John: Hello, I'm John Hilton, editor of the Cochrane Editorial unit. Some patients who take pharmaceutical opioids to treat pain become dependent on these drugs, and might need to switch to medications such as opioid agonists. In May 2016, a new Cochrane Review brought together the relevant evidence on this and we asked Suzanne Nielsen from the National Drug and Alcohol Research Centre in Australia to tell us what they found.

Suzanne: Pharmaceutical opioids are medicines that are commonly used for pain, and they have similar effects in the body to well-known illicit drugs like heroin. In recent years, there have been dramatic increases in pharmaceutical opioid use in many higher income countries and the misuse of pharmaceutical drugs is a major health problem. For example, North America is experiencing an opioid overdose epidemic, with a trebling of opioid-related deaths, driven largely by increases in prescription opioids.
Opioid agonist treatment, also known as opioid maintenance treatment, involves prescribing maintenance doses of an opioid medication in place of the drug of dependence. Opioid agonist treatments, which include medications like methadone and buprenorphine, are one of the main evidence-based treatments for opioid dependence. They are commonly used in the treatment of people with pharmaceutical opioid dependence, which is dependence to opioid medications commonly used for the treatment of pain, although most of the research into their effects has come from studies conducted primarily or exclusively with people who are dependent on heroin.
We wanted to see what research is available on opioid agonists specifically for the treatment of pharmaceutical opioid dependence. We looked for studies of different types of full and partial opioid agonist maintenance treatments (which was defined as at least 30 days), as well as comparisons of opioid agonist maintenance treatment to placebo, detoxification, or other psychological treatments that did not involve an agonist maintenance treatment.
We primarily looked at the effect of these treatments on substance use, as well as how well these medicines kept people in treatment. We had also wanted to look at some other outcomes such as pain, quality of life and employment; but there was insufficient evidence for most of these secondary outcomes.
We found six randomised trials, involving just over 600 people, and assessed that the overall quality of the evidence was low to moderate. Our caution is because of the relatively small size of the studies and the use of open label designs, in which the participants and the researchers knew which medication the person in the study was receiving. Five of the six studies were from the United States. The other was from Iran. Three studies compared different maintenance agonist treatments (methadone and buprenorphine) and three studies compared maintenance buprenorphine with shorter term treatments (detoxification, or brief intervention and referral).
In summary, the two main opioid agonist maintenance treatments, methadone and buprenorphine, appear equally effective for outcomes relating to keeping people in treatment and preventing unsanctioned opioid use. We also found that maintenance treatment is more effective than detoxification or psychological treatment without agonist medication for keeping people in treatment and preventing unsanctioned opioid use.

John: Thanks Suzi. If you would like to explore this evidence in more detail, the full review is available online. Go to Cochrane Library dot com and search ‘opioid agonist treatment’.