This study is a randomized, double blind controlled trial examining the impact of incorporating a single intraoperative intravenous magnesium bolus and infusion into a preexisting Enhanced Recovery After Surgery (ERAS) protocol for colorectal surgery in place of preoperative oral pregabalin. These protocols are pathways designed with the goal of achieving early surgical recovery by utilizing a constellation of perioperative care techniques that include the use of opioid-sparing pain medications, minimally invasive approaches, and prevention of post-operative nausea and vomiting, among others. Intravenous magnesium has shown to be an effective non-opioid analgesic in abdominal surgeries that decreases total opioid consumption, pain, and improves recovery. The purpose of this study is to evaluate whether or not the addition of intravenous magnesium to our institutional ERAS protocol will improve specific outcome measures, and provide additional benefits when compared to oral preoperative pregabalin. The primary outcome is the patient's quality of recovery based on the "Quality of Recovery - 40 Questionnaire" (QOR 40), and secondary outcomes will be opioid consumption, pain, shivering, sedation scores, acute kidney injury, gastrointestinal function, respiratory function, and hospital length of stay.

Inclusion Criteria:

• Elective Laparoscopic Colorectal Surgery
• Age 18-75
• ASA (American Society of Anesthesiologists) Physical Status Classification 1-3

Exclusion Criteria:

• Current use of Buprenorphine/Suboxone or Methadone maintenance treatment
• Known history of substance abuse
• Use of intra- and/or postoperative Ketamine or Lidocaine infusion
• Pre- or postoperative placement of Epidural catheter
• Inability to speak English or communicate verbally
• Chronic Kidney Disease (CKD) Stage 3
• Hepatic Cirrhosis
• Neuromuscular disease
• Heart block on EKG
• Uncontrolled diabetes with Hba1c > 8%
• Known allergies to study drugs