title: Intravenous Delta-9-Tetrahydrocannabinol to Prevent Postoperative Nausea and Vomiting: A Randomized Controlled Trial.
abstract: BACKGROUND
  Evidence suggests that cannabinoids can prevent chemotherapy-induced nausea and vomiting. The use of tetrahydrocannabinol (THC) has also been suggested for the prevention of postoperative nausea and vomiting (PONV), but evidence is very limited and inconclusive. To evaluate the effectiveness of IV THC in the prevention of PONV, we performed this double-blind, randomized, placebo-controlled trial with patient stratification according to the risk of PONV. Our hypothesis was that THC would reduce the relative risk of PONV by 25% compared with placebo.
  
  
  METHODS
  With IRB approval and written informed consent, 40 patients at high risk for PONV received either 0.125 mg/kg IV THC or placebo at the end of surgery before emergence from anesthesia. The primary outcome parameter was PONV during the first 24 hours after emergence. Secondary outcome parameters included early and late nausea, emetic episodes and PONV, and side effects such as sedation or psychotropic alterations.
  
  
  RESULTS
  The relative risk reduction of overall PONV in the THC group was 12% (95% confidence interval, -37% to 43%), potentially less than the clinically significant 25% relative risk reduction demonstrated by other drugs used for PONV prophylaxis. Calculation of the effect of treatment group on overall PONV by logistic regression adjusted for anesthesia time gave an odds ratio of 0.97 (95% confidence interval, 0.21 to 4.43, P = 0.97). Psychotropic THC side effects were clinically relevant and mainly consisted of sedation and confusion that were not tampered by the effects of anesthesia. The study was discontinued after 40 patients because of the inefficacy of THC against PONV and the finding of clinically unacceptable side effects that would impede the use of THC in the studied setting.
  
  
  CONCLUSIONS
  Because of an unacceptable side effect profile and uncertain antiemetic effects, IV THC administered at the end of surgery before emergence from anesthesia cannot be recommended for the prevention of PONV in high-risk patients.
authors.affiliation: From the *Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, and University of Bern, Switzerland; and †Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Maren
authors.initials: M
authors.lastname: Kleine-Brueggeney
authors.forename: Robert
authors.initials: R
authors.lastname: Greif
authors.forename: Rudolf
authors.initials: R
authors.lastname: Brenneisen
authors.forename: Natalie
authors.initials: N
authors.lastname: Urwyler
authors.forename: Frank
authors.initials: F
authors.lastname: Stueber
authors.forename: Lorenz G
authors.initials: LG
authors.lastname: Theiler
mesh_terms: D061605:Administration, Intravenous; D000328:Adult; D000932:Antiemetics / Q000008:administration & dosage* / Q000009:adverse effects*; D003221:Confusion / Q000139:chemically induced; D004311:Double-Blind Method; D013759:Dronabinol / Q000008:administration & dosage* / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020250:Postoperative Nausea and Vomiting / Q000175:diagnosis / Q000517:prevention & control*; D011446:Prospective Studies
chemical_list: D000932:Antiemetics; D013759:Dronabinol