Newer Systemic Antifungal Agents

Fungal interface keratitis by Candida orthopsilosis following deep anterior lamellar keratoplasty

A 39-year-old male patient underwent uncomplicated deep anterior lamellar keratoplasty due to keratoconus. On day 5 after surgery, small whitish infiltrates developed in the corneal interface. The diagnosis of fungal keratitis was made when the culture medium of the graft grew Candida after the surgical intervention. Despite intensive antimycotic treatment and irrigation of the interface, the infiltrates persisted and eventually enlarged. Therefore, revision surgery with penetrating keratoplasty was performed. Microbiological analysis showed Candida orthopsilosis in the culture of the excised graft button. Histopathological staining of the excised graft showed periodic acid-Schiff-positive and Grocott methenamine silver-positive clusters of yeast between Descemet's membrane and the deep corneal stroma with focal perforations through Descemet's membrane. The treatment of mycotic keratitis caused by C orthopsilosis is challenging. Antimycotic treatment was unsuccessful in this case. Progression of the keratitis and perforation of Descemet's membrane suggest that early surgical intervention by penetrating keratoplasty is required.

Overview of invasive fungal infections

The incidence of invasive fungal infections (IFIs) has seen a marked increase in the last two decades. This is especially evident among transplant recipients, patients suffering from AIDS, in addition to those in receipt of immunosuppressive therapy. Worryingly, this increased incidence includes infections caused by opportunistic fungi and emerging fungal infections which are resistant to or certainly less susceptible than others to standard antifungal agents. As a direct response to this phenomenon, there has been a resolute effort over the past several decades to improve early and accurate diagnosis and provide reliable screening protocols thereby promoting the administration of appropriate antifungal therapy for fungal infections. Early diagnosis and treatment with antifungal therapy are vital if a patient is to survive an IFI. Substantial advancements have been made with regard to both the diagnosis and subsequent treatment of an IFI. In parallel, stark changes in the epidemiological profile of these IFIs have similarly occurred, often in direct response the type of antifungal agent being administered. The effects of an IFI can be far reaching, ranging from increased morbidity and mortality to increased length hospital stays and economic burden.

[Venous catheter-related infections]

Central venous catheter-related infections can lead to a substantial increase in morbidity and mortality in patients. Nowadays, with the increase in multi-resistant bacteria, the recent appearance of new antibiotics, and the development of new treatment guidelines, means that this has to be constantly reviewed. The objective of this review is to briefly define the epidemiological and pathogenic concepts and to look in detail at the preventive and therapeutic measures of this type of infection. Practical aspects are presented of different clinical situations such as, antibiotic-lock of the central venous catheter, and the withdrawal or maintenance of the catheter.

Echinocandins: are they all the same?

The discovery of echinocandins, and their development and approval, was hailed as a significant addition to our antifungal armamentarium, previously predominated by polyenes and azoles. To date, three echinocandins (anidulafungin, caspofungin, and micafungin) have been approved by the U.S. Food and Drug Administration for the treatment of fungal infections. Since all three echinocandins target the fungal cell wall and share a similar structural chemical backbone, they are perceived to be identical. However, a scientific literature review shows distinct differences among the echinocandins in terms of in vitro activity, fungicidal activity, post-antifungal effect, paradoxical effect, and activity on biofilms. More investigation is warranted to determine if the observed differences among the echinocandins can translate to clinical advantages.

Importance of pharmacokinetic considerations for selecting therapy in the treatment of invasive fungal infections

Invasive fungal infections continue to be a significant cause of morbidity and mortality among at-risk patients. Over the last decade, the epidemiology of invasive mycoses has been defined by increasing rates of infection caused by azole-resistant yeast (Candida glabrata, Candida krusei), Aspergillus, and in some centers, non-Aspergillus moulds, such as Fusarium species, Scedosporium species, and Mucorales. Early and appropriate antifungal therapy is crucial for a favorable clinical outcome. When selecting antifungal therapy--especially during the initial acute phases of treatment--spectrum of activity and pharmacokinetic characteristics are key treatment considerations. Important pharmacokinetic considerations for selecting antifungal therapy in the treatment of invasive fungal infections include drug-drug interactions and variability in adsorption that may limit efficacy during the early phase of treatment, poor oral availability, and variable tissue distribution. A patient's underlying condition and pharmacogenetics also may affect the pharmacokinetics of antifungal drugs, resulting in interpatient pharmacokinetic differences.

A multicenter, open-label study of posaconazole oral suspension in the treatment of invasive fungal infections in patients refractory to or intolerant of first-line therapy

Aim: Invasive fungal infections pose a severe health threat to patients. Despite recent advances in drug development, treatment of recurrent fungal infections remains difficult. Posaconazole is a broad-spectrum triazole antifungal drug available for oral administration. Although initial studies have described its use in treating various fungal infections, its efficacy and safety in patients with invasive fungal infections remains to be further confirmed. Materials & Methods: In this study, we performed a multicenter, open-label clinical trial of posaconazole oral suspension in the treatment of 63 patients with invasive fungal infections who were refractory to or intolerant of first-line therapy. Results: Our result showed that 64.4% of patients had a clinical response after posaconazole treatment, with 52.9% showing eradication of the fungal infection. The treatment caused some adverse effects of mild or moderate severity that were of short duration. Conclusion: The results of this trial indicate that posaconazole can be used in invasive fungal infections as an alternative or salvage therapy.

