Morphine and similar substances (called opioids) are often prescribed for moderate to severe pain, such as after a surgery, thus allowing for minimal pain and a better recovery. Unfortunately various, non-dangerous side effects from opioids occur often that limit the way patients feel and can take of themselves, despite otherwise good pain control and minimal limitations from the surgery itself.

In this proposed study the investigators want to examine if the drug aprepitant can decrease the so called "cognitive impairments" opioids may cause, such as drowsiness, loopiness and feeling "high".

This would allow for a better recovery period, in which patients can be more "themselves", participate in activities around them and move forward.

Subjects scheduled for elective surgeries with expected opioid medication for moderate to severe pain and good functional status shortly after surgery will be randomized to receive either aprepitant or placebo shortly before their surgery and for two more days thereafter.

A telephone interview for cognitive status and several specific questions will be used to assess the effect of aprepitant on the subjects' cognitive and functional status.

Inclusion Criteria:

• healthy English speaking, opioid-naive consenting adults

Exclusion Criteria:

• current or very recent (< 3 months) opioid therapy
• morbid obesity
• liver disease
• therapy with pimozide, terfenadine, astemizole, cisapride, vitamin K antagonists (warfarin), hormonal contraceptives
• acute or chronic infections
• immunocompromised status
• hemodynamically unstable, hemorrhage (bleeding)
• recent surgery
• pregnancy, nursing
• younger than 18 years old
• not proficient of the English language