystatin against disseminated Aspergillus fumigatus infection in neutropenic mice

The purpose of this study was to examine the activity of liposomal nystatin against a disseminated Aspergillus fumigatus infection in neutropenic mice. Mice were made neutropenic with 5-fluorouracil and were administered the antifungal drug intravenously for 5 consecutive days beginning 24 h following infection. Liposomal nystatin, at doses as low as 2 mg/kg of body weight/day, protected neutropenic mice against Aspergillus-induced death in a statistically significant manner at the 50-day time point compared to either the no-treatment, the saline, or the empty-liposome group. This protection was approximately the same as that for free nystatin, a positive control. Histopathological results showed that liposomal nystatin cleared the lungs, spleen, pancreas, kidney, and liver of Aspergillus and that there was no organ damage at the day 5 time point, which was after only three doses of liposomal nystatin. Based on these results in mice, it is probable that liposomal nystatin will be effective against Aspergillus infection in humans.

Fluconazole for treatment of fungal infections of the urinary tract in children

Two children with fungal urinary tract infections (UTI) were treated with fluconazole. One had bilateral megaureters, an almost non-functioning right kidney, and a moderately functioning left kidney because of severe vesicoureteric reflux. He underwent a ureteric reimplantation procedure but developed a fungal UTI postoperatively. The other child had bilateral refluxing megaureters, one of which appeared to open ectopically into the urethra. He acquired a fungal infection during intensive and prolonged antibiotic therapy for a bacterial UTI and septicaemia in the neonatal period. Both fungal infections were cured successfully. We recommend fluconazole as a safe and effective antifungal agent that may be used as a drug of choice for this difficult problem.

Diagnosis and treatment of infectious diseases in HIV-infected hosts

Treatment of infectious diseases in patients with HIV infection is of primary importance in patient care. Viral, bacterial, parasitic, and fungal pathogens all may affect these patients. It is essential that accurate diagnoses be made and appropriate therapy be administered as early as possible.

Rapid infusion of amphotericin B in dextrose

OBJECTIVE

To review the data examining the use of rapid infusion of amphotericin B in dextrose infusions.

DATA SOURCES

A MEDLINE search of the English-language literature and review of pertinent references' bibliographies was used to identify articles evaluating the effect of amphotericin B infusion rates on the incidence of adverse reactions.

STUDY SELECTION AND DATA EXTRACTION

Controlled and uncontrolled studies involving humans are reviewed; emphasis is placed on recent comparative trials. Pertinent information, as judged by the authors, was selected for discussion.

DATA SYNTHESIS

Amphotericin B, a polyene antifungal agent with significant toxicity, remains the agent of choice for many serious fungal infections. The potential benefits of rapid administration of amphotericin B in reducing the incidence and/or severity of adverse reactions were noted soon after its introduction. Recent studies have examined the tolerability of rapid (0.75-1 h) amphotericin B infusions. Results of studies assessing the tolerability of rapid amphotericin B infusions suggest that tolerance to infusion-related reactions develops during therapy. Comparative trials have obtained variable results. The comparative trials supporting rapid amphotericin B infusion have generally used crossover designs, enrolled small numbers of patients, and excluded patients with significant renal or cardiovascular dysfunction.

CONCLUSIONS

Rapid amphotericin B infusions should be avoided during initiation of therapy when infusion-related reactions tend to be most problematic, and in patients with cardiovascular disease, renal dysfunction, and potassium disorders because of the potential risk for cardiac arrhythmias. The literature currently available is conflicting and insufficient to support the routine use of rapid amphotericin B infusion.

Treatment of ocular fungal infections with oral fluconazole

PURPOSE

We treated five patients who had ocular fungal infections with oral fluconazole to determine its safety and effectiveness.

METHODS

We reviewed the case histories of the five patients. One patient had coccidioidomycosis and four had endogenous Candida endophthalmitis.

RESULTS

The intraocular fungal infection resolved in all patients.

CONCLUSION

Fluconazole appears to be a safe and effective antifungal agent that can be administered orally and may be a useful agent for treating some intraocular fungal infections.

Salivary concentrations of ketoconazole and fluconazole: implications for drug efficacy in oropharyngeal and esophageal candidiasis

OBJECTIVE

To determine whether salivary concentrations of ketoconazole and fluconazole may explain the apparent disparity between in vitro activity and clinical efficacy observed with these drugs.

DESIGN

Healthy subjects received a single oral dose of ketoconazole 400 mg or fluconazole 100 mg in a randomized, crossover fashion. Saliva was collected at 0, 1, 2, 3, 6, 12, and 24 hours. Blood samples were obtained at 2 and 24 hours. Salivary concentrations and plasma concentrations for each drug were determined by HPLC. Minimum inhibitory concentration (MIC) testing was determined in triplicate on 6 clinical isolates of Candida albicans, and times over the median MIC values were calculated.