Posaconazole: A new agent for the prevention and management of severe, refractory or invasive fungal infections

Posaconazole is the newest antifungal agent to be approved for use in Canada. With excellent in vitro activity against a broad spectrum of yeasts and filamentous fungi, as well as having a well-tolerated oral formulation, posaconazole offers many potential advantages. Of particular interest are its seemingly lower potential for cross-resistance with other azoles and its activity (unique among oral antifungal agents) against the zygomycetes. As the incidence of both common and uncommon fungal infections increases commensurate with the growing population of immunocompromised individuals, posaconazole may ultimately become an important therapeutic option. The present article reviews the in vitro and in vivo data describing its activity, and focuses on both the proven and the potential clinical applications of this new triazole agent.

Diagnosis and therapy of Candida infections: joint recommendations of the German Speaking Mycological Society and the Paul-Ehrlich-Society for Chemotherapy

Invasive Candida infections are important causes of morbidity and mortality in immunocompromised and hospitalised patients. This article provides the joint recommendations of the German-speaking Mycological Society (Deutschsprachige Mykologische Gesellschaft, DMyKG) and the Paul-Ehrlich-Society for Chemotherapy (PEG) for diagnosis and treatment of invasive and superficial Candida infections. The recommendations are based on published results of clinical trials, case-series and expert opinion using the evidence criteria set forth by the Infectious Diseases Society of America (IDSA). Key recommendations are summarised here: The cornerstone of diagnosis remains the detection of the organism by culture with identification of the isolate at the species level; in vitro susceptibility testing is mandatory for invasive isolates. Options for initial therapy of candidaemia and other invasive Candida infections in non-granulocytopenic patients include fluconazole or one of the three approved echinocandin compounds; liposomal amphotericin B and voriconazole are secondary alternatives because of their less favourable pharmacological properties. In granulocytopenic patients, an echinocandin or liposomal amphotericin B is recommended as initial therapy based on the fungicidal mode of action. Indwelling central venous catheters serve as a main source of infection independent of the pathogenesis of candidaemia in the individual patients and should be removed whenever feasible. Pre-existing immunosuppressive treatment, particularly by glucocorticosteroids, ought to be discontinued, if feasible, or reduced. The duration of treatment for uncomplicated candidaemia is 14 days following the first negative blood culture and resolution of all associated symptoms and findings. Ophthalmoscopy is recommended prior to the discontinuation of antifungal chemotherapy to rule out endophthalmitis or chorioretinitis. Beyond these key recommendations, this article provides detailed recommendations for specific disease entities, for antifungal treatment in paediatric patients as well as a comprehensive discussion of epidemiology, clinical presentation and emerging diagnostic options of invasive and superficial Candida infections.

Pharmacology and metabolism of voriconazole and Posaconazole in the treatment of invasive aspergillosis: review of the literature

Invasive fungal infections, predominantly aspergillosis and candidiasis, are among the most important causes of morbidity and mortality in immunocompromised patients. Primarily, patients with acute leukemia undergoing myelosuppressive chemotherapy and allogeneic stem cell transplant recipients are affected. Up to 60% of patients with invasive aspergillosis, the most common invasive mycosis among patients with hematologic malignancies, may still die of their infection, once it has become clinically overt. The spectrum of antifungal agents for clinical use now has expanded over the past ten years and includes the novel class of the echinocandins and two newer generation triazoles with an extended spectrum of activity against a wide range of fungal pathogens. This review will address pharmacological characteristics of the two broad-spectrum antifungal azoles, voriconazole and Posaconazole, which are important for their proper use in clinical practice.

Comparison of echinocandin antifungals

The incidence of invasive fungal infections, especially those due to Aspergillus spp. and Candida spp., continues to increase. Despite advances in medical practice, the associated mortality from these infections continues to be substantial. The echinocandin antifungals provide clinicians with another treatment option for serious fungal infections. These agents possess a completely novel mechanism of action, are relatively well-tolerated, and have a low potential for serious drug-drug interactions. At the present time, the echinocandins are an option for the treatment of infections due Candida spp (such as esophageal candidiasis, invasive candidiasis, and candidemia). In addition, caspofungin is a viable option for the treatment of refractory aspergillosis. Although micafungin is not Food and Drug Administration-approved for this indication, recent data suggests that it may also be effective. Finally, caspofungin- or micafungin-containing combination therapy should be a consideration for the treatment of severe infections due to Aspergillus spp. Although the echinocandins share many common properties, data regarding their differences are emerging at a rapid pace. Anidulafungin exhibits a unique pharmacokinetic profile, and limited cases have shown a potential far activity in isolates with increased minimum inhibitory concentrations to caspofungin and micafungin. Caspofungin appears to have a slightly higher incidence of side effects and potential for drug-drug interactions. This, combined with some evidence of decreasing susceptibility among some strains of Candida, may lessen its future utility. However, one must take these findings in the context of substantially more data and use with caspofungin compared with the other agents. Micafungin appears to be very similar to caspofungin, with very few obvious differences between the two agents.

