The acute pain after spinal surgery is serious. The most pain is during 24 hours after surgery. The multimodal therapy is a method which is applied to treat the postoperative pain.

Morphine is main analgesic to treat postoperative pain. However, some the side-effects can occur to patients and there are associate with dosage. So, some analgesics usually combinate with morphine to postoperative analgesia, include gabapentin, celecoxib, ketamine, ...

Nefopam is a central analgesic. There are effect prevent hyperalgesia. The effect of the combination of gabapentin with nefopam to postoperative analgesia in spinal surgery hasn't been reported yet.

The gabapentin oral with 600 mg combine with continuously intravenous nefopam with 65 µg/kg/hour during 24 hours after spinal surgery whether to increase the effect of postoperative analgesia.

The investigators hypothesized that the gabapentin oral with 600 mg combine with continuously intravenous nefopam with 65 µg/kg/hour during 24 hours after spinal surgery can decrease 40% of the consumption of morphine during 24 hours.

After enrolled, all participants will randomly assigned into the two groups. The intervention group (GAPA-group) will treated preoperative oral 600 mg of gabapentin. After general anesthesia, all participants of both groups will continuously transfused 65 µg/kg/hour of nefopam during 24 hours. After surgery, all cases will treated analgesia with morphine-PCA (2 mg of singe dose, 5 minutes of lockout time, and 6 mg of one hour).

The efficacy of postoperative analgesia will evaluated with the consumption of morphine during 24 hours.

Inclusion Criteria:

• Age from 18 to 70.
• Spinal selective surgery

Exclusion Criteria:

• Allergy one of drugs in study.
• Neurological disorder.