Safety, tolerability, and pharmacokinetics of Micafungin (FK463) in febrile neutropenic pediatric patients

Antifungal agents for the treatment of systemic fungal infections in children

Traditionally, the mainstay of systemic antifungal therapy has been amphotericin B deoxycholate (conventional amphotericin B). Newer agents have been developed to fulfill special niches and to compete with conventional amphotericin B by virtue of having more favourable toxicity profiles. Some agents have displaced conventional amphotericin B for the treatment of specific fungal diseases. For example, voriconazole has emerged as the preferred treatment for invasive pulmonary aspergillosis. This notwithstanding, conventional amphotericin B remains a useful agent for the treatment of paediatric fungal infections. Knowledge of the characteristics of the newer agents is important, given the increasing numbers of patients who are being treated with these drugs. Efforts need to be directed at research aimed at generating paediatric data where these are lacking. The antifungal agents herein described are most often used as monotherapy regimens because there is no uniform consensus on the value of combination therapy, except for specific scenarios.

Micafungin: a brief review of pharmacology, safety, and antifungal efficacy in pediatric patients

Invasive fungal infections are a major cause of morbidity and mortality in children with hematological malignancies and those undergoing allogeneic hematopoietic stem-cell transplantation (HSCT). Although several new antifungal compounds recently became available, some are not yet approved for the use in the pediatric population. Among the new class of echinocandins, micafungin has been licensed in Europe and Japan for children including neonates. Because micafungin is well tolerated and exhibits few clinical relevant drug-drug interactions, the compound is of particular interest for prophylaxis and treatment of invasive mycoses in pediatric patients with cancer or following allogeneic HSCT. This review will focus on the currently available pediatric data of micafungin with emphasis on pharmacokinetics, efficacy, and safety.

Randomized comparison of safety and pharmacokinetics of caspofungin, liposomal amphotericin B, and the combination of both in allogeneic hematopoietic stem cell recipients

The combination of liposomal amphotericin B (LAMB) and caspofungin (CAS) holds promise to improve the outcome of opportunistic invasive mycoses with poor prognosis. Little is known, however, about the safety and pharmacokinetics of the combination in patients at high risk for these infections. The safety and pharmacokinetics of the combination of LAMB and CAS were investigated in a risk-stratified, randomized, multicenter phase II clinical trial in 55 adult allogeneic hematopoietic stem cell recipients (aHSCT) with granulocytopenia and refractory fever. The patients received either CAS (50 mg/day; day 1, 70 mg), LAMB (3 mg/kg of body weight/day), or the combination of both (CASLAMB) until defervescence and granulocyte recovery. Safety, development of invasive fungal infections, and survival were assessed through day 14 after the end of therapy. Pharmacokinetic sampling and analysis were performed on days 1 and 4. All three regimens were well tolerated. Premature study drug discontinuations due to grade III/IV adverse events occurred in 1/18, 2/20, and 0/17 patients randomized to CAS, LAMB, and CASLAMB, respectively. Adverse events not leading to study drug discontinuation were frequent but similar across cohorts, except for a higher frequency of hypokalemia with CASLAMB (P < 0.05). Drug exposures were similar for patients receiving combination therapy and those randomized to monotherapy. There was no apparent difference in the occurrence of proven/probable invasive fungal infections and survival through day 14 after the end of therapy. CASLAMB combination therapy in immunocompromised aHSCT patients was as safe as monotherapy with CAS or LAMB and had similar plasma pharmacokinetics, lending support to further investigations of the combination in the management of patients with invasive opportunistic mycoses.

Candidemia in children

Seriously ill or immunocompromised children are at increased risk of invasive fungal infections, particularly candidemia. Candida albicans and Candida parapsilosis are the two most frequent causes of candidemia in pediatric patients. Candidemia in children is associated with high morbidity and mortality, increased length of hospital stays, and higher healthcare costs. Early effective antifungal therapy is the key to improved outcomes. Risk factors for candidemia may be used to identify patients suitable for empiric therapy. Such risk factors include prolonged stay in an intensive care unit, immunosuppression, prior bacterial infection, and recent surgery, as well as the use of a central venous catheter, mechanical ventilation, and/or total parenteral nutrition. Recent guidelines from the Infectious Diseases Society of America recommend consideration of fluconazole or an echinocandin for empiric therapy in suitable candidates, with a preference for an echinocandin in patients with moderate-to-severe disease, recent azole exposure, or high risk of Candida glabrata or Candida krusei infection. Fluconazole or an echinocandin is also preferred initial therapy for non-neutropenic candidemia, depending on disease severity and other characteristics. The guidelines recommend treatment with an echinocandin or lipid formulation of amphotericin B for most patients with neutropenic candidemia, although fluconazole is identified as an alternative for less critically ill patients without recent azole exposure. Risk factors for candidemia - and, hence, criteria for prophylaxis - are less well established in older children than in neonates. Further research is needed to better establish criteria for antifungal prophylaxis in children at high risk for candidemia.

