Untreated, one third of patients undergoing general anesthesia will have postoperative nausea, vomiting, or both.

Patients often rate postoperative nausea and vomiting (PONV) as worse than postoperative pain. PONV increases the risk of aspiration and has been associated with suture dehiscence, esophageal rupture, subcutaneous emphysema, and bilateral pneumothoraxes. PONV frequently delays discharge, and is the leading cause of unexpected hospital admission after planned ambulatory surgery.

Nabilone (Cesamet®) is a synthetic cannabinoid developed in the 1970s which is a potent CB1 agonist. The use of nabilone in preventing nausea and vomiting in patients receiving chemotherapy has been thoroughly investigated. Results from clinical studies demonstrated the efficacy, safety, and tolerability of Cesamet in this population. There has been success in the past translating treatments for chemotherapy-induced nausea and vomiting (ie. 5-HT receptor agonists including Ondansetron and Granisetron) to use in the perioperative environment.

Only one RCT has studied the use of nabilone for the reduction of PONV. Published in 1995, this study compared the administration of either Cesamet 2 mg or metoclopramide 10 mg given 90 minutes before the operation in patients scheduled for elective hysterectomy in 60 women. This study failed to show any significant difference between groups. There are several limitations to this study including a poorly optimized dosing regimen, a small sample size, and a comparison group lacking clinical generalizability.

This study will investigate the use Cesamet vs Placebo, in addition to the regular antiemetic treatment which patients receive at the discretion of the managing anesthesiologist, for the prevention of PONV. The study group will include patients undergoing general anesthesia for elective ambulatory surgery with at least 3 risk factors (>60% risk) for the development of PONV.

See above

Inclusion Criteria:

• Age 18 or older with an American Society of Anesthesiologists (ASA) physical status of I to III who are scheduled to undergo elective surgery under general anesthesia with pre-anesthesia consultation prior to surgery.
• Subjects must be able to swallow study medication;
• At a risk of postoperative nausea and vomiting of at least 61% percent, according to a simplified risk score, based on the presence of at least three of the following risk factors: female sex, nonsmoker status, anticipated use of postoperative opioid and previous PONV or motion sickness.

Exclusion Criteria:

• Subjects with clinically significant or unstable cardiac, respiratory, hepatic, renal, or other major organ system disease
• Patients who will not be admitted to the PACU post-operatively (patients who are immediately transferred to the ICU)
• Known sensitivity to marijuana or other cannabinoid agents
• Psychotic illness or depression
• Addiction to illicit substances or alcohol
• Non-psychotic emotional disorders.
• Pregnant or lactating
• Subjects who suffer from chronic nausea and/or vomiting;
• Has had treatment with any other investigational drug within 12 weeks prior to randomization
• Subjects who, in the opinion of the investigator, would experience an unacceptable risk from administration of study drug