Newer Systemic Antifungal Agents

Severe Photosensitivity Causing Multifocal Squamous Cell Carcinomas Secondary to Prolonged Voriconazole Therapy

A 32-year-old woman was treated with long-term voriconazole therapy for recurrent aspergillosis associated with chronic granulomatous disease. A short time after commencement of voriconazole therapy, a severe photosensitivity reaction developed. Continued voriconazole exposure led to the development of multifocal facial squamous cell carcinomas. The photosensitivity reaction resolved after the patient changed therapy to posaconazole.

Simultaneous quantification of voriconazole and posaconazole in human plasma by high-performance liquid chromatography with ultra-violet detection

A sensitive and selective high-performance liquid chromatographic (HPLC) method with ultra-violet detection has been developed and validated for the simultaneous determination of posaconazole and voriconazole, two systemic anti-fungal agents. An internal standard diazepam was added to 100 microL of human plasma followed by 3 mL of hexane-methylene chloride (70:30, v/v). The organic layer was evaporated to dryness and the residue was reconstituted with 100 microL of mobile phase before being injected in the chromatographic system. The compounds were separated on a C8 column using sodium potassium phosphate buffer (0.04 M, pH 6.0): acetonitrile:ultrapure water (45:52.5:2.5, v/v/v) as mobile phase. All compounds were detected at a wavelength of 255 nm. The assay was linear and validated over the range 0.2-10.0 mg/L for voriconazole and 0.05-10.0 mg/L for posaconazole. The biases were comprised between -3 and 5% for voriconazole and -2 and 8% for posaconazole. The intra- and inter-day precisions of the method were lower than 8% for the routine quality control (QC). The mean recovery was 98% for voriconazole and 108% for posaconazole. This method provides a useful tool for therapeutic drug monitoring.

Posaconazole: clinical pharmacology and potential for management of fungal infections

Posaconazole is a novel lipophilic antifungal triazole that inhibits cytochrome P450-dependent 14-alpha demethylase in the biosynthetic pathway of ergosterol. Inhibition of this enzyme leads to an accumulation of toxic 14-alpha methylsterols and a depletion of ergosterol, resulting in a perturbation of the function of the fungal cell membrane and blockage of cell growth and division. In vitro, posaconazole has potent and broad-spectrum activity against opportunistic, endemic and dermatophytic fungi. This activity extends to organisms that are often refractory to existing triazoles, amphotericin B or echinocandins, such as Candida glabrata, Candida krusei, Aspergillus terreus, Fusarium spp. and the Zygomycetes. A large variety of animal models of invasive fungal infections have provided consistent evidence of efficacy against these organisms in vivo, both in normal and immunocompromised animals. Posaconazole is available as an oral suspension and optimal exposure is achieved when the drug is administered in two to four divided doses along with food or a nutritional supplement. The compound has a large volume of distribution, in the order of 5 l/kg, and a half-life of approximately 20 h. Posaconazole is not metabolized to a significant extent through the cytochrome P450 enzyme system and is primarily excreted in an unchanged form in the feces. Although it is inhibitory, cytochrome P3A4 has no effect on 1A2, 2C8, 2C9, 2D6 and 2E1 isoenzymes, and therefore, a limited spectrum of drug-drug interactions can be expected. Pharmacokinetic studies in special populations revealed no necessity for dosage adjustment based on differences in age, gender, race, renal or hepatic function. Posaconazole has demonstrated strong antifungal efficacy in Phase II and III clinical trials in immunocompromised patients with oropharyngeal and esophageal candidiasis. Posaconazole also showed promising efficacy as salvage therapy in a large Phase II study including 330 patients with invasive fungal infections intolerant to or refractory to standard therapies. Posaconazole appears to be well tolerated in a manner comparable with that of fluconazole and it is currently under regulatory review in the USA and Europe for the treatment of refractory invasive fungal infections. This drug profile reviews the preclinical and clinical pharmacology of posaconazole and its potential role for prevention and treatment of invasive fungal infections.

Caspofungin for the treatment of fungal infections: a systematic review of randomized controlled trials

During the last decade, owing to the low effectiveness and high toxicity of older antifungals, new antifungal agents have been released to the market for the treatment of patients with fungal infections. Several randomized controlled trials (RCTs) have been designed to evaluate the effectiveness of caspofungin in comparison with other antifungal agents. This review was conducted to examine further the role of caspofungin in the treatment of patients with fungal, mainly Candida, infections. Two reviewers independently performed the literature search, study selection and data extraction from relevant RCTs. A total of six RCTs comparing caspofungin with amphotericin B (deoxycholate in four and liposomal in one RCT) or fluconazole (in one RCT), which studied a total of 1974 patients, were included in our review. Success of the applied treatment in the clinically evaluable patients was achieved in 496/943 (52.6%) of the caspofungin-treated patients and in 381/852 (44.7%) of the amphotericin B- and lipid amphotericin B-treated patients. Discontinuation due to drug toxicity was significantly less common in patients receiving caspofungin than amphotericin B (odds ratio (OR) 0.25, 95% confidence interval (CI) 0.07-0.85, random effects model). Development of nephrotoxicity, hypokalaemia and fever also occurred significantly less often with caspofungin than amphotericin B (OR 0.23, 95% CI 0.14-0.36, fixed effects model; OR 0.3, 95% CI 0.12-0.76, random effects model; and OR 0.26, 95% CI 0.08-0.79, random effects model, respectively). No difference in mortality was noted. Caspofungin was associated with better clinical outcomes (higher cure and fewer adverse effects) than amphotericin B in the treatment of patients with fungal infections.

Treatment of bilateral candidal endophthalmitis with intravenous caspofungin

PURPOSE

Fungal resistances to drugs are increasing. Caspofungin is a new antifungal agent effective in the treatment of invasive candidiasis. We report a case of candidal endophthalmitis that responded adequately to caspofungin.

METHODS

A 24-year-old man with acute myeloid leukemia presented with vision loss in both eyes. Visual acuity was 20/50 in the right eye and counting fingers in the left eye. Fundus examination revealed multiple, premacular, vitreous, pearl stringshaped condensations in the right eye and a subretinal abscess in the left eye. Treatment with 50 mg of intravenous caspofungin once daily was started.