Population pharmacokinetics of micafungin in neonates and young infants

Micafungin is an echinocandin with potent activity against Candida spp. Hematogenous Candida meningoencephalitis (HCME) is a frequent complication of disseminated Candida infection in premature infants. A preclinical model of HCME suggests that micafungin may be an effective agent for this syndrome, but relatively high weight-based dosages are required. This prompted the further study of the safety and pharmacokinetics (PK) of micafungin in infants. Here, we describe the population pharmacokinetics of micafungin in 47 infants with a proven or presumptive diagnosis of disseminated candidiasis, who received 0.75, 1.5, 3, 7, 10, and 15 mg/kg of micafungin. The drug was infused daily, and samples were taken in the first dosing interval and at steady state. Serum concentrations were measured using high-performance liquid chromatography (HPLC). Data were modeled using an allometric pharmacokinetic model using a three-fourths scaling exponent for clearance and parameters normalized to a 70-kg adult. Drug exposures were estimated using Monte Carlo simulation. Optimal sampling times were determined using D-optimal design theory. The fit of the allometric model to the data was highly acceptable. The pharmacokinetics of micafungin were linear. The weight-normalized estimates of clearance and volume of distribution approximated those previously described for adults. The original population parameter values could be recapitulated in the Monte Carlo simulations. A dosage of 10 mg/kg/day resulted in 82.6% of patients with areas under the concentration-time curve (AUCs) that are associated with near-maximal decline in fungal burden within the central nervous system (CNS).

Pediatric antifungal agents

PURPOSE OF REVIEW

In immunocompromised hosts, invasive fungal infections are common and fatal. In the past decade, the antifungal armamentarium against invasive mycoses has expanded greatly. The purpose of the present report is to review the most recent literature addressing the use of antifungal agents in children.

RECENT FINDINGS

Most studies evaluating the safety and efficacy of antifungal agents are limited to adults. However, important progress has been made in describing the pharmacokinetics and safety of newer antifungal agents in children, including the echinocandins.

SUMMARY

Dosage guidelines for newer antifungal agents are currently based on adult and limited pediatric data. Because important developmental pharmacology changes occur throughout childhood impacting the pharmacokinetics of these agents, antifungal studies specifically designed for children are necessary.

A Clinical Review of Echinocandins in Pediatric Patients

OBJECTIVE

To identify and evaluate available data on pediatric echinocandin use.

DATA SOURCES

A PubMed search, limited to English-language articles, was conducted (1990-August 2009) using the search terms echinocandin, pediatric, child, pharmacokinetics, caspofungin, micafungin, and anidulafungin. Additional articles were retrieved from citations of selected references.

STUDY SELECTION AND DATA EXTRACTION

Relevant information on the pharmacology, pharmacokinetics, efficacy, and safety of echinocandins in children was selected. Clinical trials, retrospective reviews, and case series were identified and evaluated. Data from these sources were included in this review.

DATA SYNTHESIS

Caspofungin is the only echinocandin approved by the Food and Drug Administration for use in children. Pediatric pharmacokinetics has been evaluated with all 3 echinocandins but is limited with anidulafungin. Micafungin is the most well-studied agent in prospective clinical trials for antifungal prophylaxis in stem cell transplantation and treatment of invasive fungal infections. Caspofungin has been studied prospectively for febrile neutropenia and treatment of invasive fungal infections, but most published data are from retrospective reviews or case reports. One case report of anidulafungin for neonatal candidiasis has been published. The role of echinocandins in the management of invasive pediatric fungal infections has expanded. Micafungin and caspofungin are recommended as primary or alternative treatment of candidemia and esophageal or invasive candidiasis, and as salvage therapy for invasive aspergillosis. Micafungin is recommended for neutropenic prophylaxis in stem cell transplantation, while caspofungin may be used in febrile neutropenia as an alternative to azoles. Dosing has been well established for caspofungin only in children 3 months of age and above. Anidulafungin should be avoided in children until more pharmacokinetic and clinical data become available.

CONCLUSIONS

Further comparative trials are needed to more clearly define the role of echinocandins, either as monotherapy or in combination for difficult-to-treat infections, in the pediatric population.

Review of the pharmacology and clinical studies of micafungin

Micafungin, like other members of the echinocandin class, has a unique mechanism of action that inhibits the synthesis of 1,3-β-D glucans in the fungal cell wall. It has been approved for treatment of esophageal candidiasis, invasive candidiasis including candidemia, and for prophylaxis of Candida infections in patients undergoing hematopoietic stem cell transplantation. Although efficacy and safety have also been demonstrated in pediatric populations, micafungin is approved for this indication in Europe and Japan, but not in the United States. It has demonstrated activity against Candida spp. including those that are azole-resistant as well as Aspergillus and a few other clinically important molds. It is administered intravenously as a once daily infusion and does not require dose adjustments for renal or moderate hepatic dysfunction. Its safety record, favorable tolerability profile, and few drug interactions make it an important agent for the treatment of invasive fungal infections.

