The aim of this study is to evaluate the effect of adding different doses of MgSO4 to bupivacaine via OSCTAB block on postoperative pain control for 24 hours in patients scheduled for LC.

Laparoscopic cholecystectomy (LC) is a gold standard for management of gallbladder stones. Early and easily recovery, less operative morbidities, less postoperative pain, improved cosmetics, less hospitalization days and decreased cost are the superiorities of laparoscopic cholecystectomies over open surgical procedures.

Postoperative pain is the major obstacle for early postoperative ambulation and prolongs the hospital stay. Moreover, it has been hypothesized that intense acute pain after LC may predict development of chronic pain (e.g., post laparoscopic cholecystectomy syndrome). So, aggressive perioperative pain prevention is mandatory.

This pain is routinely managed using opiates, which has several side effects. Transversus abdominis plane (TAP) block is a regional anesthetic technique that has gradually become an alternative for postoperative pain control during laparoscopic abdominal surgeries. It involves the infusion of local anesthetic into the fascial plane of the abdominal wall. Oblique subcostal transversus abdominis plane (OSCTAP) block is an US-guided regional anesthesia technique that anesthetizes the nerves of the lower and upper anterior abdominal wall, specifically from T6 to L1.

Rafi et al and McDonnell et al were the first to describe (OSCTAP) block. They described an anatomical landmark technique and provided evidence of blockade to the mid/lower thoracic and upper lumbar spinal nerves as they travelled in the fascial plane between the transversus abdominis (TA) and internal oblique (IO) muscles.

Evidence supporting the presence of (NMDA) receptors in skin and muscles have led to the use of (MgSO4) which is NMDA antagonist via different routes.

Inclusion Criteria:

• • Patients programmed for elective LC.

  • American society of anesthesiologists (ASA) physical state I or II.
  • Age over 18 years and less than 60 years old.
  • Patients of both sex are included in the study.

Exclusion Criteria:

• • Patient refusal.

  • Known hypersensitivity to the study drugs.
  • Body Mass Index > 40 kg/m2.
  • Inability to accurately describe postoperative pain to investigators.
  • Opioid tolerance or dependence.
  • Preexisting history of chronic pain.
  • History of renal, liver, cardiac, neuropsychiatric disorder problems.
  • Bleeding or coagulation abnormality.