Methadone to Reduce Chronic Opioid Use After Major Spine Surgery: The MEND Pilot Feasibility Study

The Centers for Disease Control and Prevention reports a nearly 10-fold increase in the number of deaths from all types of drug overdose over the past 20 years, including 82,000 deaths that occurred in 2022 alone. Prescription opioid medications contribute to drug overdose deaths. In fact, nearly 294,000 people in the US died from a drug overdose involving prescription opioid medications between 1999 and 2022 - a 4-fold increase in prescription drug overdose deaths. Surgery is often the first exposure to opioid medications for many patients. Severe pain after surgery requires potent opioid medications which control pain but includes risk of long-term opioid-dependence. Long-term opioid use and abuse may lead to opioid addiction, overdose and even death.

Patients undergoing spine surgery experience severe postoperative back pain immediately after surgery, which requires treatment with potent opioid medications. Severe pain in the first 1 to 3 days after surgery often develops into chronic back pain, which increases risk for long-term use and abuse of prescription opioid drugs. Importantly, compared with all other surgical procedures, back and spine surgery is associated with the highest risk of long-term use and abuse of prescription opioid medications. Certainly, chronic back pain requires opioid use in approximately 50% of patients at three months after surgery, 40% at six months, 30% at one year, and 17% at two years. A financial burden exists as well. Over the past 10 years, annual prescription opioid expenditures for pain after spine-related surgery increased 660% from $246 million in 1997 to $1.9 billion in 2006. Monthly direct and indirect costs associated with the treatment of postoperative persistent and chronic back pain totaled an average US $3,455 per patient. These data indicate that new approaches that provide effective, long-lasting, and safe treatment of postoperative pain after complex spine surgery while reducing risk of persistent and chronic postoperative pain and prolonged opioid use and reducing cost are needed.

Multiple randomized clinical trials in patients undergoing a variety of surgical procedures have demonstrated that intraoperative methadone significantly reduces postoperative analgesic requirements in the immediate postoperative period, compared to shorter-acting opioids. Methadone is a unique long-acting opioid medication that demonstrates rapid onset and prolonged duration of action with a half-life of 24-36 hours and pain relief lasting 8-12 hours. Like other opioids, methadone activates the mu-opioid receptor, but it also has additional effects on the brain, such as blocking NMDA receptors and reducing reuptake of serotonin and norepinephrine. These actions may help improve recovery by reducing pain sensitivity, preventing tolerance to the medication with euphoric effects, preventing opioid-induced hyperalgesia and opioid tolerance. One investigation studied the impact of methadone on persistent and chronic post-surgical pain in a small randomized controlled trial (RCT) with 66 patients. Participants were randomized to receive either a single intraoperative intravenous dose of methadone (0.2 mg/kg) or intravenous hydromorphone (2 mg). Methadone not only reduced the incidence of post-surgical pain in the study group. but also the percentage of patients who required opioid analgesics at three months (10 versus 41%), suggesting a protective effect against prolonged opioid consumption. Pilot data from another investigation using preoperative oral methadone in patients undergoing cardiac surgery showed reduction in postoperative morphine consumption in the first 24 hours. If acute postoperative pain is reduced, the development of chronic pain may also decrease, as well as the need for long-term opioid therapy, dependence, and abuse.

Although methadone provides effective analgesia for major surgery, a thorough safety assessment of perioperative intravenous methadone is needed. A large retrospective study of 1,478 patients after major spine fusion surgery who received IV methadone (0.13 mg/kg) along with other analgesics, including lidocaine, ketamine, and hydromorphone noted respiratory depression in one-third of patients and hypoxia in nearly 80%. Other concerns include a nearly 60% incidence of electrocardiographic QTc prolongation and 1.1% experienced myocardial infarction (MI) postoperatively. However, there is limited data on the impact of a single perioperative dose of methadone on QTc prolongation. Additional potential complications such as respiratory depression requires further investigation.

If proven safe and effective, postoperative pain therapy with methadone could offer a simple, practical strategy to improve long-term outcomes in this high-risk population undergoing spine surgery. This investigation will the safety and efficacy of postoperative methadone treatment in patients undergoing spine surgery and the opioid-sparing effects of methadone at 3 months after surgery.