Micafungin concentrations from brain tissue and pancreatic pseudocyst fluid

We report the attainment of micafungin concentrations from brain tissue and pancreatic pseudocyst fluid from two patients with invasive candidiasis. Micafungin was present in low levels at both body sites, indicating limited penetration into central nervous system (CNS) tissue and pancreatic fluid. Further studies are needed to fully characterize its pharmacokinetics at these locations, as micafungin may potentially serve as an alternative antifungal therapy for CNS or pancreatic candidal infections for which the currently recommended first-line therapy fails.

Safety and pharmacokinetics of repeat-dose micafungin in young infants

Given the risk of central nervous system infection, relatively high weight-based echinocandin dosages may be required for the successful treatment of invasive candidiasis and candidemia in young infants. This open-label study assessed the safety and pharmacokinetics (PK) of micafungin in 13 young infants (>48 h and <120 days of life) with suspected candidemia or invasive candidiasis. Infants of body weight > or =1,000 and <1,000 g received 7 and 10 mg/kg/day, respectively, for a minimum of 4-5 days. In the 7-mg/kg/day group, the mean baseline weight and gestational age were 2,101 g and 30 weeks, respectively; in the 10-mg/kg/day group, they were 688 g and 25 weeks, respectively. The median pharmacokinetic values for the 7- and 10-mg/kg/day groups, respectively, were as follows: area under the concentration-time curve from 0 to 24 h (AUC(0-24)), 258.1 and 291.2 microg x h/ml; clearance at steady state adjusted for body weight, 0.45 and 0.57 ml/min/kg; maximum plasma concentration, 23.3 and 24.9 micro g/ml; and volume of distribution at steady state adjusted for body weight, 341.4 and 542.8 ml/kg. No deaths or discontinuations from treatment occurred. These data suggest that micafungin dosages of 7 and 10 mg/kg/day are well tolerated and provide exposure levels that have been shown (in animal models) to be adequate for central nervous system coverage.

Antifungal prophylaxis with micafungin in patients treated for childhood cancer

BACKGROUND

Invasive fungal infections (IFIs) remain a major cause of infectious morality in neutropenic patients receiving chemotherapy or hematopoietic stem cell transplantation (HSCT). Micafungin exhibits broad antifungal activity against both Aspergillus and Candida species. We performed a retrospective study to determine the efficacy and safety of prophylactic micafungin against IFI in pediatric neutropenic patients during chemotherapy or HSCT.

PROCEDURE

Forty patients were given micafungin (3 mg/kg/day) intravenously for neutropenia: 131 patient-cycles (39 patients) after chemotherapy and 15 patient-cycles (14 patients) after HSCT. Median duration of neutropenia and micafungin prophylaxis was 13 and 23 days after chemotherapy and HSCT, respectively.

RESULTS

Treatment success rate, defined as absence of proven, probable, possible, or suspected IFIs, was 93.9% (121/131) and 80.0% (12/15) for chemotherapy and HSCT, respectively. Proven or probable IFI was documented in only one patient after HSCT. No adverse events were observed that could be related to micafungin prophylaxis.

CONCLUSIONS

These results suggest that prophylactic micafungin is well tolerated and may prevent IFIs in pediatric patients with neutropenia receiving chemotherapy or HSCT.

Micafungin: a review of its use in the prophylaxis and treatment of invasive Candida infections in pediatric patients

Intravenous micafungin (Mycamine; Funguard) is an echinocandin indicated in Japan and the EU for the treatment of pediatric patients (including neonates) with invasive candidiasis and as prophylaxis against Candida infection in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). In the EU, micafungin is also indicated in pediatric patients who are expected to have neutropenia for >/=10 days. In Japan, children may also receive micafungin for the treatment of, or as prophylaxis against, invasive Aspergillus infection. Micafungin is not currently approved for use in pediatric patients in the US. Micafungin has very good antifungal activity against a wide range of Candida spp. in vitro. It has a favorable pharmacokinetic profile allowing for once-daily administration, has few drug-drug interactions, and reports of resistance are rare. The results of pediatric substudies indicate that intravenous micafungin is effective in a majority of patients for the treatment of candidemia and other types of invasive candidiasis, and provides effective prophylaxis against invasive fungal infections in pediatric patients undergoing HSCT. The tolerability profile of micafungin in pediatric patients was generally acceptable. In the EU, micafungin is indicated for use when other antifungal medications are not appropriate. Therefore, micafungin provides an alternative to other antifungal agents used in the management of candidemia and invasive candidiasis in pediatric patients, or as prophylaxis against fungal infections in pediatric patients undergoing HSCT.

