In our study, it was aimed to show the contribution of intraoperative intravenous magnesium sulfate administration to peroperative opioid consumption and postoperative analgesia.

Postsurgical pain is one of the most important issues that could impress on postoperative peace and comfort. Laparoscopic hysterectomy associated with intense inflammatory response, resulting in moderate to severe postoperative pain perception The major goal in postoperative pain management is to minimize the dose of medications and lessen side effects, while still providing adequate analgesia. Postoperative pain relief leads to earlier mobilization, shortened hospital staying, reduced hospital costs, and increased patient satisfaction Narcotics are the most common analgesics which are used after the surgeries. But anesthetists are always looking for replaceable methods with fewer side effects and cost . It seems adjuvant analgesics are those desirable replacements. Nowadays there have been many debates on the role of adjuvant analgesics on postoperative pain relief. One way to use adjuvant analgesics is preventive method Preventive analgesia is a method initiated before anesthetic procedure in order to reduce the physiological consequences of nociceptive stimulation and medical adverse effects and has been defined as an antinociceptive treatment that prevents establishment of altered central processing of afferent input from injuries. One of the intravenous adjuvant that has been shown potential in preventive analgesia is magnesium sulfate that could be administered with multiple routes or methods Mg has been used for many years in anesthesia and cardiology as an anticonvulsant or antiarrhythmic drug. The mechanism of the analgesic effect of Mg is not clear but interference with calcium channels and N-methyl-D-aspartate (NMDA) receptor seem to play an important role. It seems that analgesic mechanism of NMDA-antagonists is made by preventing nociceptive central sensitization. Another suggesting mechanism is the role of it on reduction of catecholamine release with sympathetic stimulation, thereby decreasing peripheral nociception or the stress response to the surgery. Data illustrate that the NMDA receptor antagonists "like Mg sulfate" have an effect on pain threshold and could prevent pain perception even with low doses (preventive doses) In our study, investigators aimed to determine the contribution of magnesium sulfate to postoperative analgesia in abdominal hysterectomy by considering its mechanism of action.

The patients were divided into two groups as magnesium sulfate administered and non-administered The magnesium group received a bolus of 20 mg/kg of magnesium sulfate in 100 mL of saline for 15 minutes before induction, followed by a continuous infusion of 20 mg/kg/hr until the skin was closed. The same volume of isotonic saline for the control group was administered as indicated in the magnesium group.

Inclusion Criteria:

• Patient undergoing abdominal hysterectomy
• Between the ages of 20-70,
• ASA I- II

Exclusion Criteria:

• Presence of hepatic and renal dysfunction,
• Presence of cardiac arrhythmia or other cardiac comorbidity,
• Neurological and psychiatric disorder,
• Chronic use of calcium and beta blockers,
• Drug or alcohol abuse,
• Pregnancy and lactation status,
• Patients with a history of allergy to any drug included in the study protocol