Aprecap I.V. blocks the actions of chemicals in the body that trigger nausea and vomiting. Aprepitant is used in adults and children to prevent nausea and vomiting caused by cancer chemotherapy. Aprepitant is also used (only in adults) to prevent nausea and vomiting that may be caused by surgery. Aprepitant is given ahead of time and will not treat nausea or vomiting that you already have. Aprepitant capsules are for use in adults and children who are at least 12 years old. Aprepitant oral suspension (liquid) can be given to adults and children as young as 6 months old.