Guidelines for the Prevention and Treatment of Opportunistic Infections among HIV-exposed and HIV-infected children: recommendations from CDC, the National Institutes of Health, the HIV Medicine Association of the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the American Academy of Pediatrics

This report updates and combines into one document earlier versions of guidelines for preventing and treating opportunistic infections (OIs) among HIV-exposed and HIV-infected children, last published in 2002 and 2004, respectively. These guidelines are intended for use by clinicians and other health-care workers providing medical care for HIV-exposed and HIV-infected children in the United States. The guidelines discuss opportunistic pathogens that occur in the United States and one that might be acquired during international travel (i.e., malaria). Topic areas covered for each OI include a brief description of the epidemiology, clinical presentation, and diagnosis of the OI in children; prevention of exposure; prevention of disease by chemoprophylaxis and/or vaccination; discontinuation of primary prophylaxis after immune reconstitution; treatment of disease; monitoring for adverse effects during treatment; management of treatment failure; prevention of disease recurrence; and discontinuation of secondary prophylaxis after immune reconstitution. A separate document about preventing and treating of OIs among HIV-infected adults and postpubertal adolescents (Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents) was prepared by a working group of adult HIV and infectious disease specialists. The guidelines were developed by a panel of specialists in pediatric HIV infection and infectious diseases (the Pediatric Opportunistic Infections Working Group) from the U.S. government and academic institutions. For each OI, a pediatric specialist with content-matter expertise reviewed the literature for new information since the last guidelines were published; they then proposed revised recommendations at a meeting at the National Institutes of Health (NIH) in June 2007. After these presentations and discussions, the guidelines underwent further revision, with review and approval by the Working Group, and final endorsement by NIH, CDC, the HIV Medicine Association (HIVMA) of the Infectious Diseases Society of America (IDSA), the Pediatric Infectious Disease Society (PIDS), and the American Academy of Pediatrics (AAP). The recommendations are rated by a letter that indicates the strength of the recommendation and a Roman numeral that indicates the quality of the evidence supporting the recommendation so readers can ascertain how best to apply the recommendations in their practice environments. An important mode of acquisition of OIs, as well as HIV infection among children, is from their infected mother; HIV-infected women coinfected with opportunistic pathogens might be more likely than women without HIV infection to transmit these infections to their infants. In addition, HIV-infected women or HIV-infected family members coinfected with certain opportunistic pathogens might be more likely to transmit these infections horizontally to their children, resulting in increased likelihood of primary acquisition of such infections in the young child. Therefore, infections with opportunistic pathogens might affect not just HIV-infected infants but also HIV-exposed but uninfected infants who become infected by the pathogen because of transmission from HIV-infected mothers or family members with coinfections. These guidelines for treating OIs in children therefore consider treatment of infections among all children, both HIV-infected and uninfected, born to HIV-infected women. Additionally, HIV infection is increasingly seen among adolescents with perinatal infection now surviving into their teens and among youth with behaviorally acquired HIV infection. Although guidelines for postpubertal adolescents can be found in the adult OI guidelines, drug pharmacokinetics and response to treatment may differ for younger prepubertal or pubertal adolescents. Therefore, these guidelines also apply to treatment of HIV-infected youth who have not yet completed pubertal development. Major changes in the guidelines include 1) greater emphasis on the importance of antiretroviral therapy for preventing and treating OIs, especially those OIs for which no specific therapy exists; 2) information about the diagnosis and management of immune reconstitution inflammatory syndromes; 3) information about managing antiretroviral therapy in children with OIs, including potential drug--drug interactions; 4) new guidance on diagnosing of HIV infection and presumptively excluding HIV infection in infants that affect the need for initiation of prophylaxis to prevent Pneumocystis jirovecii pneumonia (PCP) in neonates; 5) updated immunization recommendations for HIV-exposed and HIV-infected children, including hepatitis A, human papillomavirus, meningococcal, and rotavirus vaccines; 6) addition of sections on aspergillosis; bartonella; human herpes virus-6, -7, and -8; malaria; and progressive multifocal leukodystrophy (PML); and 7) new recommendations on discontinuation of OI prophylaxis after immune reconstitution in children. The report includes six tables pertinent to preventing and treating OIs in children and two figures describing immunization recommendations for children aged 0--6 years and 7--18 years. Because treatment of OIs is an evolving science, and availability of new agents or clinical data on existing agents might change therapeutic options and preferences, these recommendations will be periodically updated and will be available at http://AIDSInfo.nih.gov.

Echinocandins: The Newest Class of Antifungals

Objective:

To review the mechanism of action, antifungal spectrum of activity, pharmacodynamics, pharmacokinetics, clinical efficacy, and safety of the echinocandins.

Data Sources:

A MEDLINE search (1982–May 2009) was conducted for articles published in the English language using the key words caspofungin, micafungin, anidulafungin, and echinocandins.

