Effect of Preoperative Oral Pregabalin Versus Intraoperative Fentanyl on Postoperative Analgesia

The Effect of Preoperative Oral Pregabalin and Intraoperative Fentanyl on Postoperative Analgesia in Diagnostic Laparoscopic Gynecologic Surgery: a Comparative Study

Pregabalin is a structural analogue of gamma amino butyric acid (GABA). It binds to presynaptic alpha-2-delta subunit of voltage gated calcium channels in the brain and the spinal cord. Thus, it modulates the release of excitatory neurotransmitters, such as glutamate, norepinephrine, substance-P, and calcitonin gene related peptide. Also, it causes inhibitory modulation of overexcited neurons and restores them to a normal state.

Pre-emptive analgesia aims to reduce postoperative opioid consumption especially in ambulatory surgeries. Pregabalin (PGB) is an emerging drug in this field. Different doses of preoperative oral pregabalin (75, 150 and 300 mg) are described in the literature with a dose-response analgesic relationship and reduction of opioid use; however increasing the dose results in increasing the incidence of side effects mainly sedation and dizziness.

Perioperative use of opioids for analgesia may result in side effects; like nausea, vomiting, excessive sedation, respiratory depression, pruritus, and urinary retention.The concomitant use of opioids with pregabalin may result in excess sedation and somnolence, so, the use of opioids with pregabalin should be limited to patients with inadequate alternative options.

Our study aims to compare the postoperative analgesic effect of pre-operative oral pregabalin (Study group), to the intraoperative intravenous fentanyl (Control group) in diagnostic laparoscopic gynecologic surgery.

Patienrs will be selected by simple randomization by computer generated system. Pregabalin 150 mg oral capsule and a placebo capsule will be available on the morning of operation.

Also, 2 syringes of 10 ml volumes will be prepared; the first contains normal saline and the second contains the fentanyl dose of 1 µg /kg calculated according to the patient's body weight and diluted to a 10 ml volume.

Patients will then be divided into 2 equal groups of 40 patients each:

Group P: Patients will receive oral pregabalin capsule (150 mg) 90 min before induction of anesthesia, and will receive a bolus injection of 10 ml saline at induction of anesthesia.

Group F: Patients will receive oral placebo capsule identical to the trial drug in size, shape and color, 90 min before induction of anesthesia and will receive a bolus injection of 10 ml of 1µg /kg fentanyl at induction of anesthesia.

Inclusion Criteria:

• ASA physical status I

Exclusion Criteria:

• Patients' refusal
• use of sedatives, hypnotics, anti-psychotic or antidepressant drugs
• history of drug/alcohol abuse
• history of chronic pain
• daily intake of analgesics
• history of epilepsy