Preemptive Oral Gabapentin 600 mg in Reducing Morphine Requirement After Non Obstetric Lower Abdominal Surgery

Seventy-two subjects were given informed consent before enrolling the study and randomized into two groups; gabapentin and placebo. Two hours before the incision, patients were given preemptive analgesia, either gabapentin or placebo. Non-invasive blood pressure monitor, electrocardiogram (ECG), and pulse oxymetry were set on the subjects in the operating room. General anesthesia induction was done by fentanyl 2 mcg/kg and propofol 2 mg/kg. Endotracheal tube (ETT) intubation was facilitated with atracurium 0.5 mg/kg as muscle relaxant. Maintenance was done by sevoflurane, oxygen, and compressed air. After surgery, patients were extubated until fully conscious. Patients will be transported to recovery room postoperatively. Besides paracetamol as the postoperative analgesia, we also attached patient controlled analgesia (PCA) system to patients' intravenous line using continuous ambulatory delivery device (CADD) contained morphine 1 mg/ml with settings 1 mg per requirement, interval limit within 5 minutes, maximum dose 6 mg/hour intravenously. Cumulative morphine requirement, mean visual analogue scale, and time interval after surgery to the first administration of morphine will be assessed in this study.

Inclusion criteria

• Male or female
• Age: 18-65 years old
• Weigh in range around 20% of the ideal body weight
• Physical status ASA I-II
• Scheduled for elective non-obstetric lower abdominal surgery with general anesthesia
• Duration of surgery less than 4 hours
• Patients who agreed to participate in this study and sign informed consent

Exclusion criteria

• Patients who have history of allergy or hypersensitivity to gabapentin, paracetamol, morphine, or the other opioids
• Patients who consumed analgesia and NSAID less than 12 hours before surgery
• Patients who experienced physical trauma less than 4 days before surgery
• Patients who have contraindications to gabapentin, morphine, and paracetamol
• Patients who were treated with neuraxial block or peripheral nerve block before and during surgery
• Patients who have history of diabetes, severe live or renal disease
• Patients who were treated with antihypertension, sedatives, hypnotics, antidepressants, and the other drugs that have effects on nervous system
• Patients who have psychiatric disorders
• Patients who consumed gabapentin before perioperative period
• Pregnant or breastfeeding patients