Study Selection and Data Extraction:

Medicinal chemistry, in vitro, and animal studies, as well as human trials were reviewed for information on the pharmacodynamics, pharmacokinetics, efficacy, and safety of each echinocandin. Clinical trials were reviewed and included to compare and contrast the available echinocandins.

Data Synthesis:

Three echinocandin antifungal agents are currently approved for use in the US: caspofungin, micafungin, and anidulafungin. The echinocandins have a unique mechanism of action, inhibiting β-(1,3)-d-glucan synthase, an enzyme that is necessary for the synthesis of an essential component of the cell wall of several fungi. The echinocandins display fungistatic activity against Aspergillus spp. and fungicidal activity against most Candida spp., including strains that are fluconazole-resistant. The echinocandins have been shown to be efficacious for the treatment of esophageal candidiasis, candidemia, and invasive candidiasis. In addition, caspofungin has demonstrated efficacy as empiric treatment of febrile neutropenia and salvage therapy for the treatment of invasive aspergillosis, and it is the only echinocandin approved for use in pediatric patients. Micafungin is the only echinocandin approved for use as prophylaxis against Candida infections in patients undergoing hematopoietic stem cell transplantation. Overall, resistance to echinocandins is still rare, and all agents are well tolerated, with similar adverse effect profiles and few drug–drug interactions.

Conclusions:

Echinocandins, the newest addition to the arsenal of antifungals, offer potential advantages over other classes of agents. Clinicians should assess their distinguishing characteristics, including route of metabolism, drug interaction profile, and approved indications for use, when determining which agent to include on a formulary.

Pharmacokinetics of prophylactic micafungin in very-low-birth-weight infants

We evaluated the use of micafungin as a prophylaxis in very-low-birth-weight infants. Micafungin was first administered to 25 very-low-birth-weight infants 12 to 24 hours after birth at a dose of 1 mg/kg/d. the apparent volume of distribution, the apparent elimination rate constant, the elimination half-life, and the total body clearance (mean +/- SD) were 0.76 +/- 0.28 L/kg, 0.12 +/- 0.041 1/h, 6.7 +/- 2.2 h, and 0.089 +/- 0.047 L/kg/h, respectively.

Pharmacotherapy of Candida Infections with Echinocandins

The classic recommended antifungal agents for the treatment of invasive Candida infections were amphotericin B, a lipid formulation of amphotericin B and fluconazole in both neutropenic or nonneutropenic patients as either primary or alternative therapies. Voriconazole has been recommended when additional coverage for filamentous fungi is needed (e.g. neutropenic patients). More recently and based on well designed comparative clinical trials, the three echinocandins, caspofungin, anidulafungin and micafungin have been added as primary or alternative therapies especially for critically ill or neutropenic patients. In general, the echinocandins are most useful when patients have previously been exposed to an azole or are unstable.

Overview of the changing epidemiology of candidemia

Candida spp. are currently the fourth most common cause of bloodstream infections in US hospitals, and the third most common cause of bloodstream infections in the intensive care unit. Over the last 2 decades there has been a shift towards a greater involvement of non-Candida albicans spp. as the cause of candidemia. Several of these non-albicans spp. (e.g., C. glabrata and C. krusei ) exhibit resistance to traditional triazole antifungals like fluconazole, and cross-resistance with newer triazoles, focusing attention on the first-line use of antifungals such as the echinocandins, which possess improved activity against fluconazole-resistant strains. Recent treatment guidelines from the Infectious Diseases Society of America (IDSA) recommend an echinocandin as primary therapy for nonneutropenic or neutropenic patients with moderately severe to severe candidiasis and for patients at risk for infection with a triazole-resistant strain. However, further improvement in candidemia-associated mortality will only be attainable with the development and validation of new diagnostic tools that will allow earlier detection, discrimination, and treatment of invasive candidiasis. Clinicians should remain vigilant to wider emergence of Candida spp. with echinocandin resistance.

Recent advances in the management of mucormycosis: from bench to bedside

Recent therapeutic advances have the potential to improve outcomes of mucormycosis. Lipid formulations of amphotericin B (LFAB) have evolved as the cornerstone of primary therapy for mucormycosis. Posaconazole may be useful as salvage therapy, but it cannot be recommended as primary therapy for mucormycosis on the basis of available data. Preclinical and limited retrospective clinical data suggest that combination LFAB-echinocandin therapy may improve survival during mucormycosis. A definitive trial is needed to confirm these results. Combination therapy with LFAB and the iron chelator, deferasirox, also improved outcomes in animal models of mucormycosis. In contrast, combination polyene-posaconazole therapy was of no benefit in preclinical studies. Adjunctive therapy with recombinant cytokines, hyperbaric oxygen, and/or granulocyte transfusions can be considered for selected patients. Early initiation of therapy is critical to maximizing outcomes; recent developments in polymerase chain reaction technology are advancing early diagnostic strategies. Prospective, randomized clinical trials are needed to define optimal management strategies for mucormycosis.