RESULTS

After 1 month, inflammation in both eyes had decreased, although the left eye developed macular scarring. Medication at discharge was intravenous caspofungin once daily for another 6 weeks. Nine months after presentation, the patient had residual vitreous condensations in the premacular region of the right eye with visual acuity of 20/25 and severe macular scarring in the left eye with visual acuity of 20/100.

CONCLUSION

This case adds support for the use of caspofungin as monotherapy for candidal endophthalmitis. Further studies are necessary to determine treatment options for the new antifungal agents.

Invasive esophageal aspergillosis associated with acute myelogenous leukemia: successful therapy with combination caspofungin and liposomal amphotericin B

Aspergillosis is one of the most common invasive fungal infections in patients with leukemia. In this patient group, this form of Aspergillus infection is a life-threatening condition with a mortality of 50-100%. The lungs are most often affected, but the esophagus can also be involved.The authors report the case of a child with leukemia who developed invasive esophageal aspergillosis. The condition was diagnosed by microscopic examination of endoscopic biopsy specimens. The patient was already receiving empirical liposomal amphotericin B when the diagnosis was made, so a second antifungal (caspofungin) was added to the regimen. This combination was successful. This case to demonstrates a case of successful treatment of invasive esophageal aspergillosis using combination therapy of liposomal amphotericin B and caspofungin.

Filamentous fungi in a tertiary care hospital: environmental surveillance and susceptibility to antifungal drugs

OBJECTIVE

To evaluate filamentous fungi with respect to environmental load and potential drug resistance in a tertiary care teaching hospital.

DESIGN

Monthly survey in 2 buildings of the hospital during a 12-month period.

SETTING

Hippokration Hospital in Thessaloniki, Greece.

METHODS

Air, surface, and tap water sampling was performed in 4 departments with high-risk patients. As sampling sites, the solid-organ transplantation department and the hematology department (in the older building) and the pediatric oncology department and the pediatric intensive care unit (in the newer building) were selected.

RESULTS

From January to May of 2000, the fungal load in air (FLA) was low, ranging from 0 to 12 colony-forming units (cfu) per m(3) in both buildings. During the summer months, when high temperature and humidity predominate, the FLA increased to 4-56 cfu/m(3). The fungi commonly recovered from culture of air specimens were Aspergillus niger (25.9%), Aspergillus flavus (17.7%), and Aspergillus fumigatus (12.4%). Non-Aspergillus filamentous fungi, such as Zygomycetes and Dematiaceous species, were also recovered. The pediatric intensive care unit had the lowest mean FLA (7.7 cfu/m(3)), compared with the pediatric oncology department (8.7 cfu/m(3)), the solid-organ transplantation department (16.1 cfu/m(3)), and the hematology department (22.6 cfu/m(3)). Environmental surfaces were swabbed, and 62.7% of the swab samples cultured yielded filamentous fungi similar to the fungi recovered from air but with low numbers of colony-forming units. Despite vigorous sampling, culture of tap water yielded no fungi. The increase in FLA observed during the summer coincided with renovation in the building that housed the solid-organ transplantation and hematology departments. All 54 Aspergillus air isolates randomly selected exhibited relatively low minimum inhibitory or effective concentrations for amphotericin B, itraconazole, voriconazole, posaconazole, micafungin, and anidulafungin.

CONCLUSION

Air and surface fungal loads may vary in different departments of the same hospital, especially during months when the temperature and humidity are high. Environmental Aspergillus isolates are characterized by lack of resistance to clinically important antifungal agents.

Scedosporium Infection in a Tertiary Care Cancer Center: A Review of 25 Cases from 1989-2006

We reviewed the records of patients with cancer who had Scedosporium infection (due to Scedosporium apiospermum and Scedosporium prolificans in 21 and 4 patients, respectively). The incidence of Scedosporium infection increased from 0.82 cases per 100,000 patient-inpatient days (in 1993-1998) to 1.33 cases per 100,000 patient-inpatient days (in 1999-2005). Cases of S. prolificans infection occurred only after 2000. Dissemination occurred in 16 patients (64%). The 12-week mortality rates were 70% and 100% for S. apiospermum and S. prolificans infection, respectively.

Voriconazole: a broad spectrum triazole for the treatment of serious and invasive fungal infections

For many years, serious systemic fungal infections have been treated with amphotericin B or narrow-spectrum azole antifungals. These treatments have been effective in many patients, but are associated with tolerability or pharmacokinetic concerns, or suboptimal antifungal activity in some patient groups. Voriconazole is a second-generation triazole with an extended spectrum of activity offering the potential to treat life-threatening fungal infections. The drug is available for intravenous or oral administration and has been shown to be effective in invasive aspergillosis, fluconazole-susceptible and -resistant candidiasis, and infections caused by various other fungal pathogens, including some formerly refractory organisms. Voriconazole is generally well tolerated with transient visual disturbances, liver enzyme abnormalities and skin rashes being the most common adverse events reported, but these rarely lead to treatment discontinuation.

DETECTION OF ASPERGILLUS SPP. IN BIOLOGICAL SAMPLES BY REAL-TIME PCR

BACKGROUND

Recently, the proportion of invasive infections caused by the filamentous fungi of the Aspergillus genus are growing in immunocompromised persons particularly in transplant recipients and neutropenic patients. Unfortunately, laboratory diagnostics of invasive aspergillosis remains extremely difficult, mainly with regard to the sensitivity of the methods and to the correct interpretation of the results in particular.

AIM

The aim of this work was to design a standard and reproducible Aspergillus DNA detection method and its validation. The second aim was to practically use this method for diagnosis of Aspergillus DNA in various samples in patients.

METHOD

Real-time PCR with two hybridization probes. Amplification and on-line quantification was carried out on a LightCycler 1.5 Instrument.