Voriconazole in the management of nosocomial invasive fungal infections

Voriconazole is a new triazole developed for the treatment of life-threatening fungal infections. The drug is available for both oral and intravenous administration; the oral formulation has excellent bioavailability. The side-effect profile of voriconazole presents an acceptable safety and tolerability spectrum: transient visual disturbances, liver enzyme abnormalities, and skin rashes are the most frequently reported side effects but rarely lead to discontinuation. The potential for drug–drug interactions is high, because of its extensive hepatic metabolism. Careful attention to dosage is required, and serum levels and the effects of interacting drugs should be monitored. Review of 25 470 isolates of yeasts and 3216 isolates of filamentous fungi showed voriconazole to have broad-spectrum activity against pathogenic yeasts including intrinsically fluconazole-resistant isolates such as Candida krusei, dimorphic fungi, and opportunistic moulds like Aspergillus spp, amphotericin-B-resistant Aspergillus terreus, Fusarium spp, and Scedosporium apiospermum. It displays excellent clinical efficacy in patients with fluconazole-resistant and -susceptible Candida infections, invasive bone and central nervous system aspergillosis, and various refractory fungal infections. Voriconazole has been approved by the US Food and Drug Administration and by the European Medicines Agency for the treatment of invasive aspergillosis, serious infections caused by Fusarium and S. apiospermum, fluconazole-resistant invasive Candida infections, and candidemia in nonneutropenic patients.

Emerging moulds: epidemiological trends and antifungal resistance

Invasive fungal infections (IFIs) are associated with high morbidity and mortality in immunocompromised patients. Although Aspergillus spp. remain an important cause of IFI, other moulds such as Fusarium spp., dematiaceous fungi and Mucorales have become increasingly prevalent among this patient population. Diagnosis and treatment of invasive mould infections remain a challenge. Because of the poor prognosis associated with IFIs, understanding the activity, efficacy and limitations of the available drugs is critical to select the appropriate antifungal agent on an individualised basis.

Long-term visual safety of voriconazole in adult patients with paracoccidioidomycosis

BACKGROUND

Voriconazole is an antifungal agent with in vitro activity and clinical efficacy against yeasts, molds, and dimorphic fungi (eg, Paracoccidioides brasiliensis). The safety profile of voriconazole includes transient visual adverse events (VAEs) that resolve while undergoing treatment or after its discontinuation.

OBJECTIVE

The goal of this study was to assess the long-term (ie, 6-12 months) visual safety of voriconazole in adult patients with paracoccidioidomycosis.

METHODS

Ophthalmic data were prospectively collected as part of a multicenter, open-label, comparative study. Patients aged ≥18 years with paracoccidioidomycosis were randomized in a 2:1 ratio to receive either voriconazole (200 mg BID orally, after the loading dose of 400 mg BID on day 1) or itraconazole (100 mg BID orally, with no loading dose). Patients were expected to receive treatment for a minimum of 6 months, or longer if needed as determined by the investigator (maximum duration, 1 year). Visual function tests and safety assessments were performed at baseline, week 12, week 24, end of treatment (EOT), and 8 weeks post-EOT. Ophthalmic examinations included visual acuity, color vision, contrast sensitivity, visual field, funduscopy, and slit lamp biomicroscopy. Treatment compliance was monitored via pill counts at each study visit.

RESULTS

Thirty-five patients (mean age, 48 years; 96.2% male; 83.0% white) were randomized to receive voriconazole and 18 to receive itraconazole. Fourteen voriconazole-treated patients received >6 months of treatment (median, 169 days). Efficacy and overall safety results have been published previously. Sixteen voriconazole-treated patients and 2 itraconazole-treated patients experienced drug-related VAEs; none was considered serious or severe or led to dose reductions or resulted in discontinuation. Overall, visual examination results were not clinically significantly different between patients treated with voriconazole or itraconazole. There was no apparent relationship between changes in visual function test results and the occurrence of VAEs in either treatment group.

CONCLUSION

Clinical assessment in this study found no evidence of an effect of voriconazole on long-term visual function in these adult patients with paracoccidioidomycosis.