Analysis of infectious complications in infants with acute lymphoblastic leukemia treated on the Children's Cancer Group Protocol 1953: a report from the Children's Oncology Group

Infants with acute lymphoblastic leukemia have a poor prognosis. The Children's Cancer Group (CCG) 1953 protocol tested the hypothesis that intensification of therapy would improve outcome for these patients. This intensified therapy resulted in better disease control, but resulted in greater toxicity. In this paper, we report the infectious complications associated with this intensified therapy. We retrospectively analyzed the infectious complications reported on the case report forms of all 115 patients enrolled on CCG 1953. Overall 495 infectious complications were identified in 115 patients. Bacterial infections occurred most frequently (74%), followed by viral (13%), fungal (11%), and protozoan (1%). Infection related mortality disproportionately occurred with viral (31%) and fungal (19%) infections. Twenty-three percent (n=26) of patients died of infectious complications, with the majority occurring during induction/intensification. Lower respiratory infections contributed to death in 12 patients and were most commonly viral (n=6) and fungal (n=3). Intensification of therapy resulted in increased infectious complications and deaths compared with previous studies. Future studies will need to focus on: (1) decreasing intensification during the first month of therapy, (2) developing targeted therapies, and (3) improving measures designed to prevent, quickly diagnose, and appropriately treat infections.

[Future role of micafungin in the treatment of invasive mycoses caused by filamentous fungi]

BACKGROUND

Micafungin is a echinocandin. It inhibits beta-1,3-D-glucan synthesis, thus achieving fungicidal activity against virtually all Candida spp., including those resistant to fluconazole, and fungistatic activity against Aspergillus spp., as well as several but not all pathogenic molds. Results from in vitro studies, animal models, small clinical trials, hint at possible future indications such as invasive aspergillosis and empirical viantifungal therapy, although currently there is little information published.

AIMS

To describe published data of micafungin as treatment against invasive mold infections, specially analysing its role in the inmunodepressed host and critical care setting.

METHODS

A systematic review of literature using the principal medical search engines was performed. Terms such as micafungin, aspergillosis, zygomycosis, invasive fungal infections, emerging fungal infections, antifungal treatment or therapy, antifungal prophylaxis, empiric or pre-emptive therapy were crossed. Febrile neutropenia patients were excluded.

RESULTS

Several studies in these setting were identified and were described in this review. Although there were no blinded randomized clinical trials published, treatment or prophylaxis of invasive aspergillosis and other invasive mould infections with micafungin described in open clinical studies were analyzed.

CONCLUSIONS

Micafungin could play a future important role as a primary or rescue therapy, alone or in combination, in the treatment or prophylaxis of invasive fungal infections caused by moulds. New randomized clinical trials are needed to confirm their efficacy.

Pharmacokinetics of an elevated dosage of micafungin in premature neonates

BACKGROUND

Determining the safety and pharmacokinetics of antifungal agents in neonates is important. A previous single-dose pharmacokinetic study of micafungin in neonates demonstrated that doses of 0.75 to 3 mg/kg produced lower plasma micafungin concentrations than in older patients because of increased apparent plasma clearance of micafungin in neonates. The primary objective of this study was to assess the safety and pharmacokinetics of an increased (15 mg/kg/d) dose of micafungin.

METHODS

A repeated dose, open-label pharmacokinetic, and safety trial of intravenous micafungin in 12 preterm neonates >48 hours of life with suspected systemic infections. Neonates received 15 mg/kg/d of micafungin for 5 days. Blood samples were drawn relative to either the fourth or fifth dose. Systemic exposure was assessed by examination of the plasma area under the curve.

RESULTS

The median birth weight and gestational age of the neonates were 775 g and 27 weeks, respectively. No adverse events related to micafungin were detected. The mean area under the curve and clearance for the cohort was 437.5 microg'h/mL and 0.575 mL/min/kg, respectively. The calculated clearance and volume of distribution for neonates was greater than that observed in older children and adults.

CONCLUSIONS

These data suggest that 15 mg/kg dosing in premature neonates corresponds to an exposure of approximately 5 mg/kg in adults. No adverse events related to micafungin were observed.

In vitro activities of echinocandins against Candida krusei determined by three methods: MIC and minimal fungicidal concentration measurements and time-kill studies

We evaluated the in vitro activities of anidulafungin, micafungin, and caspofungin against Candida krusei by determining MIC and minimum fungicidal concentration (MFC) measurements and by the time-kill method. The geometric mean (GM)-MIC/GM-MFC values were 0.1/0.34, 0.25/0.44, and 1/2.29, respectively. The mean times to reach 99.9% growth reduction were 19.1 +/- 18.2 h (mean +/- standard deviation) for 2 mg/liter anidulafungin, 37.4 +/- 8.8 h for 2 mg/liter caspofungin, and 30.7 +/- 12.2 h for 1 mg/liter micafungin. Anidulafungin exhibited the highest time-kill rate, followed by micafungin. The three echinocandins showed fungicidal activity at concentrations reached in serum.

