Pharmacological properties of antifungal drugs with a focus on anidulafungin

Drug classes for the treatment of invasive fungal infections include the polyenes, the triazoles and the echinocandins. Older agents such as the commonly used amphotericin B have a number of limitations, including toxicity and requirements for monitoring during treatment. These limitations led to the development of a number of new formulations of the agent, with the aim of reducing toxicity while maintaining or improving efficacy. Regarding other drug classes, some of the newer agents, such as the echinocandins, have more favourable pharmacokinetic/pharmacodynamic (PK/PD) profiles, with less toxicity and no need for monitoring. The newest echinocandin, anidulafungin, offers significant promise for antifungal infections, and has a number of favourable features, including a lack of known drug interactions and no need for dosage adjustment for any degree of renal or hepatic failure. From a pharmacological point of view, knowledge of both PK and PD characteristics of antifungal drugs is mandatory for evaluating the role of the different agents in the clinical setting. Overall, in the search for safer and more efficacious antifungal agents, PK/PD investigations have been valuable for defining optimal antifungal dosing regimens and developing in vitro susceptibility breakpoints. This article reviews the PK/PD properties of the polyenes, the triazoles and the echinocandins, with a focus on anidulafungin.