RESULTS

Specificity of the reaction was tested for A. fumigatus, A. flavus, A. niger and A. terreus, and its sensitivity was determined at 5 copies per ml. The reproducibility of the results was comparable to other methods, reported in the literature. Applicability of the real-time PCR was assessed for detection of Aspergillus DNA in 354 various clinical samples taken from 179 patients at risk of invasive aspergillosis over the period of 33 months. Of 354 samples 103 (29.10 %) taken from 65 patients (36.31 %) were evaluated as positive. Over one year, the percentage of positive samples was mostly about 30 % or less per month.

CONCLUSIONS

Our results demonstrate the high sensitivity, specificity and reproducibility of this technique, and its usefulness for rapid laboratory diagnosis of invasive aspergillosis.

The pharmacological importance of cytochrome CYP3A4 in the palliation of symptoms: review and recommendations for avoiding adverse drug interactions

BACKGROUND

Adverse drug interactions are major causes of morbidity, hospitalizations, and mortality. The greatest risk of drug interactions occurs through in the cytochrome system. CYP3A4, the most prevalent cytochrome, accounts for 30-50% of drugs metabolized through type I enzymes.

MATERIALS AND METHODS

Palliative patients received medications for symptoms and co-morbidities, many of which are substrate, inhibitors, or promoters of CYP3A4 activity and expression. A literature review on CYP3A4 was performed pertinent to palliative medicine.

DISCUSSION

In this state of the art review, we discuss the CYP3A4 genetics, and kinetics and common medications, which are substrates or inhibitor/promoters of CYP3A4.

CONCLUSION

We made some recommendations for drug choices to avoid clinically important drug interaction.

Pharmacokinetic/pharmacodynamic profile of voriconazole

Voriconazole is the first available second-generation triazole with potent activity against a broad spectrum of clinically significant fungal pathogens, including Aspergillus,Candida, Cryptococcus neoformans, and some less common moulds. Voriconazole is rapidly absorbed within 2 hours after oral administration and the oral bioavailability is over 90%, thus allowing switching between oral and intravenous formulations when clinically appropriate. Voriconazole shows nonlinear pharmacokinetics due to its capacity-limited elimination, and its pharmacokinetics are therefore dependent upon the administered dose. With increasing dose, voriconazole shows a superproportional increase in area under the plasma concentration-time curve (AUC). In doses used in children (age < 12 years) voriconazole pharmacokinetics appear to be linear. Steady-state plasma concentrations are reached approximately 5 days after both intravenous and oral administration; however, steady state is reached within 24 hours with voriconazole administered as an intravenous loading dose. The volume of distribution of voriconazole is 2-4.6 L/kg, suggesting extensive distribution into extracellular and intracellular compartments. Voriconazole was measured in tissue samples of brain, liver, kidney, heart, lung as well as cerebrospinal fluid. The plasma protein binding is about 60% and independent of dose or plasma concentrations. Clearance is hepatic via N-oxidation by the hepatic cytochrome P450 (CYP) isoenzymes, CYP2C19, CYP2C9 and CYP3A4. The elimination half-life of voriconazole is approximately 6 hours, and approximately 80% of the total dose is recovered in the urine, almost completely as metabolites. As with other azole drugs, the potential for drug interactions is considerable. Voriconazole shows time-dependent fungistatic activity against Candida species and time-dependent slow fungicidal activity against Aspergillus species. A short post-antifungal effect of voriconazole is evident only for Aspergillus species. The predictive pharmacokinetic/pharmacodynamic parameter for voriconazole treatment efficacy in Candida infections is the free drug AUC from 0 to 24 hour : minimum inhibitory concentration ratio.

Candidaemia in patients with haematological disorders and stem cell transplant

The incidence of non-albicans species of Candida has recently increased, especially in patients with malignant haematological disorders receiving fluconazole prophylaxis. A retrospective study of patients who developed candidaemia at Riyadh Armed Forces Hospital between January 1992 and December 2002 was carried out. Thirty one episodes of candidaemia occurred in 27 patients with a variety of haematological disorders. Twenty-four episodes were caused by non-albicans species of Candida and only 7 episodes were caused by C.albicans. The most frequent underlying haematological disorders were acute myeloid leukaemia (AML) followed by acute lymphoblastic leukaemia (ALL). The main predisposing factors for the development of candidaemia were: broad spectrum antibiotics, central venous catheters, neutropenia, cytotoxic chemotherapy, coexisting bacterial infections, steroid therapy, relapsing or untreated primary disease and fluconazole prophylaxis.

Eight episodes were complicated by chronic disseminated candidiasis. Amphotericin-B and amBisome were used in the treatment of Candida infections. The treatment was successful in 86% of the episodes of C. albicans and 50% of the episodes due to nonalbicans species of Candida. The highest mortality rate was encountered with C.tropicalis infections.

Candidaemia is an important cause of mortality and morbidity in patients with malignant haematological disorders and stem cell transplant. The predominance of non-albicans species of Candida especially C.krusei and C.tropicalis is alarming. The early administration of appropriate antifungal therapy and the removal of infected intravascular catheters improve the outcome considerably.

The role of echinocandins, extended-spectrum azoles, and polyenes to treat opportunistic moulds and candida

Three classes of antifungals--polyenes, extended-spectrum azoles, and echinocandins--are now available for treating systemic fungal infections. Guidance for the appropriate use of this expanded variety of antifungals may come from recent clinical trials. Extended-spectrum azoles have excellent in vitro activity against Aspergillus and have been shown to improve clinical outcomes. For Zygomycetes, along with the lipid formulations of amphotericin, of the new agents, only posaconazole has activity. For Candida, the echinocandins offer a broad spectrum of activity. These new agents offer less toxicity and potentially improved efficacy in these difficult infections.

