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What is the influence of methadone on postoperative analgesia after lumbar interbody fusion in opioid naïve patients or patients who are taking less than equivalent of 15 mg IV morphine each day? What is the incidence of opioid related postoperative side effects after the administration of methadone in the operating room?

Hypothesis:

1. We hypothesize that 0.2 mg/kg of methadone will result in decreased postoperative hydromorphone consumption compared to hydromorphone alone in opioid naïve patients or patients who are taking less than the equivalent of 15 mg IV morphine a day undergoing lumbar interbody fusion.
2. We hypothesize that the incidence of opioid related postoperative side effects will not be increased by the administration of methadone in the operating room.

Inclusion Criteria:

• ASA physical status I, II, and III, male and non-pregnant female
• English-speaking patients
• Ages 18-75 years
• Undergoing elective one or two level posterior lumbar interbody fusion

Exclusion Criteria:

• Use of more than the equivalent of 15 mg of IV morphine/24 hr in the past 2 weeks.
• Use of drugs within the past 6 months that effect the pharmacokinetics or pharmacodynamics of opioids (i.e., benzodiazepines, anti-retroviral agents, rifampin, ketoconazole, erythromycin, or phenytoin).
• history of substance abuse at any time in the past
• known QT prolongation
• Non-elective operations (i.e., cancer or trauma)
• severe hepatic impairment (serum albumin < 3.0 g/dL in the presence of a history of liver disease)
• pregnancy
• inability to operate a patient-controlled analgesia device