How I treat mucormycosis

Unlike invasive aspergillosis, the prognosis and outcome of hematologic malignancy patients who develop invasive mucormycosis have not significantly improved over the past decade as a majority of patients who develop the infection still die 12 weeks after diagnosis. However, early recognition and treatment of invasive mucormycosis syndromes, as well as individualized approaches to treatment and secondary prophylaxis, could improve the odds of survival, even in the most persistently immunosuppressed patient receiving chemotherapy and/or of stem cell transplantation. Herein, we describe the subtle clinical and radiographic clues that should alert the hematologist to the possibility of mucormycosis, and aggressive and timely treatment approaches that may limit the spread of infection before it becomes fatal. Hematology patients with this opportunistic infection require integrated care across several disciplines and frequently highly individualized and complex sequence of decision-making. We also offer perspectives for the use of 2 antifungals, amphotericin B products and posaconazole, with activity against Mucorales. The availability of posaconazole in an oral formulation that can be administered safely for prolonged periods makes it an attractive agent for long-term primary and secondary prophylaxis. However, serum drug concentration monitoring may be required to minimize breakthrough infection or relapsing mucormycosis associated with inadequate blood concentrations.

The increased role of non-albicans species in candidaemia: results from a 3-year surveillance study

Various studies have documented a shift in species distribution in Candida bloodstream infections (BSI), but there are little data from Southeast Asia. This study was performed to determine the species epidemiology and antifungal susceptibilities of Candida species BSI in Singapore. Candida spp. from BSI were collected from a tertiary and secondary referral hospital, and an obstetrics/paediatric hospital over a 3-year period. The most common isolates were Candida albicans (36%), Candida tropicalis (27%), Candida glabrata (16%) and Candida parapsilosis (16%). Candida parapsilosis and C. albicans were predominant in the paediatric hospital, and C. albicans and C. tropicalis predominant in the other two institutions. Candida tropicalis temporarily replaced C. albicans as the predominant strain from BSI in 2006. Overall, 87.3% of Candida isolates were susceptible to fluconazole, and 10.4% classified as susceptible-dose-dependent. Fluconazole resistance was detected in C. tropicalis (3.6%), C. parapsilosis (2.1%) and C. glabrata (4.0%). Candida albicans is the predominant species isolated from BSI in Singapore. However, non-albicans species accounted for nearly two-thirds of all cases of candidaemia and the relative increase in C. tropicalis infections deserves further investigation. Resistance to fluconazole was uncommon.

Fusarium infection in lung transplant patients: report of 6 cases and review of the literature

Fusarium is a fungal pathogen of immunosuppressed lung transplant patients associated with a high mortality in those with severe and persistent neutropenia. The principle portal of entry for Fusarium species is the airways, and lung involvement almost always occurs among lung transplant patients with disseminated infection. In these patients, the immunoprotective mechanisms of the transplanted lungs are impaired, and they are, therefore, more vulnerable to Fusarium infection. As a result, fusariosis occurs in up to 32% of lung transplant patients. We studied fusariosis in 6 patients following lung transplantation who were treated at Massachusetts General Hospital during an 8-year period and reviewed 3 published cases in the literature. Cases were identified by the microbiology laboratory and through discharge summaries. Patients presented with dyspnea, fever, nonproductive cough, hemoptysis, and headache. Blood tests showed elevated white blood cell counts with granulocytosis and elevated inflammatory markers. Cultures of Fusarium were isolated from bronchoalveolar lavage, blood, and sputum specimens.Treatments included amphotericin B, liposomal amphotericin B, caspofungin, voriconazole, and posaconazole, either alone or in combination. Lung involvement occurred in all patients with disseminated disease and it was associated with a poor outcome. The mortality rate in this group of patients was high (67%), and of those who survived, 1 patient was treated with a combination of amphotericin B and voriconazole, 1 patient with amphotericin B, and 1 patient with posaconazole. Recommended empirical treatment includes voriconazole, amphotericin B or liposomal amphotericin B first-line, and posaconazole for refractory disease. High-dose amphotericin B is recommended for treatment of most cases of fusariosis. The echinocandins (for example, caspofungin, micafungin, anidulafungin) are generally avoided because Fusarium species have intrinsic resistance to them. Treatment should ideally be based on the Fusarium isolate, susceptibility testing, and host-specific factors. Prognosis of fusariosis in the immunocompromised is directly related to a patient's immune status. Prevention of Fusarium infection is recommended with aerosolized amphotericin B deoxycholate, which also has activity against other important fungi.

Evaluation of hepatotoxicity with off-label oral-treatment doses of voriconazole for invasive fungal infections