Systemic fungemia and hepatic localizations of Fusarium solani in a liver transplanted patient: an emerging fungal agent

The incidence of invasive fungal infection is increasing especially in the field of transplantation, affecting as many as 50% of bone marrow transplant (BMT) patients with neutropenia and 5-20% of solid-organ transplant (SOT) recipients. Fusarium species are soil saprophytes and plant pathogens. They may cause superficial mycoses or important opportunistic infections in patients with bone marrow suppression and neutropenia, they have been rarely described in solid organ recipients, and up to now there have been no reports of such infection in isolated liver transplanted patients. We describe a case of disseminated Fusarium solani infection with hepatic localization in a liver transplanted patient that resolved with the administration of amphotericin B. Our observation confirms that Fusarium spp. are emerging pathogens that may most frequently affect not only BMT patients and patients with hematological malignancies, but also SOT patients. They may cause both localized and disseminated infection. In conclusion, Fusarium spp. etiology should be considered in the context of infectious diseases following liver transplantation.

Mucormycosis Resulting in Gastric Perforation in a Patient with Acute Myelogenous Leukemia: Report of a Case

Mucormycosis is an uncommon opportunistic fungal infection that may develop in immunocompromised patients with conditions such as diabetes mellitus, leukemia, lymphoma, or human immunodeficiency virus (HIV), or after transplantation with immunosupperessive therapy. We report a case of gastric perforation caused by a mucormycosis infection in a patient with acute myelogenous leukemia (AML). The patient was treated successfully with gastrectomy and the aggressive use of intravenous amphotericin B. He is still alive 1 year after his operation.

Pharmacogenetics, drug-metabolizing enzymes, and clinical practice

The application of pharmacogenetics holds great promise for individualized therapy. However, it has little clinical reality at present, despite many claims. The main problem is that the evidence base supporting genetic testing before therapy is weak. The pharmacology of the drugs subject to inherited variability in metabolism is often complex. Few have simple or single pathways of elimination. Some have active metabolites or enantiomers with different activities and pathways of elimination. Drug dosing is likely to be influenced only if the aggregate molar activity of all active moieties at the site of action is predictably affected by genotype or phenotype. Variation in drug concentration must be significant enough to provide "signal" over and above normal variation, and there must be a genuine concentration-effect relationship. The therapeutic index of the drug will also influence test utility. After considering all of these factors, the benefits of prospective testing need to be weighed against the costs and against other endpoints of effect. It is not surprising that few drugs satisfy these requirements. Drugs (and enzymes) for which there is a reasonable evidence base supporting genotyping or phenotyping include suxamethonium/mivacurium (butyrylcholinesterase), and azathioprine/6-mercaptopurine (thiopurine methyltransferase). Drugs for which there is a potential case for prospective testing include warfarin (CYP2C9), perhexiline (CYP2D6), and perhaps the proton pump inhibitors (CYP2C19). No other drugs have an evidence base that is sufficient to justify prospective testing at present, although some warrant further evaluation. In this review we summarize the current evidence base for pharmacogenetics in relation to drug-metabolizing enzymes.

Emerging echinocandins for treatment of invasive fungal infections

The echinocandins are a new class of antifungals, developed in response to the need for safe and effective antifungals for the treatment of invasive fungal infections. These agents work by inhibiting 1,3-beta-d-glucan synthase, an enzyme essential for production of cell walls in select fungi. Echinocandins appear to demonstrate favourable activity in vitro against a variety of yeasts (including both Candida albicans and non-albicans Candida) as well as select moulds (including Aspergillus spp.) In general, all echninocandins demonstrate a favourable safety profile and require once-daily parenteral administration. Caspofungin is the first of these agents to be available in the US, and is approved for empirical antifungal therapy in febrile neutropenic patients, candidaemia and select forms of invasive candidiasis, and for management of invasive aspergillosis in patients refractory to or intolerant of other therapies. Micafungin was recently approved by the FDA for treatment of oesophageal candidiasis, and for the prophylaxis of fungal infections in haematopoietic stem cell transplant recipients. Emerging data indicate micafungin may have an important role in the treatment of invasive forms of candidiasis. Anidulafungin is an echinocandin approved in the US for treatment of candidaemia and oesophageal candidiasis. Aminocandin (HMR-3702, IP-960) is an investigational agent, with published experience limited to in vitro studies and animal models of infection.

Topical voriconazole solution for cutaneous aspergillosis in a pediatric patient after bone marrow transplant

Invasive aspergillosis seems to be on the rise, especially in immunocompromised children. Historically, only systemic amphotericin B has been effective against Aspergillus. Development of newer antifungal agents, such as voriconazole and caspofungin, has improved the treatment options available for aspergillosis, although no definitive management strategy has been established. Here we describe the use of topical voriconazole combined with systemic antifungal agents for cutaneous aspergillosis in a pediatric patient after bone marrow transplant.

In vitro activities of posaconazole, fluconazole, itraconazole, voriconazole, and amphotericin B against a large collection of clinically important molds and yeasts

The in vitro activity of the novel triazole antifungal agent posaconazole (Noxafil; SCH 56592) was assessed in 45 laboratories against approximately 19,000 clinically important strains of yeasts and molds. The activity of posaconazole was compared with those of itraconazole, fluconazole, voriconazole, and amphotericin B against subsets of the isolates. Strains were tested utilizing Clinical and Laboratory Standards Institute broth microdilution methods using RPMI 1640 medium (except for amphotericin B, which was frequently tested in antibiotic medium 3). MICs were determined at the recommended endpoints and time intervals. Against all fungi in the database (22,850 MICs), the MIC(50) and MIC(90) values for posaconazole were 0.063 microg/ml and 1 mug/ml, respectively. MIC(90) values against all yeasts (18,351 MICs) and molds (4,499 MICs) were both 1 mug/ml. In comparative studies against subsets of the isolates, posaconazole was more active than, or within 1 dilution of, the comparator drugs itraconazole, fluconazole, voriconazole, and amphotericin B against approximately 7,000 isolates of Candida and Cryptococcus spp. Against all molds (1,702 MICs, including 1,423 MICs for Aspergillus isolates), posaconazole was more active than or equal to the comparator drugs in almost every category. Posaconazole was active against isolates of Candida and Aspergillus spp. that exhibit resistance to fluconazole, voriconazole, and amphotericin B and was much more active than the other triazoles against zygomycetes. Posaconazole exhibited potent antifungal activity against a wide variety of clinically important fungal pathogens and was frequently more active than other azoles and amphotericin B.