PARTICIPANTS

Eight subjects completed the study.

RESULTS

The mean (+/- SD) peak salivary concentration for ketoconazole was 0.119 +/- 0.050 microgram/mL at 3 hours; no subject had a detectable ketoconazole salivary concentration at 24 hours. At 2 and 24 hours, mean ketoconazole plasma concentrations were 7.64 +/- 3.87 and 0.11 +/- 0.05 microgram/mL, respectively. The saliva to plasma concentration ratio at 2 hours was 0.01. The mean peak salivary concentration of fluconazole was 2.56 +/- 0.34 microgram/mL at 3 hours. At 24 hours, the mean salivary concentration was 1.44 +/- 0.33 microgram/mL. At 2 and 24 hours, mean fluconazole plasma concentrations were 4.39 +/- 3.33 and 3.72 +/- 2.83 micrograms/mL, respectively. The saliva to plasma concentration ratio at 2 hours was 0.55. Median MIC values were 0.0625 microgram/mL (range 0.0313-0.125) for ketoconazole and 0.25 microgram/mL (range 0.125-0.5) for fluconazole. Calculated times over which ketoconazole and fluconazole exceeded the median MICs in saliva were approximately 13 and greater than 24 hours, respectively.

CONCLUSIONS

After a single oral dose, fluconazole achieved higher salivary concentrations than did ketoconazole. This may explain the increased clinical efficacy of fluconazole in the treatment of oropharyngeal-esophageal candidiasis when compared with ketoconazole.

Worsening of liver function with fluconazole and review of azole antifungal hepatotoxicity

OBJECTIVE

To report a case of fluconazole worsening of liver dysfunction.

CASE SUMMARY

A patient with hepatitis experienced worsening of her liver function when treated with fluconazole for a Candida infection in her urine. Elevations in aspartate aminotransferase, alanine aminotransferase, and total bilirubin concentrations along with increased prothrombin time and activated partial thromboplastin time were noted as early as the second day of therapy. After discontinuation of the fluconazole, the liver parameters returned to their normal baseline level.

DISCUSSION

Hepatotoxicity associated with azole antifungal therapy is reviewed. This patient experienced elevations in liver function enzymes; the literature relating to this topic is evaluated.

CONCLUSIONS

It is probable that fluconazole therapy was involved in the worsening of this patient's liver function. Liver function should be monitored during the course of fluconazole therapy in patients with underlying liver dysfunction. It appears from the published reports that HIV-positive patients may be at risk for hepatotoxicity with fluconazole.

Use of antifungal therapy in hospitalized patients. II. Results after the marketing of fluconazole

OBJECTIVE

To evaluate the prescribing patterns of antifungal agents in the hospital setting after the introduction of fluconazole, a new broad-spectrum bis-triazole antifungal agent. Also compared are the prescribing patterns of antifungal agents prior to (phase I) and following (phase II) fluconazole marketing.

DESIGN

A prospective cohort of hospitalized patients prescribed topical or systemic antifungal agents. Data were collected from December 1990 to April 1991.

SETTING

Fifty-seven hospitals ranging in size from 100 to more than 500 beds. Sixty-three percent are affiliated with medical schools.

PATIENTS

Participating pharmacists consecutively identified 15 patients receiving systemic antifungal therapy and 5 patients receiving topical antifungal therapy.

INTERVENTIONS

Observational data on patient antifungal therapy, risk factors for fungal infections, comorbidities, concurrent medications, and culture data were collected.

MEASURES

Differences in prescribing patterns before and after the marketing of fluconazole were assessed using t-tests and chi-square tests.

RESULTS

Of 818 patients studied, 615 (75.2 percent) received systemic antifungal therapy. Five hundred forty-six patients received a single antifungal agent; 348 (63.7 percent) received fluconazole, 105 (19.2 percent) received ketoconazole, 92 (16.8 percent) received amphotericin B, and 1 (0.2 percent) received flucytosine. Sixty-nine patients received two or more systemic agents either concurrently or consecutively. The use of parenteral amphotericin B, alone or in combination with flucytosine and/or an azole, declined from 56.8 percent in the phase I study to 24.2 percent in the current study. The use of parenteral therapy also declined from 56.8 to 40.2 percent. Ketoconazole was used in more than 90 percent of the oral and esophageal infections in the phase I study, but its use declined to only 33 percent in this study. Fluconazole was used most frequently across all sites of presumed or documented infections, with the exception of fungemia. Of the presumed or proven systemic or blood infections, amphotericin B was used alone or in combination in 48.4 percent of the patients and fluconazole was used exclusively in 39.0 percent of the patients. Fluconazole was used more often than amphotericin B (22 vs. 3 patients, respectively) for prophylaxis of systemic infections. The overall use of antifungal prophylaxis also increased from the phase I (9.5 percent) to phase II (13.7 percent).

