Which of the following antifungal drugs is most likely to be used in a patient with a renal impairment?

Caspofungin is the most suitable antifungal option for patients with renal impairment due to its pharmacokinetic properties. This echinocandin antifungal is primarily metabolized by the liver and does not rely significantly on renal clearance, making it safer for use in individuals with reduced kidney function.

In contrast, other antifungal agents such as Itraconazole, Fluconazole, and Amphotericin B have more pronounced renal implications. Itraconazole is metabolized in the liver but its absorption can be affected by renal function, and it can lead to increased side effects in patients with significant renal impairment. Fluconazole is excreted primarily through the kidneys; therefore, it often requires dose adjustment in those with renal dysfunction to avoid toxicity. Amphotericin B, while not completely renally excreted, can cause nephrotoxicity, especially in patients who already have compromised kidney function, and careful monitoring is necessary during its use.

Thus, due to its safety profile in this context, Caspofungin emerges as the most appropriate choice for a patient with renal impairment.