The approved treatment dose of intravenous voriconazole is a weight-based dose of 4 mg/kg of body weight twice daily; the approved oral dosing is fixed at 200 mg twice daily. In our institution, patients frequently receive oral high-dose voriconazole at 4 mg/kg twice daily. It is unknown if higher doses are associated with increased hepatotoxicity. A retrospective cohort study of patients treated with oral voriconazole for presumed invasive fungal infection for ≥7 days was completed. Patients receiving a fixed dose (i.e., labeled dose) were frequency matched and compared to those receiving a weight-based dose (i.e., high dose). The primary endpoint of hepatotoxicity was evaluated by using NCI Common Terminology Criteria (CTC) and components of liver enzymes measuring >3× the upper limit of normal (ULN) and >5× baseline measurements. Secondary endpoints included an incidence of other adverse drug events. Twenty-five labeled-dose and 84 high-dose voriconazole patients were studied. Liver enzyme abnormalities were similar between groups, with the exception of labeled-dose patients experiencing more alkaline phosphatase (ALP) CTC >2× the baseline (P = 0.02) and ALP levels >3× the ULN (P = 0.02). Treatment with high dose was associated with the discontinuation of voriconazole for practitioner attribution of adverse drug events (P = 0.03), although reasons varied and no commonality of biomarker abnormality was identified. Multivariate analysis revealed that the duration of therapy and higher mg/kg total daily doses as interval variables were predictive of some hepatotoxicity outcomes. No difference existed in liver abnormalities for high-dose voriconazole; however, higher mg/kg doses and a longer duration of therapy may be associated with hepatotoxicity.

In vitro profiling of pramiconazole and in vivo evaluation in Microsporum canis dermatitis and Candida albicans vaginitis laboratory models

The triazole antifungal pramiconazole (Stiefel, a GSK company) was compared with itraconazole, miconazole, and terbinafine in vitro and in vivo. Potent in vitro activities against Candida spp. (50% inhibitory concentration [IC₅₀], 0.04 to 1.83 μM) and Microsporum and Trichophyton spp. (IC₅₀, 0.15 to 1.34 μM) were obtained but not, however, against other filamentous molds and zygomycetes. In the M. canis guinea pig model and C. albicans vulvovaginitis rat model, pramiconazole was superior to the reference compounds after oral and topical administration.

Pharmacokinetics, safety, and tolerability of voriconazole in immunocompromised children

The pharmacokinetics of voriconazole in children receiving 4 mg/kg intravenously (i.v.) demonstrate substantially lower plasma exposures (as defined by area under the concentration-time curve [AUC]) than those in adults receiving the same therapeutic dosage. These differences in pharmacokinetics between children and adults limit accurate prediction of pediatric voriconazole exposure based on adult dosages. We therefore studied the pharmacokinetics and tolerability of higher dosages of an i.v.-to-oral regimen of voriconazole in immunocompromised children aged 2 to <12 years in two dosage cohorts for the prevention of invasive fungal infections. The first cohort received 4 mg/kg i.v. every 12 h (q12h), then 6 mg/kg i.v. q12h, and then 4 mg/kg orally (p.o.) q12h; the second received 6 mg/kg i.v. q12h, then 8 mg/kg i.v. q12h, and then 6 mg/kg p.o. q12h. The mean values for the AUC over the dosing interval (AUCτ) for 4 mg/kg and 6 mg/kg i.v. in cohort 1 were 11,827 and 22,914 ng.h/ml, respectively, whereas the mean AUCτ values for 6 mg/kg and 8 mg/kg i.v. in cohort 2 were 17,249 and 29,776 ng.h/ml, respectively. High interpatient variability was observed. The bioavailability of the oral formulation in children was approximately 65%. The safety profiles were similar in the two cohorts and age groups. The most common treatment-related adverse event was increased gamma glutamyl transpeptidase levels. There was no correlation between adverse events and voriconazole exposure. In summary, voriconazole was tolerated to a similar degree regardless of dosage and age; the mean plasma AUCτ for 8 mg/kg i.v. in children approached that for 4 mg/kg i.v. in adults, thus representing a rationally selected dosage for the pediatric population.

Candida infections of the genitourinary tract

All humans are colonized with Candida species, mostly Candida albicans, yet some develop diseases due to Candida, among which genitourinary manifestations are extremely common. The forms of genitourinary candidiasis are distinct from each other and affect different populations. While vulvovaginal candidiasis affects mostly healthy women, candiduria occurs typically in elderly, hospitalized, or immunocompromised patients and in neonates. Despite its high incidence and clinical relevance, genitourinary candidiasis is understudied, and therefore, important questions about pathogenesis and treatment guidelines remain to be resolved. In this review, we summarize the current knowledge about genitourinary candidiasis.

Comparison of natamycin and voriconazole for the treatment of fungal keratitis

OBJECTIVE

To conduct a therapeutic exploratory clinical trial comparing clinical outcomes of treatment with topical natamycin vs topical voriconazole for fungal keratitis.

METHODS

The multicenter, double-masked, clinical trial included 120 patients with fungal keratitis at Aravind Eye Hospital in India who were randomized to receive either topical natamycin or topical voriconazole and either had repeated scraping of the epithelium or not.

MAIN OUTCOME MEASURES

The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months. Other outcomes included scar size, perforations, and a subanalysis of BSCVA at 3 months in patients with an enrollment visual acuity of 20/40 to 20/400.