CONCLUSIONS

The introduction of fluconazole had a major impact on the prescribing patterns of antifungal therapy. Although amphotericin B remained the preferred agent for treatment of suspected or proven systemic, central nervous system, or blood infections, use of fluconazole for these indications approached nearly 40 percent. Further studies are needed to address the role of fluconazole in the prophylaxis and treatment of systemic mycoses.

Use of antifungal therapy in hospitalized patients. I. Results prior to the marketing of fluconazole

OBJECTIVE

To evaluate the use of antifungal agents in hospitalized patients prior to marketing of fluconazole and to assess characteristics associated with their use.

DESIGN

A cohort of hospitalized patients receiving topical or systemic antifungal therapy was monitored concurrently.

SETTING

Sixty-nine hospitals ranging in size from 100 to more than 500 beds, 70.1 percent affiliated with medical schools.

PATIENTS

Participating clinical pharmacists each identified 15 consecutive patients receiving systemic antifungal therapy and 5 consecutive patients receiving topical antifungal therapy at their institutions. Data collection began October 1989 and ended March 1990.

INTERVENTION

All data collected were observational in nature, and no patient intervention was required.

MEASURES

Characteristics of patients receiving antifungal therapy were compared using t-tests and chi-square tests. Utilization and patterns of use of antifungal therapy were reported.

RESULTS

The most common risk factors necessitating antifungal therapy, in descending order, were: administration of broad-spectrum antibiotics and/or presence of invasive catheters, carcinoma, AIDS, leukemia or lymphoma, diabetes mellitus, solid organ or bone marrow transplantation, and chronic obstructive pulmonary disease. Five hundred seventeen patients received systemic therapy and 464 (89.7 percent) received a single systemic agent. Of these, 242 (52.2 percent) received amphotericin B, 215 (46.3 percent) received ketoconazole, 6 (1.3 percent) received flucytosine, and 1 (0.2 percent) received intravenous miconazole. Fifty-three patients received two systemic agents either concurrently or consecutively. Ketoconazole was most often used for presumed or documented oral, urogenital, or esophageal infections and amphotericin B was the preferred agent for disseminated infections and fungemia (p < 0.001). Almost half of the patients receiving amphotericin B or ketoconazole (48.3 percent) received these drugs as empiric therapy. Documented infections were more likely to be treated with amphotericin B (54.8 percent) than with ketoconazole (27.4 percent) (p < 0.001). The predominant fungal isolates were Candida albicans, Candida spp., and unspecified yeasts. Amphotericin B toxicity led to discontinuation of drug therapy in only 5.1 percent of cases. Two hundred sixty-nine patients (34.2 percent) received topical antifungal therapy only. Nystatin oral suspension was prescribed to 65.3 percent of the patients, clotrimazole troches to 23.0 percent, amphotericin B irrigation to 10.9 percent, and nystatin tablets to 0.8 percent.

CONCLUSIONS

The utilization patterns of antifungal agents in this survey follow established therapeutic guidelines. Prior to the introduction of fluconazole, amphotericin B was the agent of choice for documented systemic fungal infections. Ketoconazole was more often used for prophylaxis of fungal infections and treatment of oral and esophageal infections.

Chemoprophylaxis for pulmonary aspergillosis during intensive chemotherapy

Three children who developed pulmonary aspergillosis while being treated for leukaemia or non-Hodgkin's lymphoma. Each child continued with intensive myelosuppressive chemotherapy regimens during the infection and each was successfully treated with antifungal prophylaxis based on itraconazole by mouth. Amphotericin B was also given during periods of severe neutropenia. No reactivation of the fungal infection was seen.

Oral azole drugs as systemic antifungal therapy

The oral azole drugs--ketoconazole, fluconazole, and itraconazole--represent a major advance in systemic antifungal therapy. Among the three, fluconazole has the most attractive pharmacologic profile, including the capacity to produce high concentrations of active drug in cerebrospinal fluid and urine. Ketoconazole, the first oral azole to be introduced, is less well tolerated than either fluconazole or itraconazole and is associated with more clinically important toxic effects, including hepatitis and inhibition of steroid hormone synthesis. However, ketoconazole is less expensive than fluconazole and itraconazole--an especially important consideration for patients receiving long-term therapy. All three drugs are effective alternatives to amphotericin B and flucytosine as therapy for selected systemic mycoses. Ketoconazole and itraconazole are effective in patients with the chronic, indolent forms of the endemic mycoses, including blastomycosis, coccidioidomycosis, and histoplasmosis; itraconazole is also effective in patients with sporotrichosis. Fluconazole is useful in the common forms of fungal meningitis--namely, coccidioidal and cryptococcal meningitis. In addition, fluconazole is effective for selected patients with serious candida syndromes such as candidemia, and itraconazole is the most effective of the azoles for the treatment of aspergillosis.