Drug Interaction Profile of Posaconazole

Adverse drug events resulting from drug-drug interactions may lead to emergency department visits, hospitalizations, prolonged length of stays, increased medical care costs, and death. Despite the efforts of research, clinical studies, and active reporting to identify and explain these drug interaction pathways, clinicians are often unaware of such drug-drug interactions. Therefore, it is imperative for pharmacists to identify these potential drug-drug interactions and notify the clinicians as well as the patients so that appropriate safety measures and monitoring methods are implemented. Specifically, immunocompromised patients often receive multiple drug regimens which are associated with toxicities and are highly susceptible to drug-drug interactions. Because of the increased use of azole antifungals in the prophylaxis or treatment of invasive fungal infections among these patients, a close monitoring of drug-drug interactions is warranted. Posaconazole (PCZ), an extended spectrum azole antifungal, has been indicated for use in the prophylaxis of invasive fungal infections in immunocompromised patients. The intent of this article is to increase the awareness of the potential drug-drug interactions with PCZ by reviewing the available drug interaction studies of PCZ and other therapeutic agents, specifically Mylanta, cimetidine, phenytoin, midazolam, cyclosporine, tacrolimus, rifabutin, and glipizide. Excluding Mylanta and glipizide, significant interactions have been observed when PCZ was co-administered with these agents. Therefore, avoidance of PCZ with these and other agents which share the same metabolic pathways is recommended. Otherwise, frequent monitoring of drug levels and for adverse drug events as well as dose adjustments may be warranted.