Emma Hitt, PhD

April 23, 2012

April 23, 2012 (Atlanta, GA) — Methadone and buprenorphine are viable analgesic treatment options for patients with chronic pain and comorbid opioid addiction. However, when it comes to safety, buprenorphine has the advantage, new research shows.

Anne Neumann, PhD, from the Addiction Medicine Program in the Department of Family Medicine at the State University of New York at Buffalo, and colleagues presented the findings here at the American Society of Addiction Medicine (ASAM) 43rd Annual Medical-Scientific Conference.

Buprenorphine is a semisynthetic opioid that is used at varying doses either to treat opioid addiction or to control acute or chronic pain. However, according to Dr. Neumann, more evidence is needed regarding its efficacy relative to methadone in chronic pain patients who receive prescription opioids for chronic pain and who subsequently develop opioid addiction.

The randomized clinical trial sought to compare buprenorphine treatment with methadone treatment in chronic pain patients with opioid addiction. The treatment period was 6 months.

Superior Safety Profile

A total of 54 patients were randomly assigned to receive either buprenorphine or methadone. Patients were required to have opioid addiction, as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), as well as chronic pain disorder/syndrome. They were also required to have had a previous unsuccessful attempt at abstinence-oriented treatment.

The buprenorphine/naloxone group received 4 to 16 mg/day, with a daily average of 14.93 mg buprenorphine/3.73 mg naloxone. The methadone group received 10 to 60 mg/day of methadone, with a daily average of 29.09 mg/day.

A total of 13 patients in each treatment group (a total of 26 patients) completed the 6-month treatment and were analyzed.

Both buprenorphine and methadone treatment resulted in a 12.75% reduction of pain after 6 months of treatment compared with the level of pain present at the initial visit, and buprenorphine and methadone treatment were comparable in the amount of analgesia and functioning, the researchers found.

Methadone treatment resulted in less opioid use than buprenorphine treatment (0 vs 5 patients, respectively). However, buprenorphine treatment had a superior safety profile compared with methadone treatment, owing to its reduced likelihood of overdose death and respiratory depression.

Alternative to Opioids

"Buprenorphine and low doses of methadone are treatment options that primary care physicians can use to treat chronic pain and addiction to short-acting opioids," Dr. Neumann told Medscape Medical News.

However, she pointed out that the average dose of methadone was very low (29 mg/day). "The dose range we chose for the study was 10 to 60 mg, and I expected many patients to take the highest dose of methadone: 60 mg," she said.

According to Dr. Neumann, in the clinical setting, much higher doses of methadone are prescribed.

"Despite these low doses of methadone, patients with chronic pain and opioid addiction reported significant analgesia and no additional opioid use at 6 months," she said.

She added that many patients in the study reported an improvement of functioning during these 6 months. However, she noted, "our data did not show any changes in functioning, presumably because our measure for functioning (0 - 10 point scale) was not sensitive enough. Therefore, it remains unclear whether these medications can indeed improve function, and we are currently conducting a follow-up study to address this question."

"Furthermore, the neuropsychological mechanisms of action of these medications need to be explored, as do the long-term effects (after 3 to 5 years of treatment)," she said.

Need for Ongoing Monitoring

Commenting on the findings for Medscape Medical News, Herbert L. Malinoff, MD, said the study suggests that methadone and buprenorphine appear to have equal efficacy in the treatment of chronic pain in opioid addicted patients, but buprenorphine has advantages in terms of safety.

"Clinicians may choose to use buprenorphine in an office-based setting to treat pain in their opioid-addicted patients rather than referring them to federally licensed methadone clinics," he said.

Dr. Malinoff, who is in the Department of Anesthesiology at the University of Michigan Health System in Ann Arbor, adds that it is important for clinicians to remember that treating pain in the opioid-addicted patient requires ongoing monitoring for recovery status, nonprescribed drug use, and toxicity.

American Society of Addiction Medicine (ASAM) 43rd Annual Medical-Scientific Conference. Abstract P7, presented April 20, 2012.

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