Animal models testing monotherapy versus combination antifungal therapy: lessons learned and future directions

PURPOSE OF REVIEW

The continued rise in serious fungal infections and rises in therapy failure dictate that more efficacious therapies be developed. Combination therapy using available drugs is an attractive choice, yet primarily only anecdotal clinical data are available. We review here data from animal models as an indicator of future potential.

RECENT FINDINGS

The primary data are from murine studies and we will briefly review chemotherapeutic combination studies, some showing benefit over monotherapy and some showing no benefit over monotherapy. In addition, we will address the potential of immunotherapy in combination with conventional therapy.

SUMMARY

The data derived from animal model studies of antifungal drug efficacy have proven to be predictive of clinical utility. Studies on combination therapy will prove useful to the clinician in evaluating courses of treatment, especially where clinical-trial data are not available or probable in the future.

Pseudallescheriasis in the 21st century

Since its discovery as an agent of mycetoma nearly a century ago, Pseudallescheria boydii with its asexual (synanamorphic) form, Scedosporium apiospermum, is now recognized as an important emerging opportunistic pathogen causing invasive mycosis in immunocompromised patients. The clinical spectrum of pseudallescheriasis is wide. Invasive disease of the lung, CNS and dissemination are serious manifestations in immunocompromised patients. This organism responds poorly to amphotericin B, and its histopathologic resemblance to aspergillosis often results in a delay in diagnosis. In vitro data, animal models and accumulating clinical experience support the use of voriconazole as a primary treatment for pseudallescheriasis. This paper reviews the microbiology, ecology, epidemiologic trends, clinical manifestations and current treatment options of pseudallescheriasis.

Effect of voriconazole on the pharmacokinetics and pharmacodynamics of zolpidem in healthy subjects

AIMS

To assess the effect of voriconazole on the pharmacokinetics and pharmacodynamics of zolpidem.

METHODS

In a randomized cross-over study with two phases, 10 healthy subjects ingested 10 mg of zolpidem with or without oral voriconazole pretreatment. The concentrations of zolpidem were measured in plasma up to 24 h and pharmacodynamic variables were monitored for 12 h.

RESULTS

Voriconazole increased the peak plasma concentration of zolpidem by 1.23-fold [P < 0.05; 90% confidence interval (CI) 1.05, 1.45] and the area under the plasma zolpidem concentration-time curve by 1.48-fold (P < 0.001; 90% CI 1.29, 1.74). The time to peak plasma zolpidem concentration was unchanged by voriconazole but the half-life was prolonged from 3.2 to 4.1 h (P < 0.01; 95% CI on the difference 0.27, 1.45). The pharmacodynamics of zolpidem were unaffected by voriconazole.

CONCLUSION

Voriconazole caused a moderate increase in exposure to zolpidem in healthy young subjects but no clear pharmacodynamic changes were observed between the groups.

Intravitreal Voriconazole for the Treatment of Endogenous Aspergillus Endophthalmitis

OBJECTIVE

To describe the first use of intravitreal voriconazole in a human eye for the treatment of Aspergillus endophthalmitis.

DESIGN

Interventional case report.

PATIENT

A 22-year-old woman receiving immunosuppressive agents 5 weeks after lung transplantation who presented with blurred vision and redness in the right eye.

INTERVENTIONS

Intravitreal injection of voriconazole (100 microg/0.1 ml) with pars plana vitrectomy, given after isolation of A. terreus in the vitreous sample. Previous treatment modalities, including vitrectomy with repeated intravitreal amphotericin B and systemic voriconazole, failed to prevent deterioration.

MAIN OUTCOME MEASURES

Visual acuity (VA) and ocular inflammation.

RESULTS

Significant improvement was observed in VA (to 6/15) and in ocular inflammatory reaction. The patient recovered with no evidence of systemic fungal infection.

CONCLUSION

Intravitreal voriconazole may be used as an adjunct to systemic treatment in patients with Aspergillus endophthalmitis. Further clinical studies are needed to determine how often this approach can safely treat this condition.

Drug interactions during therapy with three major groups of antimicrobial agents

This review focuses on drug-drug interactions with three major groups of antimicrobial agents: macrolides (including azalides and ketolides), quinolones, which are widely used for the treatment of bacterial infections, and azoles, which are used for antifungal therapy. Macrolides and the ketolide telithromycin are potent inhibitors of CYP3A4 and thus interfere with the pharmacokinetics of many other drugs that are metabolised by this enzyme. In contrast, although closely related, azithromycin is not a cytochrome inhibitor. All quinolones form complexes with di- and trivalent cations and, therefore, the absorption of quinolones can be dramatically reduced when given concomitantly with mineral antacids, zinc or iron preparations. Ciprofloxacin exhibits an inhibitory potential for the cytochrome isoenzyme 1A2, resulting in an inhibition of theophylline metabolism. Other quinolones, such as levofloxacin or moxifloxacin, do not interfere with theophylline metabolism. The systemic azoles, such as ketoconazole, itraconazole, fluconazole and voriconazole, are inhibitors of CYP isoenzymes, such as CYP3A4, CYP2C9 and CYP2C19, to varying degrees. In addition, some are substrates of the MDR-1 gene product, P-glycoprotein. These features are the basis for most of the interactions occurring during azole therapy (e.g., in severely ill patients in the hospital who are treated with multiple drugs).

Modern antifungal therapy for neutropenic fever

Empirical antifungal therapy has been shown to decrease the number of documented fungal infections in the setting of persistent fever during neutropenia. For decades, amphotericin B deoxycholate has been considered the agent of choice for first-line therapy in this setting. New antifungal agents associated with less toxicity, including the lipid formulations of amphotericin, voriconazole, and caspofungin, are now available and are considered to be suitable alternative first-line agents. In order to ensure appropriate therapy, however, the clinician must consider not only the differences between these antifungals but also patient-specific factors before initiating treatment.

