Update on Echinocandin Antifungals

Echinocandins are semisynthetic lipopeptides that competitively inhibit an essential cell wall component of Candida and aspergillus. They are generally inactive against other fungi. Resistance to these agents is infrequent to date. Echinocandins exhibit low oral bioavailability and are available only as parenteral formulations that are dosed once daily. None of the echinocandins serve as major substrates, inducers, or inhibitors of cytochrome P450 enzymes or the P-glycoprotein transport system; thus they have a low potential for serious drug-drug interactions. In candidemia trials, all echinocandins showed similar rates of success and were as efficacious as fluconazole, amphotericin B, or lipid formulations of amphotericin B. Caspofungin and micafungin have been studied as single-agent therapy in patients with invasive aspergillosis and will likely remain as second-line agents. However, because of their unique mechanism of action, echinocandins are ideally suited for use in combination with polyenes or azoles and are likely to be used increasingly in immunosuppressed hosts despite a current lack of controlled trials demonstrating efficacy. Limited experience suggests that caspofungin and micafungin are safe to use in pediatric patients. Hospital formulary committees are likely to view the three echinocandins as equivalent agents and place the least expensive agent on formulary.