Which of the following is a NK-1 receptor antagonist?

Aprepitant is recognized as a NK-1 receptor antagonist, which means it specifically targets and blocks the neurokinin-1 receptor in the brain. This receptor is associated with the pathways responsible for the sensation of nausea and vomiting. By inhibiting this receptor, aprepitant effectively reduces the incidence of both acute and delayed nausea and vomiting, particularly in patients undergoing chemotherapy, making it a crucial medication in the management of these symptoms.

In contrast, ondansetron is a selective serotonin 5-HT3 receptor antagonist, primarily used to prevent nausea and vomiting. Dexamethasone is a corticosteroid that helps manage nausea and vomiting but does not interact with NK-1 receptors. Haloperidol, an antipsychotic, can have anti-nausea properties, but its mechanism does not involve NK-1 receptor antagonism. Therefore, aprepitant stands out as the specific NK-1 receptor antagonist among the listed options.