New and emerging infectious diseases

New and emerging diseases present a constant challenge. Globalization of business, international adoption, immigration, and tourism have contributed to the rapid spread of diseases, such as severe acute respiratory syndrome (SARS). Infectious diseases that emerge in Africa or Asia may arrive on US shores within days. This article reviews the new and emerging pathogens important to dermatologists.

Effects of lipid formulations of amphotericin B on activity of human monocytes against Aspergillus fumigatus

The immunomodulatory effects of liposomal amphotericin B (LAMB), amphotericin B lipid complex, and amphotericin B colloidal dispersion (ABCD) on antifungal activity of human monocytes (MNCs), an important component of antifungal host defense, against Aspergillus fumigatus were compared to those of deoxycholate amphotericin B (DAMB). MNCs from healthy volunteers were incubated with 1 or 5 microg/ml DAMB and 5 or 25 microg/ml lipid formulations for 22 h. Drug-pretreated or untreated MNCs were then washed and assayed for the following: (i) activity against A. fumigatus hyphae by XTT assay at MNC:hypha ratios of 10:1 and 20:1; (ii) production of superoxide anion (O2-) from MNCs in response to hyphae by cytochrome c reduction; (iii) production of hydrogen peroxide (H2O2) and H2O2-dependent intracellular intermediates (DIIs), such as OH- and HOCl, from MNCs in response to A. fumigatus culture supernatant by flow cytometric measurement of dihydrorhodamine-1,2,3 oxidation. With the exception of 1 microg/ml DAMB and 5 mug/ml LAMB or ABCD at 10:1, all amphotericin B formulations at both concentrations and MNC:hypha ratios enhanced MNC-induced damage of A. fumigatus hyphae compared to results with untreated cells (P < 0.01). While MNC O2- production upon hyphal challenge, an early event in oxidative burst, was not affected by the drugs, production of H2O2 and DIIs, late events, were significantly increased by all four drugs (P < 0.01). At clinically relevant concentrations, both conventional amphotericin B and its lipid formulations enhance antihyphal activity of MNCs against A. fumigatus in association with significant augmentation of H2O2 and DIIs but not O2-, further demonstrating the immunomodulatory antifungal activities of these agents.

Zygomycosis: the re-emerging fungal infection

Invasive fungal infections are major medical complications in immunocompromised patients. The recent rise in the incidence of cancer and the increased use of newer medical treatment modalities, including organ transplantations, have resulted in growing numbers of highly immunosuppressed individuals. Although aspergillosis and candidiasis are among the most common invasive mycoses in such patients, there is evidence that the incidence of infectious diseases caused by Zygomycetes has risen significantly over the past decade. Patients with diabetes, malignancies, solid organ or bone marrow transplants, or iron overload and those receiving immunosuppressive agents, deferoxamine therapy, or broad-spectrum antimicrobial drugs are at highest risk for zygomycosis. This review details the emergence and importance of zygomycosis in current clinical practice and its manifestations and management. The etiologic species, pathogenesis and risk factors for zygomycosis are reviewed and updated. The clinical spectrum of zygomycosis is now broader, and it can be difficult to distinguish between mucormycosis and enthomophthoramycosis, both of which can manifest as disease ranging from a superficial infection to an angioinvasive infection with high mortality. Finally, the three-part treatment strategy (antifungal drugs, surgery, control of underlying diseases) is reviewed. Lipid formulations of amphotericin B are the antifungal agents of choice for treatment of zygomycosis. A novel antifungal triazole, posaconazole, has been developed and may become approved for treatment of zygomycosis. The clinical experience with adjunctive treatments like colony-stimulating factors, interferon-gamma, and hyperbaric oxygen therapy is still limited.

The long hard road to a completed Candida albicans genome

After almost a decade of work, the sequencing, assembly, and annotation of the genome of the fungal pathogen Candida albicans is finally close at hand. This review covers the early history of the C. albicans genome project, from the release of early assemblies that provided the impetus for an explosion in functional genomics research, to a community-based annotation and a preview of the work that was necessary for the production of a final genome assembly.

Treatment with caspofungin in immunocompromised paediatric patients: a multicentre survey

OBJECTIVES

Although a paediatric dosage has not been established, caspofungin is occasionally used in paediatric patients. We conducted a multicentre retrospective survey to obtain data on immunocompromised paediatric patients considered to require caspofungin therapy.

METHODS

The survey identified 64 patients (median age: 11.5 years; 25 females, 39 males) with haematological malignancies (48), marrow failure (9), solid tumours (3), haematological disorders (2) and congenital immunodeficiency (2) who received caspofungin for proven (17), probable (14) and possible (17) invasive fungal infections or empirically (16). Caspofungin was administered until intolerance or maximum efficacy at dosages individually determined by the responsible physician for refractory infection (38), intolerance of other agents (10) or as best therapeutic option (16).

RESULTS

The 64 patients received caspofungin for a median of 37 days (range 3-218) as single agent (20) or in combination (44). The median daily maintenance dosage was 1.07 mg/kg (95% CI 1.09-1.35; range 0.40-2.92) or 34.3 mg/m2 (95% CI 32.3-37.3; range 16.3-57.5). In none of the patients was therapy discontinued due to adverse events (AEs). Clinical AEs were mild to moderate and observed in 34 patients (53.1%). While mean glutamate pyruvate transaminase and glutamate oxalate transaminase values were slightly (P < 0.005) higher at the end of treatment (EOT), serum bilirubin, alkaline phosphatase and creatinine values were not different from baseline. Complete responses, partial responses or stabilization were observed in 5/7/3 of 17 patients with proven, in 3/4/3 of 14 patients with probable and in 7/6/1 of 15 evaluable patients with possible invasive infections. Thirteen of 16 patients on empirical therapy completed without breakthrough infection. Overall survival was 75% at the EOT and 70% at 3 months post-EOT, respectively.

CONCLUSIONS

Caspofungin displayed favourable safety and tolerance and may have useful antifungal efficacy in severely immunocompromised paediatric patients.

