Aprepitant is used as:

The actions of substance P and neurokinins A and B are mediated by three G protein-coupled tachykinin receptors designated NK 1, NK 2, and NK 3. Several nonpeptide NK1 receptor antagonists have been developed. These compounds are highly selective and orally active, and enter the brain. Recent clinical trials have shown that these antagonists may be useful in treating depression and other disorders and in preventing chemotherapy-induced emesis. The first of these to be approved for the prevention of chemotherapy-induced nausea and vomiting is aprepitant. Ref: Katzung, 11th edition, Chapter 17.