RESULTS

Compared with those who received natamycin, voriconazole-treated patients had an approximately 1-line improvement in BSCVA at 3 months after adjusting for scraping in a multivariate regression model but the difference was not statistically significant (P = .29). Scar size at 3 months was slightly greater with voriconazole after adjusting for scraping (P = .48). Corneal perforations in the voriconazole group (10 of 60 patients) were not significantly different than in the natamycin-treated group (9 of 60 patients) (P >.99). Scraping was associated with worse BSCVA at 3 months after adjusting for drug (P = .06). Patients with baseline BSCVA of 20/40 to 20/400 showed a trend toward a 2-line improvement in visual acuity with voriconazole (P = .07).

CONCLUSIONS

Overall, there were no significant differences in visual acuity, scar size, and perforations between voriconazole- and natamycin-treated patients. There was a trend toward scraping being associated with worse outcomes. Application to Clinical Practice The benefit seen with voriconazole in the subgroup of patients with baseline visual acuity of 20/40 to 20/400 needs to be validated in a confirmatory clinical trial. Trial Registration clinicaltrials.gov Identifier: NCT00557362.

Pharmacoeconomics of voriconazole

IMPORTANCE OF THE FIELD

The recent increase in the use of antineoplastic and immune suppressive agents and the use of broad-spectrum antibiotics, prosthetic interventions, organ transplants and more aggressive surgery have been related to a greater prevalence of invasive fungal infections (IFI). Over the past few years, several new antifungal therapies have become available for these patients. Pharmacoeconomic data can play a useful role in comparing the relative benefits of treatment.

AREAS COVERED IN THIS REVIEW

This review summarizes all the available evidence regarding the pharmacoeconomics of voriconazole. A systematic review of pharmacoeconomic analyses through a non-restricted literature search was conducted (until May 2009).

WHAT THE READER WILL GAIN

The reader will gain a greater understanding of the pharmacoeconomics role of voriconazole.

TAKE HOME MESSAGE

The majority of economic analyses have shown that voriconazole is a more cost-effective alternative in the treatment of invasive fungal infections than the antifungal drugs with which it was compared.

Pharmacokinetics of voriconazole after oral administration of single and multiple doses in Hispaniolan Amazon parrots (Amazona ventralis)

OBJECTIVE

To determine the pharmacokinetics and safety of voriconazole administered orally in single and multiple doses in Hispaniolan Amazon parrots (Amazona ventralis).

ANIMALS

15 clinically normal adult Hispaniolan Amazon parrots.

PROCEDURES

Single doses of voriconazole (12 or 24 mg/kg) were administered orally to 15 and 12 birds, respectively; plasma voriconazole concentrations were determined at intervals via high-pressure liquid chromatography. In a multiple-dose trial, voriconazole (18 mg/kg) or water was administered orally to 6 and 4 birds, respectively, every 8 hours for 11 days (beginning day 0); trough plasma voriconazole concentrations were evaluated on 3 days. Birds were monitored daily, and clinicopathologic variables were evaluated before and after the trial.

RESULTS

Voriconazole elimination half-life was short (0.70 to 1.25 hours). In the single-dose experiments, higher drug doses yielded proportional increases in the maximum plasma voriconazole concentration (C(max)) and area under the curve (AUC). In the multiple-dose trial, C(max), AUC, and plasma concentrations at 2 and 4 hours were decreased on day 10, compared with day 0 values; however, there was relatively little change in terminal half-life. With the exception of 1 voriconazole-treated parrot that developed polyuria, adverse effects were not evident.

CONCLUSIONS AND CLINICAL RELEVANCE

In Hispaniolan Amazon parrots, oral administration of voriconazole was associated with proportional kinetics following administration of single doses and a decrease in plasma concentration following administration of multiple doses. Oral administration of 18 mg of voriconazole/kg every 8 hours would require adjustment to maintain therapeutic concentrations during long-term treatment. Safety and efficacy of voriconazole treatment in this species require further investigation.

Drug interactions and adverse events associated with antimycotic drugs used for invasive aspergillosis in hematopoietic SCT

The aim of this study was to assess the frequency of potential drug-drug interactions (pDDIs) and adverse drug events (ADEs) associated with antimycotics in hospitalized patients with hematopoietic SCT (HSCT). Of the 120 HSCT recipients evaluated, 36 received antimycotics. A total of 124 ADEs were recorded in 32 of the 36 patients treated, with 54 ADEs being possibly and 9 probably related to antimycotics. Of the treatments with amphotericin B, 93% were associated with one or more possible and 36% with probable ADEs. The corresponding figures for lipid-based amphotericin B were 100% and 7%, for voriconazole 68% and 11% and for caspofungin 70% and 0%. A total of 57 potentially severe DDIs associated with antimycotics were detected in 31 of the 36 patients. Of these, 14 DDIs were a possible cause of an ADE and 5 (4 times a combination of voriconazole with CYA and once a combination of CYA with conventional amphotericin B) were probably related. Although the prevalence of pDDIs and ADEs is high in HSCT patients, ADEs related with a high probability to treatment with antimycotics are rare. Regarding the high prevalence of pDDIs, our findings underscore the importance of close monitoring of laboratory and clinical parameters, as well as dose adjustment for critical drugs, in patients with HSCT.