Caspofungin: a review of its use in the treatment of fungal infections

Caspofungin (Cancidas) is the first of a new class of antifungal agents, the echinocandins, that inhibit the synthesis of the fungal cell wall component beta-(1,3)-D-glucan. Caspofungin is administered once daily by slow intravenous infusion and is used to treat infections caused by Candida spp. and Aspergillus spp. Caspofungin is a valuable new antifungal agent with a novel mechanism of action. In comparative clinical trials, caspofungin was no less effective than liposomal amphotericin B in the empirical treatment of neutropenic patients with persistent fever, amphotericin B deoxycholate in the treatment of invasive candidiasis or fluconazole in the treatment of oesophageal candidiasis. Caspofungin also displayed broadly similar efficacy to amphotericin B deoxycholate in oesophageal or oropharyngeal candidiasis and was effective as salvage therapy in patients with invasive aspergillosis who were refractory to or intolerant of standard therapy. The tolerability profile of caspofungin was similar to that of fluconazole and superior to that of amphotericin B deoxycholate and liposomal amphotericin B. Therefore, in the appropriate indications, caspofungin is a viable alternative to amphotericin B deoxycholate, liposomal amphotericin B or fluconazole.

Population Pharmacokinetic Analysis of Micafungin in Japanese Patients with Fungal Infections

The object of this analysis was to develop a population pharmacokinetic model of micafungin, a new anti-fungal agent of the echinocandin class, to optimize dosing in Japanese patients with fungal infections. Population pharmacokinetics parameters were determined using NONMEM based on pharmacokinetic data from 198 subjects in seven clinical studies, comprising four phase I, two phase II and one pediatric phase III study. The healthy subjects received intravenous infusion of 2.5-150 mg micafungin. Adult and pediatric patients, age range of 8 month to 15 yeras old, were received 25-150 mg and 1-6 mg/kg daily, respectively. A total of 1825 micafungin plasma samples were available for this analysis. Two-compartment pharmacokinetic model was adopted. The clearance of micafungin was influenced by body weight in children and platelet counts (PLT). However the PLT accounted for less than 20% of the variation of micafungin clearance in Japanese subjects. In conclusions, body weight is the primary covariate factor in pediatric patients. The dose adjustment by body weight would be required only pediatric patients for the micafungin therapy in Japanese patients with fungal infection.

Posaconazole: a broad-spectrum triazole antifungal

Posaconazale is a new triazole drug being investigated in phase III clinical trials for the treatment and prevention of invasive fungal infections. In-vitro and in-vivo studies showed that posaconazole has broad-spectrum activity against most Candida species, Cryptococcus neoformans, Aspergillus species, Fusarium species, zygomycetes, and endemic fungi. Posaconazole is given orally two to four times daily. This triazole is widely distributed in the body, metabolised mainly by the liver, and is well tolerated, even in long-term courses. Adverse events are generally mild and include headache and gastrointestinal complaints. Posaconazole has shown promising clinical efficacy against life-threatening fungal infections that are often refractory to the currently available antifungal therapies-eg, invasive aspergillosis, fusariosis, and the emerging zygomycosis.

Therapy of Systemic Fungal Infections: A Pharmacologic Perspective

An increase in the incidence of severe, invasive, systemic fungal infections has been noted over the last decade in human and veterinary medicine. Reports of drug resistance and therapeutic failure to currently available antifungal agents have also been on the rise. Many factors are likely to be involved in these trends, including immune suppression and the use of broad-spectrum antibiotics. The use of fungistatic drugs, suboptimal doses, compounded drugs, poorly absorbed drug formulations, and inadequate tissue penetrations of antifungals also contribute to the development of acquired resistance. Because of the unique chemical complexities of the antifungal agents, drug/drug and drug/food interactions may also play a significant role in poor therapeutic outcome. This review summarizes the pharmacology and toxicology of the antifungal agents in current use for systemic mycosis and introduces some of the newer antifungal agents that anecdotally show very promising results.

Coccidioidomycosis in Persons Infected with HIV Type 1

Coccidioidomycosis is a recognized opportunistic infection among persons infected with human immunodeficiency virus (HIV). Early in the HIV epidemic, most cases presented as overwhelming diffuse pulmonary disease with a high mortality rate. Although these cases are still seen, patients without significant immunodeficiency frequently present with a community-acquired pneumonia syndrome. Diagnosis can be established by cytological staining, culture, or serologic testing. All patients with HIV infection and symptomatic coccidioidomycosis should be treated with antifungal therapy. Severe cases frequently require a combination of therapy with amphotericin B and a triazole antifungal. Therapy for at least 1 year is recommended, but for patients with a focal pulmonary infection and peripheral blood CD4 lymphocyte counts of >250 cells/microL, it may be reasonable to stop therapy after this time. Other manifestations of coccidioidomycosis require prolonged therapy, and life-long treatment is recommended for persons with meningitis.

A human-curated annotation of the Candida albicans genome

Recent sequencing and assembly of the genome for the fungal pathogen Candida albicans used simple automated procedures for the identification of putative genes. We have reviewed the entire assembly, both by hand and with additional bioinformatic resources, to accurately map and describe 6,354 genes and to identify 246 genes whose original database entries contained sequencing errors (or possibly mutations) that affect their reading frame. Comparison with other fungal genomes permitted the identification of numerous fungus-specific genes that might be targeted for antifungal therapy. We also observed that, compared to other fungi, the protein-coding sequences in the C. albicans genome are especially rich in short sequence repeats. Finally, our improved annotation permitted a detailed analysis of several multigene families, and comparative genomic studies showed that C. albicans has a far greater catabolic range, encoding respiratory Complex 1, several novel oxidoreductases and ketone body degrading enzymes, malonyl-CoA and enoyl-CoA carriers, several novel amino acid degrading enzymes, a variety of secreted catabolic lipases and proteases, and numerous transporters to assimilate the resulting nutrients. The results of these efforts will ensure that the Candida research community has uniform and comprehensive genomic information for medical research as well as for future diagnostic and therapeutic applications.

Is It Time to Abandon the Use of Amphotericin B Bladder Irrigation?

