Anidulafungin (Eraxis) for Fungal Infections

INTRODUCTION Over the last 25 years, the incidence of fungal infections has increased dramatically. Predominantly a nosocomial complication, invasive fungal infections are growing in the expanding population of at-risk hospitalized patients. The greatest risk lies in the ever-increasing number of immunocompromised patients, including patients with human immunodeficiency virus (HIV) infection and those receiving chemotherapy or other immunosuppressive agents.1 Although Candida species remain the most common causeof fungal infections, the epidemiology of invasive fungal infections has changed. The frequency and relative importance of infections caused by Aspergillus are increasing. The lungs are the most common site of primary invasive disease, followed by the central nervous system (CNS).2 A shift has also been seen in the infections caused by candidal organisms. Candida albicans remains the most common pathogen associated with noninvasive disease, such as esophageal or vaginal candidiasis, but non-albicans species of Candida are increasingly associatedwith invasive candidiasis.3 This is of particular concern because Candida infections are now the fourth leading cause of nosocomial bloodstream infections in the U.S., and non-albicans species are often less susceptible to conventional therapy with azoles or amphotericin B.4,5 In addition to concerns regarding efficacy of existing antifungal agents, problems of tolerability also exist. Amphotericin B is associated with significant nephrotoxicity, whereas the azoles have been associated with hepatotoxicity and drug–drug interactions.3,5 Caspofungin (Cancidas, Merck) was the first of the echinocandin antifungal agents to be licensed; micafungin (Mycamine, Astellas) received Food and Drug Administration (FDA) approval in March 2005. Micafungin is thus the second in the class of echinocandins to be approved, making anidulafungin the third. The Food and Drug Administration (FDA) approved anidulafungin in February 2006 for the treatment of candidemia, esophageal candidiasis, and intra-abdominal abscess and peritonitis caused by candidal infection. Although more data are needed to determine whether anidulafungin offers any clinical advantage over the existing agent in this class, one large in vitro surveillance study of C. albicans bloodstream isolates showed that anidulafungin was eight-fold to 16-fold more effective than caspofungin.6,7