Postoperative pain is prevalent after intracranial surgery. Patients undergoing craniotomy are typically managed with short acting opioids to enable early and reliable post-operative neurological exam as well as avoid the risk of respiratory depression. However, a plethora of studies have shown that a majority of these patients experience moderate to severe pain in first 48 hours after surgery. Suboptimal pain control can lead to complications such as arterial hypertension and post-operative intracranial hemorrhage, and hence, increased morbidity and mortality.

Intravenous (IV) methadone has a long analgesic half-life and has N-methyl-D-aspartate (NMDA) receptor antagonist and serotonin and norepinephrine reuptake inhibitor (SNRI) properties. It has previously been shown to reduce postoperative opioid requirements, postoperative nausea and vomiting (PONV), and postoperative pain scores in patients that underwent orthopedic, abdominal, complex spine, and cardiac surgery. Similar findings have been shown in obstetric patients that underwent caesarean delivery under general anesthesia as well as patients that underwent gynecologic surgery and received IV methadone intraoperatively.

In a recently published retrospective study, a single intraoperative dose of IV methadone was well tolerated with lower pain scores as well as MME (oral morphine milligram equivalents) requirements for up to 72 hours after elective intracranial surgery.

IV methadone has, however, never been compared with conventional management via IV remifentanil for functional recovery in patients undergoing elective intercranial surgery.

The investigator's hypothesis is that intravenous (IV) methadone is non-inferior to IV remifentanil in patients who undergo elective intracranial surgery. It offers the advantage of being a single dose noninvasive analgesic modality that may contribute to decreasing MME consumption during the first 72 hours postoperatively, controlling postoperative pain, and improving quality of recovery after surgery.

Postoperative pain is prevalent after intracranial surgery. Patients undergoing craniotomy are typically managed with short acting opioids to enable early and reliable post-operative neurological exam as well as avoid the risk of respiratory depression. However, a plethora of studies have shown that a majority of these patients experience moderate to severe pain in first 48 hours after surgery. Suboptimal pain control can lead to complications such as arterial hypertension and post-operative intracranial hemorrhage, and hence, increased morbidity and mortality.

Intravenous (IV) methadone has a long analgesic half-life and has N-methyl-D-aspartate (NMDA) receptor antagonist and serotonin and norepinephrine reuptake inhibitor (SNRI) properties. It has previously been shown to reduce postoperative opioid requirements, postoperative nausea and vomiting (PONV), and postoperative pain scores in patients that underwent orthopedic, abdominal, complex spine, and cardiac surgery. Similar findings have been shown in obstetric patients that underwent caesarean delivery under general anesthesia as well as patients that underwent gynecologic surgery and received IV methadone intraoperatively.

In a recently published retrospective study, a single intraoperative dose of IV methadone was well tolerated with lower pain scores as well as MME (oral morphine milligram equivalents) requirements for up to 72 hours after elective intracranial surgery.

IV methadone has, however, never been compared with conventional management via IV remifentanil for functional recovery in patients undergoing elective intercranial surgery.

The investigator's hypothesis is that intravenous (IV) methadone is non-inferior to IV remifentanil in patients who undergo elective intracranial surgery. It offers the advantage of being a single dose noninvasive analgesic modality that may contribute to decreasing MME consumption during the first 72 hours postoperatively, controlling postoperative pain, and improving quality of recovery after surgery.

Inclusion Criteria:

1. Adult Patients between ages 18 and 65 years old.
2. Undergoing supratentorial intracranial surgery
3. American Society of Anesthesiologists (ASA) physiological status I-III
4. Body Mass Index (BMI) between 18.5 and 45
5. Ability to understand and read English

Exclusion Criteria:

1. Being unable or unwilling to sign a consent
2. Anticipated discharge within 24 hours after surgery
3. Patients requiring Emergent Surgery
4. Preoperative usage of Methadone, or allergy to it.
5. Patients with chronic pain, requiring daily opioid use at the time of surgery, MME >60 as FDA defines opioid tolerant as 60 MME, long-acting forms of opioids such as fentanyl patch, oxycontin
6. Active or Prior Substance Use Disorder, undergoing active treatment with Medication of Opioid Use Disorder including methadone (once daily dosing), Buprenorphine (any formulation) and Naltrexone
7. Preoperative chronic renal insufficiency or failure (defined as a serum creatinine more than 2 mg/dl),
8. Pregnancy
9. Significant liver disease (cirrhosis or hepatic failure)
10. QTc >450 on preoperative electrocardiogram
11. Pulmonary disease necessitating home oxygen therapy
12. Inability to speak or read the English language