In this article, we review the issues surrounding funguria and its management. With this background, the value of bladder irrigation with amphotericin B for the management of funguria is directly examined. Amphotericin B bladder irrigation is used frequently in clinical practice. Although its use is not standardized, there are multiple studies that attempt to show the impact on funguria management. These bladder irrigations have been used either for treatment of funguria or (less commonly) as a diagnostic test in attempts to identify upper urinary tract disease. Despite their widespread therapeutic use and relative safety, it is not clear from our experience and a review of the literature that amphotericin B bladder irrigations have any diagnostic or therapeutic value. The patient may be best served by removal of the urinary catheter, if possible, rather than by instillation of bladder irrigation with amphotericin B.

Antifungal activity of flocculosin, a novel glycolipid isolated from Pseudozyma flocculosa

Flocculosin, a glycolipid isolated from the yeast-like fungus Pseudozyma flocculosa, was investigated for in vitro antifungal activity. The compound displayed antifungal properties against several pathogenic yeasts. Synergistic activity was observed between flocculosin and amphotericin B, and no significant cytotoxicity was demonstrated when tested against human cell lines.

Voriconazole for Invasive Bone Aspergillosis: A Worldwide Experience of 20 Cases

BACKGROUND; Bone aspergillosis remains a rare but potentially devastating fungal disease. Although voriconazole is effective for invasive pulmonary aspergillosis, evidence of its efficacy for aspergillosis located in bone is limited.

METHODS

We report our experience with voriconazole in 4 cases of invasive bone aspergillosis. In addition, all cases of probable and definite bone aspergillosis from the Pfizer clinical database were reviewed and analyzed to determine the safety and efficacy of voriconazole treatment. Global response was evaluated at the end of therapy on the basis of a composite assessment of overall clinical, radiological, and mycological responses.

RESULTS

Twenty patients are described, of whom 18 had definite bone involvement diagnosed (spondylodiskitis in 9, sternum/rib osteomyelitis in 6, and peripheral bone involvement in 5). Of 20 patients, 14 were immunocompromised. Oral or intravenous voriconazole was given as salvage therapy for 18 patients; 2 patients received voriconazole as first-line therapy. Median duration of voriconazole treatment was 83.5 days (range, 4-395 days). Global response at end of therapy was satisfactory in 11 (55%) of 20 patients, including complete responses in 4 patients and partial responses in 7 patients; there were no relapses of infection in the 4 patients with complete response to therapy with voriconazole. Treatment was generally well tolerated.

CONCLUSIONS

Long-term voriconazole treatment is a new therapeutic option for invasive aspergillosis with bone involvement.

Induction of interleukin-1beta, tumour necrosis factor-alpha and apoptosis in mouse organs by amphotericin B is neutralized by conjugation with arabinogalactan

OBJECTIVES

To investigate the possibilities that: (i) organ toxicity of amphotericin B-deoxycholate (AMB-DOC) is related to induction of interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and apoptosis in target organs; and (ii) the reduced toxicity resulting from the conjugation of AMB with water-soluble arabinogalactan (AMB-AG), is related to modulation of these parameters.

METHODS

Organ expression of IL-1beta and TNF-alpha was evaluated by enzyme-linked immunosorbent assay (ELISA) in mouse organ biological fluids and in situ by immunohistochemistry. Tissue damage was evaluated histologically, and apoptosis was demonstrated by terminal dUTP nick end-labelling (TUNEL) staining. AMB-AG conjugate was compared with the micellar (AMB-DOC) and liposomal (AmBisome) AMB formulations.

RESULTS

Treatment with AMB-AG or AmBisome caused no observable histopathological damage in the kidneys. In contrast, treatment with AMB-DOC resulted in disruptive changes and apoptosis in renal tubular cells. These effects were found to correlate with induction of high levels of IL-1beta and TNF-alpha in kidney lysates. Unlike AMB-AG, AMB-DOC also induced enhanced IL-1beta and TNF-alpha expression in lysates of lungs, brain, liver and spleen. The marked elevation of these inflammation-apoptosis-promoting cytokines after treatment with AMB-DOC may mediate its systemic and local renal damage. Treatment with AMB-AG (but not AmBisome) appears to uniquely modulate the in situ expression of IL-1beta and enhance secretion of TNF-alpha in kidneys, effects possibly involved in prevention of apoptosis.

CONCLUSIONS

AMB-related toxicity is associated with induction of IL-1beta, TNF-alpha and apoptosis in organs. These effects were not observed with AMB-AG conjugate, suggesting its potential as a safer formulation for therapy.

Bad bugs need drugs: an update on the development pipeline from the Antimicrobial Availability Task Force of the Infectious Diseases Society of America

The Antimicrobial Availability Task Force (AATF) of the Infectious Diseases Society of America (IDSA) has viewed with concern the decreasing investment by major pharmaceutical companies in antimicrobial research and development. Although smaller companies are stepping forward to address this gap, their success is uncertain. The IDSA proposed legislative and other federal solutions to this emerging public health problem in its July 2004 policy report "Bad Bugs, No Drugs: As Antibiotic R&D Stagnates, a Public Health Crisis Brews." At this time, the legislative response cannot be predicted. To emphasize further the urgency of the problem for the benefit of legislators and policy makers and to capture the ongoing frustration our clinician colleagues experience in their frequent return to an inadequate medicine cabinet, the AATF has prepared this review to highlight pathogens that are frequently resistant to licensed antimicrobials and for which few, if any, potentially effective drugs are identifiable in the late-stage development pipeline.

Safety and Potential of Drug Interactions of Caspofungin and Voriconazole in Multimorbid Patients

Due to their broad antimycotic spectrum and the relatively low rate of side effects, the two antifungals caspofungin and voriconazole are considered as attractive therapeutic alternatives to amphotericin B. However, treatment of severe mycotic infections in patients taking co-medication is associated with the risk of severe adverse drug interactions. The risk of such interactions is increased if voriconazole and, much less pronounced caspofungin, are co-administered with drugs which have an inducing or inhibiting effect on the CYP 450 system, primarily on the isoenzymes CYP2C19, CYP2C9 and CYP3A4. This review provides a comprehensive overview on the potential drug interactions of caspofungin and voriconazole in multimorbid patients.