Antibacterial and anticandidal screening of Tunisian Citrullus colocynthis Schrad. from Medenine

ETHNOPHARMACOLOGICAL RELEVANCE

Resistance to current antibacterial drugs and the rise of opportunistic fungal infections are growing global concerns. Traditional medicine is a potential source of new antibacterials and antifungals. Citrullus colocynthis Schrad. (Cucurbitaceae) endemic in Southern Tunisia, is used in folk medicine against dermatological, gynaecological and pulmonary infections.

AIM OF STUDY

To assess in vitro antibacterial and anticandidal activity of aqueous and diluted acetone extracts of Citrullus colocynthis Schrad. MIC and MBC/MFC were determined for plant organs at different maturation stages.

MATERIALS AND METHODS

Citrullus colocynthis Schrad. was harvested and its identification was verified. Aqueous and diluted acetone extracts (from the plant's roots, stems, leaves and three maturation stages of its fruit and seeds) were screened for activity against Gram-negative and Gram-positive bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis)-and various Candida spp. (Candida glabrata, Candida albicans, Candida parapsilosis and Candida kreusei).

RESULTS

All extracts showed activity against all strains. The highest MICs and MBCs/MFCs were obtained from the fruit aqueous extracts (MIC 0.10mg/ml against Candida albicans and Candida glabrata, 0.20mg/ml against Escherichia coli and Pseudomonas aeruginosa), lowest activity from the root extracts.

CONCLUSIONS

Citrullus colocynthis Schrad. shows antibacterial and anticandidal properties. The folk medicinal use as a broad-spectrum antimicrobial agent is validated.

Economic evaluation of voriconazole versus caspofungin for the treatment of invasive aspergillosis in Belgium

OBJECTIVE

To perform an economic evaluation of voriconazole versus caspofungin in first line treatment of invasive aspergillosis (IA). These 2 antifungal drugs have a more favorable toxicity profile than the conventional amphotericin B and have a lower cost than the expensive liposomal/lipid formulation of amphotericin B. No head-to-head comparative study was conducted with voriconazole and caspofungin in IA. Based on the clinical trials of both antifungals, a conservative approach of similar efficacy has been considered.

METHODS

The analysis is based on a simplified cost-minimization model with results from the National Health system RIZIV/INAMI perspective (year 2008). Only limited direct costs were considered, namely the drug cost over the episode of treatment.Treatment duration and patients' weight were key parameters. Their values were obtained from the Belgian observational VORIBEL study (Pfizer data on file) for voriconazole treatment. Treatment duration for caspofungin was derived from the EORTC study where almost 50% of the patients were recruited in Belgian centres. Mean cost and incremental cost were calculated. Univariate sensitivity analyses were carried out on weight, treatment duration as well as on route of administration.

RESULTS

In invasive aspergillosis, the weighted cost per episode of fungal infection was 11.996 pound with voriconazole treatment (voriconazole IV followed by oral voriconazole) and 13.657 pound with caspofungin treatment (intravenous caspofungin only). The incremental saving with voriconazole treatment was 1.661 pound per patient.The cost-saving results of voriconazole were confirmed with varying treatment duration within realistic range. 41% of the patients in the VORIBEL study were fully treated with oral formulation. For these patients a saving of 6.375 pound was achieved with the use of oral voriconazole.

CONCLUSION

Voriconazole is a cost-saving option compared with caspofungin in the treatment of invasive aspergillosis.

[Role of anidulafungin in critically ill patients]

The most frequent invasive fungal infections in critically ill patients are invasive candidiasis, among which is candidemia. In the last few years, these infections have become more common in intensive care units (ICU), including those produced by species other than Candida albicans. This phenomenon may lead to the development of species resistant to antifungal agents. To start the most appropriate treatment, early diagnosis of the infection is essential, which would reduce empirical antibiotic treatment and increase the proportion of advanced or directed antibiotic therapy. Given the poor reliability of the available diagnostic techniques, new strategies are currently being employed in the ICU, such as the use of scores to evaluate the presence of fungal infections. The therapeutic arsenal against these infections has been increased and the introduction of anidulafungin represents the addition of a highly appropriate drug for the treatment of invasive candidiasis in immunocompetent critically ill patients.

