Aprepitant With Dexamethasone Versus Ondansetron With Dexamethasone for PONV Prophylaxis in Patients Having Craniotomy

Inclusion Criteria: A patient is eligible for inclusion in this study if all of the following criteria apply: * Age: 18-75 years of age * Surgery: craniotomy under general anesthesia. * American Society of Anesthesiologists (ASA) Status: ASA: I, II, or III * Language: Fluent in the English language * Informed Consent: Written informed consent must be obtained. Exclusion Criteria: A patient will not be eligible for inclusion in this study if any one or more of the following criteria apply within thirty days of patient enrollment in this clinical trial: * Medical: Any condition that may impair a patient's ability to complete any of the study assessments or confound interpretation of results. * Hypersensitivity: Patient has a known immediate or delayed hypersensitivity reaction or known idiosyncrasy to any of the two study medications, ondansetron, or aprepitant. * Other Drugs: Patients should not be taking medications with known antiemetic properties (phenothiazines, butyrophenones, antihistamines), nor should they receive metoclopramide, or other antiemetics preoperatively or 12 hours before the scheduled surgical procedure. * Pregnant or lactating females: A pregnancy test will be performed within 24 hours of entering the study for females of childbearing potential. * Substance Abuse: Clinically significant abuse of substances (alcohol, illicit or prescribed medications) such that the patient is unable to provide informed consent or reliably complete any of the study assessments. * Psychiatric Disease: History of a psychiatric illness that may impair the patient's ability to provide informed consent or complete any of the study assessments. * Nausea verbal rating score (VRS): A VRS nausea score \> 3 (scale 0-10) in the preoperative holding area before pretreatment with the study medications.