Of the 66 patients who underwent laparoscopic cholecystectomy during the designated time period, only 7 (11%) could be enrolled for the study. The reasons for exclusion from the study are presented in Table 2 and included medical, psychosocial, and technical factors. Standard exclusionary criteria were employed, including potentially pregnant women, children and elderly patients, patients who could not understand informed consent (ie, non-English speakers), and patients who might not consider recruitment voluntary (ie, prisoners). Patients with medical comorbidities, such as ischemic heart disease and abnormal liver function, were also excluded from participation in the study. Other patients were excluded based on weight, prior or ongoing narcotic use, active malignancy, contraindication to a laparoscopic procedure, or failure to consent. Last, patients were excluded based on potential adverse reactions to the study drugs. In a few patients, refusal to participate in the study was based on fear of the complications listed as potential adverse reactions on the informed consent, such as death or liver failure from acetaminophen, a component of a commonly prescribed, marketed combination narcotic given to many ambulatory surgery patients in the United States and to patients in both arms of this study.