Rezafungin (Rezzayo™): A Comprehensive Pharmacological and Clinical Monograph

I. Introduction and Drug Classification

Rezafungin is a novel, second-generation echinocandin antifungal agent developed by Cidara Therapeutics.[1] It represents the first new approved treatment for candidemia and invasive candidiasis in over a decade, addressing a critical need for new therapeutic options against serious and often life-threatening fungal infections.[2] As a structural analogue of the first-generation echinocandin anidulafungin, rezafungin was specifically engineered to possess enhanced chemical and metabolic stability, resulting in a significantly improved pharmacokinetic profile.[6]

The central innovation and defining characteristic of rezafungin is its exceptionally long terminal half-life, which exceeds 130 hours.[1] This unique pharmacological property permits a once-weekly intravenous (IV) dosing regimen, a stark contrast to the once-daily administration required for all first-generation echinocandins, such as caspofungin and micafungin.[10] The development of rezafungin was not merely an incremental improvement in antifungal potency but a strategic effort to overcome the significant logistical and clinical challenges associated with daily IV infusions. This is particularly relevant for critically ill or hospitalized patients, for whom daily infusions can necessitate prolonged hospital stays, the use of central venous catheters (e.g., PICC lines), and complex outpatient parenteral antimicrobial therapy (OPAT) arrangements.[14] By shifting the treatment paradigm from a daily to a weekly intervention, rezafungin offers the potential to simplify patient management, enhance continuity of care, and optimize the use of healthcare resources.