Hepatitis associated with micafungin use in a preterm infant

Micafungin is an echinocandin-class antifungal agent licensed for treatment of invasive disease in adults. The optimal dosing regimens have not been established for infants. We describe a premature infant who developed hepatitis and cholestasis during micafungin therapy initiated for protracted candidemia. Practitioners should be aware of this potential adverse effect if using micafungin in young patients.

Efficacy of micafungin in treating four premature infants with candidiasis

BACKGROUND

Although clinical experience in neonates with candidiasis exists for amphotericin B and fluconazole, these standard treatments are often hindered by drug-associated toxicity or development of resistant strains. The aim of the present study was therefore to investigate the efficacy and tolerability of a new antifungal agent, micafungin (MCFG), for treating Candida infections in premature infants.

METHODS

This was a retrospective cohort study. Premature infants diagnosed with Candida infections from October 2003 to July 2004 were brought to the neonatal intensive care unit at the Center of Perinatal Medicine, Nara Medical University Hospital. Four newborns were given 0.5-1.0 mg/kg per day micafungin.

RESULTS

Four premature infants (mean +/- SD gestational age, 24.1 +/- 0.9 weeks; mean +/- SD birthweight, 579.3 +/- 80.5 g) experienced complications from Candida infection; two cases of the fungal infection were caused by Candida glabrata and two cases were caused by Candida albicans. MCFG was administered at 0.5 or 1.0 mg/kg per day (mean dosage days, 9.8 +/- 3.1 days) and it decreased beta-D-glucan levels while improving clinical symptoms in all cases. Additionally, there were no apparent side-effects.

CONCLUSION

MCFG is both effective and tolerable for use in premature infants suffering from Candida infections.

Clinical practice guidelines for the management of candidiasis: 2009 update by the Infectious Diseases Society of America

Guidelines for the management of patients with invasive candidiasis and mucosal candidiasis were prepared by an Expert Panel of the Infectious Diseases Society of America. These updated guidelines replace the previous guidelines published in the 15 January 2004 issue of Clinical Infectious Diseases and are intended for use by health care providers who care for patients who either have or are at risk of these infections. Since 2004, several new antifungal agents have become available, and several new studies have been published relating to the treatment of candidemia, other forms of invasive candidiasis, and mucosal disease, including oropharyngeal and esophageal candidiasis. There are also recent prospective data on the prevention of invasive candidiasis in high-risk neonates and adults and on the empiric treatment of suspected invasive candidiasis in adults. This new information is incorporated into this revised document.

Therapeutic strategies for invasive fungal infections in neonatal and pediatric patients

Invasive Candida and Aspergillus infections are the most commonly encountered fungal infections. They appear to be life threatening in the setting of profound immunosuppression, whereas cases that are resistant to antifungal therapy are occasionally encountered. Novel antifungal triazole and echinocandin agents appear to exhibit good activity as first-line or salvage therapy, whereas the use of amphotericin B formulations is particularly valuable in neonates. Significant differences in toxicity have been demonstrated among various antifungal agents with in vitro activity from available comparative data on fungal infections in children: however, no clear difference in treatment efficacy has been demonstrated. However, very little data are available about neonates. Host factors and responsible fungal species most frequently guide the choice of therapy.

Micafungin in the treatment of invasive candidiasis and invasive aspergillosis

Micafungin is an echinocandin antifungal agent available for clinical use in Japan, Europe, and the United States. Through inhibition of β-1,3-glucan production, an essential component of the fungal cell wall, micafungin exhibits potent antifungal activity against key pathogenic fungi, including Candida and Aspergillus species, while contributing minimal toxicity to mammalian cells. This activity is maintained against polyene and azole-resistant isolates. Pharmacokinetic and pharmacodynamic studies have demonstrated linear kinetics both in adults and children with concentration-dependent activity observed both in vitro and in vivo. Dosage escalation studies have also demonstrated that doses much higher than those currently recommended may be administered without serious adverse effects. Clinically, micafungin has been shown to be efficacious for the treatment of invasive candidiasis and invasive aspergillosis. Furthermore, the clinical effectiveness of micafungin against these infections occurs without the drug interactions that occur with the azoles and the nephrotoxicity observed with amphotericin B formulations. This review will focus on the pharmacology, clinical microbiology, mechanisms of resistance, safety, and clinical efficacy of micafungin in the treatment of invasive candidiasis and invasive aspergillosis.

Micafungin versus liposomal amphotericin B for pediatric patients with invasive candidiasis: substudy of a randomized double-blind trial

BACKGROUND

Invasive candidiasis is increasingly prevalent in premature infants and seriously ill children, and pediatric data on available antifungal therapies are lacking.

