The intrathecal administration of morphine is gaining popularity. It is easy to do and can reduce the pain after surgery up to 24 hours. However, it causes postoperative nausea and vomiting more than other methods providing postoperative analgesia. Patients suffering from these side effects have to spend a longer period of time recovering in the hospital with high cost of medical treatment.

Objective: to study the efficacy of oral administrating of gabapentin 600 mg before surgery to reduce the postoperative nausea and vomiting in patients receiving intrathecal morphine.

Methods: Eighty patients undergoing orthopedic surgery and receiving intrathecal morphine will be randomized into 2 groups. The first group will receive oral gabapentin 600 mg and the second group will receive a placebo tablet. Both groups will receive a standard prophylactic medication for postoperative nausea and vomiting. The degrees of nausea and vomiting in both groups will be assessed over 24 hours postoperatively.

Inclusion Criteria:

• Patients undergoing general or regional anesthesia receiving spinal morphine
• ASA physical status I-III

Exclusion Criteria:

• Patients with allergy to morphine or gabapentin
• Chronic use of narcotics
• Psychotic
• Bleeding disorder
• Cardiovascular disorder
• Liver or renal failure
• Pregnancy or breast feeding
• Neurologic disorder