The aim of this clinical trial is to assess preemptive oral pregabalin administration in the obese patients undergoing laparoscopic sleeve gastrectomy. The main aims of the study are to evaluate postoperative pain treatment and effect on the intraoperative hemodynamical stability.

The participants will be divided into 2 groups: with or without preemptive pregabalin administration.

Pregabalin is a GABA analogue that has analgesic, anxiolytic and effects. There are studies indicating that this drug can be used as an element of multimodal analgesia to decrease opioid requirements in postoperative period. Such an effect would be particularly beneficial for patients with obesity scheduled for laparoscopic sleeve gastrectomy, most commonly performed bariatric surgery.

The investigators hypothesized that preemptive pregabalin administration may improve quality of postoperative pain score with less incidence of opioid side effects as well as similar or better intraoperative hemodynamical stability.

Inclusion Criteria:

• Sleeve gastrectomy in patients with BMI > 40 or >35 with comorbidities
• Written informed consent

Exclusion Criteria:

• Patient's refusal
• Known allergies to study medication
• Inability to comprehend or participate In pain scoring scale
• Inability to use intravenous patient controlled analgesia
• Changes of operation extent during procedure
• Revisional operations
• End stage organ failure