METHODS

We conducted a pediatric substudy as part of a double-blind, randomized, multinational trial to compare micafungin (2 mg/kg) with liposomal amphotericin B (3 mg/kg) as first-line treatment of invasive candidiasis. Treatment success was defined as clinical and mycologic response at the end of therapy. Statistical analyses were descriptive, as the sample size meant that the study was not powered for hypothesis testing.

RESULTS

One hundred six patients were included in the intent-to-treat population; and 98 patients-48 patients in the micafungin group and 50 patients in the liposomal amphotericin B group-in the modified intent-to-treat population. Baseline characteristics were balanced between treatment groups. Overall, 57 patients were <2 years old including 19 patients who were premature at birth; and 41 patients were 2 to <16 years old. Most patients (91/98, 92.9%) had candidemia, and 7/98 (7.1%) patients had other forms of invasive candidiasis. Treatment success was observed for 35/48 (72.9%) patients treated with micafungin and 38/50 (76.0%) patients treated with liposomal amphotericin B. The difference in proportions adjusted for neutropenic status was -2.4% [95% CI: (-20.1 to 15.3)]. Efficacy findings were consistent, independent of the neutropenic status, the age of the patient, and whether the patient was premature at birth. Both treatments were well tolerated, but with a lower incidence of adverse events that led to discontinuation in the micafungin group (2/52, 3.8%) compared with the liposomal amphotericin B group (9/54, 16.7%) (P = 0.05, Fisher exact test).

CONCLUSIONS

Micafungin seems to be similarly effective and as safe as liposomal amphotericin B for the treatment of invasive candidiasis in pediatric patients. (ClinicalTrials.gov number, NCT00106288).

Role of plasma proteins in pharmacokinetics of micafungin, an antifungal antibiotic, in analbuminemic rats

There were no significant differences in the pharmacokinetics of micafungin and expression of hepatic multidrug resistance-associated protein 2 (ABCC2/Mrp2) between analbuminemic and Sprague-Dawley rats. Micafungin bound strongly to high-density lipoprotein (HDL) and moderately to gamma globulin. These results suggest that HDL and gamma globulin contribute to the pharmacokinetics of micafungin.

Micafungin for the prophylaxis and treatment of Candida infections

Invasive fungal infection is a significant cause of morbidity and mortality worldwide. The incidence of these infections is steadily increasing. In addition, strains resistant to many commonly used antifungal agents are becoming more prevalent. Many new antifungals have become commercially available in recent years, which have vastly improved the ability to treat these infections effectively. Micafungin is one of three commercially available echinocandins available for use in the USA. This class of agents possess a unique mechanism of action that helps to reduce toxicity while maintaining potent antifungal activity. Micafungin is currently approved for the treatment of esophageal candidiasis in adults and is the only in its class approved for the prophylaxis of Candida infection in patients who have undergone hematopoietic stem cell transplantation. It was also recently approved in the USA for the treatment of candidemia and other forms of invasive candiaisis (acute disseminated candiaisis, Candida peritonitis and abscess). In general, micafungin is well tolerated and has favorable safety and drug-interaction profiles.

[The role of anidulafungin therapy in solid organ transplant recipients]

Anidulafungin is a new echinocandin recently approved for the treatment of esophageal candidiasis, candidemia and other forms of invasive candidiasis, such as peritonitis and intra-abdominal abscesses in non-neutropenic patients. It is fungicidal against Candida spp. and fungistatic against Aspergillus spp. It is active against Pneumocystis jirovecii. In contrast, anidulafungin does not have activity against Cryptococcus neoformans, Zygomycetes or molds, other than Aspergillus spp. The drug is well tolerated, even in patients with renal or hepatic impairment. In contrast to other echinocandins, it does not significantly interfere with the cytochrome P450 pathway and has a low drug-drug interaction profile, including calcineurinic agents and other drugs used in transplant recipients. So far, anidulafungin appears to have an excellent safety profile with few adverse events and it promises a special consideration in the management of fungal infections happening in transplant recipients.

Advances in antifungal therapy

The prevalence of invasive fungal infections (IFIs) has increased over the past three decades owing to the increasing numbers of immunocompromised hosts. These infections are associated with significant morbidity and mortality. Recent significant advances in antifungal therapy include the broad-spectrum triazoles (voriconazole and posaconazole) and a new class of antifungals, the echinocandins (caspofungin, micafungin, and anidulafungin). New treatment strategies, such as combination therapy and pre-emptive therapy, are being investigated. There have also been significant improvements in diagnostics; the galactomannan enzyme immunoassay and the beta-glucan test are now part of the EORTC/MSG criteria for diagnosis of IFI. Despite these advances, there remain a number of unanswered questions regarding optimal management of serious fungal infections, and research continues to discover and develop new therapies and evaluate new management strategies.