Management of invasive aspergillosis in patients with COPD: rational use of voriconazole

Invasive pulmonary aspergillosis (IPA) is an important cause of mortality in patients with hematologic malignancies. The reported incidence of IPA in the context of chronic obstructive pulmonary disease (COPD) seems to increase. Approximately 1%-2% of overall fatal cases of IPA occur in COPD patients. The combination of factors such as lung immune imbalance, long-term corticosteroid use, increasing rate of bacterial exacerbations over time, and malnutrition are responsible for the emergence of IPA in these patients. The diagnosis of IPA is difficult to establish, which explains the delay in implementing accurate antifungal therapy and the high mortality rate. Persistent pneumonia nonresponsive to appropriate antibiotic treatment raises the concern of an invasive fungal infection. Definite diagnosis is obtained from tissue biopsy evidencing Aspergillus spp. on microscopic examination or in culture. Culture and microscopy of respiratory tract samples have a sensitivity and specificity of around 50%. Other diagnostic tools can be useful in documenting IPA: computed tomography (CT) scan, nonculture-based tests in serum and/or in bronchoalveolar lavage such as antibody/antigen tests for Aspergillus spp. More recent tools such as polymerase chain reaction or [1-->3]-beta-D-glucan have predictive values that need to be further investigated in COPD patients. Antifungal monotherapy using azole voriconazole is recommended as a first-line treatment of IPA. This review assesses the use of voriconazole in COPD patients.

Voriconazole-induced phototoxicity masquerading as chronic graft-versus-host disease of the skin in allogeneic hematopoietic cell transplant recipients

Systemic fungal infections pose a significant risk to patients following allogeneic hematopoietic cell transplantation (alloHCT). Voriconazole (Vfend, Pfizer) is an oral second-generation triazole antifungal agent that offers a broad spectrum of coverage against fungal species and is frequently utilized in the post-HCT setting. Herein, we describe 5 patients who were initially believed to be experiencing a flare of cutaneous chronic graft-versus-host disease (cGVHD), but who were actually exhibiting phototoxicity caused by voriconazole. A high index of suspicion for this adverse reaction in the post-alloHCT setting will prevent misdiagnosis and avoid inappropriate therapy for cGVHD.

Approaches to the Management of Invasive Fungal Infections in Hematologic Malignancy and Hematopoietic Cell Transplantation

Patients with hematologic malignancy and hematopoietic cell transplant (HCT) recipients are at increased risk for invasive fungal infection (IFI) as a result of immunosuppression or organ damage stemming from their underlying disease, its treatment, or both. Such IFIs can cause significant morbidity and mortality, and the diagnosis and treatment of infected patients frequently are clinically challenging. This article discusses the epidemiology and risk factors for IFI in patients with hematologic malignancy and HCT recipients. The pros and cons of available antifungal agents are discussed, and evolving treatment strategies and recent prophylaxis guidelines from various professional organizations are reviewed. Finally, recommendations are offered for antifungal prophylaxis according to risk group.

Successful treatment of Candida parapsilosis (fluconazole-resistant) osteomyelitis with caspofungin in a HIV patient

Treating Candida arthritis is challenging. We report a case of Candida parapsilosis arthritis successfully treated with caspofungin. We illustrate the likelihood of severe infections due fluconazole resistant C. parapsilosis after extensive fluconazole use and discuss the role of newer antifungal agents in the treatment of arthritis due to Candida spp.

Efficacy and toxicity of intermediate-dose amphotericin B lipid complex as a primary or salvage treatment of fungal infections in patients with hematological malignancies

We treated 74 adults with a hematological malignancy and documented or suspected invasive fungal infection (IFI) with amphotericin B lipid complex (ABLC) at 3 mg/kg/day. Forty-five patients (61%) received upfront therapy and 29 patients (39%) received salvage therapy for their IFI. Forty-eight of 71 evaluable patients responded [complete responses in 40 (56%) and partial responses in 8 (11%)] and 15 (21%) died as a consequence of the IFI. Response rates in invasive aspergillosis were 33 out of 49 (67%) for probable/definite cases and 6 out of 11 (55%) for invasive candidiasis. In 40 patients with neutropenia-associated IFI, rapid neutropenic recovery ( < 10 days from study entry) was essential for response to therapy (90% vs. 32%, P < 0.01). Treatment was well tolerated, with 15% infusions followed by infusion-related adverse events, nephrotoxicity in 7% of patients and 11% of withdrawals due to toxicity. These data suggest that intermediate-doses of ABLC may be of similar efficacy than higher doses with less toxicity, making it a cost-effective alternative worthy of study in future trials.

The reformulation of amphotericin B for oral administration to treat systemic fungal infections and visceral leishmaniasis

Amphotericin B (AmB) is a parenterally administered broad-spectrum antifungal and leishmanicidal drug that has been on the market for over sixty years. Unfortunately, significant infusion-related side effects and renal toxicity often accompany treatment, limiting its clinical applications. Lipid-based formulations have somewhat ameliorated the associated toxicity, but the increased cost of formulations restricts widespread use. AmB is amphipathic and exhibits low solubility and permeability, resulting in negligible absorption when administered orally. Advances in drug delivery systems have overcome some of the solubility issues that prevent oral bioavailability and new formulations are currently in development. The existence of an effective, safe and inexpensive oral formulation of amphotericin B would have significant applications for the treatment of disseminated fungal infections and would dramatically expand access to treatment of visceral leishmaniasis by introducing a readily available highly tolerated oral formulation of a drug with known efficacy.