Postoperative nausea and vomiting (PONV) is one of the most undesirable complications after general anesthesia, and may lead to increased hospital stay and health care costs. The risk factors for PONV include sex (female population), nonsmoking status, past history of motion sickness and/or previous PONV, duration of anesthesia and surgical type (particular gynecologic surgery) and postoperative use of opioids. The overall incidence of PONV has been reported to be 30% with considerable variability, but can increase up to 69%- 80% in women undergoing gynecologic surgery with general anesthesia and morphine-patient controlled analgesia (PCA). Serotonin receptor antagonists (5-HT3) have been suggested one of the first line therapies for preventing PONV because of their efficacy and few side effects compared with other antiemetics. However, despite the use of this treatment, the incidence of PONV has been reported to be between 48 % and 50%. Naloxone is a drug used to counter the effects of opioid. It was found that administration of low dose naloxone prevents opioid side effects such as nausea and pruritus without affecting analgesia or opioid requirements in patient receiving morphine PCA. It was reported that the use of two antiemetic acting at different mechanisms is better to prevent PONV than monotherapy.

Therefore, this prospective, randomized, controlled study was designed to investigate the antiemetic efficacy of combination of ramosetron and premixture of naloxone with morphine PCA after gynecologic surgery.

Inclusion Criteria:

• Nonsmoking women (ASA physical status of I or II) scheduled for gynecologic surgery under general anesthesia and postoperative analgesia with a PCA device were included

Exclusion Criteria:

• known hypersensitivity to study medication; the use of antiemetics within 24 hours before surgery; the presence of gastrointestinal, renal, hepatic, or psychiatric disease.