How do echinocandins differ in pharmacokinetics from other antifungal agents?

Echinocandins are a class of antifungal agents that are distinctive in their pharmacokinetic profile, particularly in their mode of administration. Unlike many other antifungal agents that can be taken orally, echinocandins are primarily administered intravenously. This intravenous route ensures that the drug is rapidly available in the bloodstream and can achieve effective concentrations against fungal infections, especially in severe cases where oral administration might not be feasible.

The intravenous requirement is related to their molecular structure, which does not allow for efficient absorption through the gastrointestinal tract. This characteristic sets echinocandins apart from other antifungal agents that often have oral formulations, such as azoles or polyenes, which can be used for both outpatient and inpatient settings. The method of administration also influences their distribution and the onset of action within the body, which is especially critical in treating systemic fungal infections.

While echinocandins do have a broad spectrum of activity against certain fungi, their primary distinguishing pharmacokinetic feature is that they are not available for oral administration. Thus, the correct choice highlights a key aspect of their clinical use and effectiveness.