NEWS ARTICLE SPOTLIGHT!

New heroin treatment option yielding positive results among patients at Melbourne injecting rooms (ABC).

Recently, there was an article posted on the ABC regarding a trial of long-acting injectable buprenorphine in a clinic in Richmond, Victoria, as part of a push to improve outcomes for medication-assisted treatment of opioid dependence.

The article is written with reference to a 34-year old female (‘Summer’) who has struggled with opioid dependence for the past 6 years. The article focuses on some of the benefits of the injectable buprenorphine treatment, compared to regular oral methadone or buprenorphine treatments that are typically available.

In addition, the article also makes reference to recent study in the US in which long-acting buprenorphine injections were trialed. In the double blind, placebo-controlled trial, published in Lancet, 2019, by Haight et al., a total of 489 participants were randomized into 3 groups (2x treatment and 1 placebo). All groups received an injection every 28 days. Both treatment groups received the long-acting (subcutaneous) injectable buprenorphine, on different volume schedules (6 injections of 300mg vs. 2 injections of 300mg, and 4 subsequent injections of 100mg); whereas the control group received a volume matched ATRIGEL placebo injection. All groups also received individual drug counselling. All participants were asked to provide weekly urine samples (20 samples in total), and complete a self-reported illicit opioid use measure (20 assessments in total). The main study effects under investigation were the percentage of participants abstinent from illicit opioid use (based on negative urine samples and self-reported inabstinence); and overall treatment success (defined by individuals achieving over 80% abstinence across the 20 weeks of treatment).

In the Haight et al. (2019) trial, the rate of abstinence among both treatment groups was significantly higher, around 42% (41.3 and 42.7 respectively) compared with 5% in the control. In terms of treatment success, 29% of participants in group 1 and 28% in group 2 achieved over 80% abstinence, significantly higher compared with 2% of participants in the control. Overall, while preliminary, these results demonstrate that evidence for buprenorphine injections, when combined with effective counselling, is compelling. One of the primary implications of the trial is that subcutaneous injection of buprenorphine appears to have an advantage over transmucosal (under-the-tongue) administration in that it prevents the return of potential same-day craving and withdrawal features that are common with current treatment. Also, given the treatment is administered by a GP or health professional, adherence to treatment protocol is retained, and discontinuation of treatment for illicit use is limited. Finally, the authors also point out that the risks of diversion, misuse and harm to children are also reduced.

Returning to the ABC article for a moment, the results from the trial in Melbourne appear to be following a similar trend. The article suggests that, of the 41 patients using the injecting room in the Richmond clinic, there was a dramatic reduction (~60%) in the number of patients returning to use the room. Anecdotally, some patients who were attending the clinic every 2-3 days stopped visiting altogether after commencing the treatment.

One of the reasons why the new buprenorphine treatment might be preferable compared to methadone, can be found in its action. According to the National Guidelines for Medication-Assisted Treatment of Opioid Dependence (2014):
“Buprenorphine is a partial mu opioid agonist. It binds to the mu opioid receptors in the brain and activates them, but not to the same degree as full agonists. The consequence of this is that there is a ceiling effect, with the effect of buprenorphine reaching a maximum level that is not increased further even with increasing doses of buprenorphine. Like antagonists, partial agonists occupy receptors and prevent further activation by a full agonist.” (p.3)

The implication is that the risk of overdose during induction with subcutaneous buprenorphine injection is lower than for methadone. For example, the risk of overdose during methadone induction is high, and has been associated with toxicity and death. Moreover, inadequate initial dosing of methadone can lead to withdrawal. However, until recently, one of the main criticisms of buprenorphine treatment is that it can also precipitate withdrawal due to a higher affinity and lower intrinsic activity than full agonists. As such, buprenorphine displaces agonists from opioid receptors and, in the short term, may not produce sufficient agonist effects to compensate for the displaced opioid, producing withdrawal as the buprenorphine reaches its peak effects. Results from these trials so far appear to show that the long-acting nature of these buprenorphine injections mitigates this risk.

Regardless, the Lancet trial, and the anecdotal evidence from the Richmond clinic both show early promise in the success of long-acting buprenorphine as part of medication assisted treatment of opioid dependence. One key thing to remember with the Haight et al. paper is that treatment also included drug counselling. In order for interventions (such as these) to be successful, there must be integration with other psychosocial aspects. The ABC article touches on the wider implications of medication-assisted treatment, though not explicitly, by highlighting the positive outcomes of the treatment for ‘Summer’, such as living independently in a nice apartment, and reviving her passion for hand-crafting furniture.

Helping individuals reduce and eventually abstain from problematic substance use represents an important role, not just for primary health clinicians; but also those working in community and corrections setting as well.

For more information about buprenorphine in long-acting injectable formulation, visit the Australian Drug Foundation

For more information about opioids in general, visit the ASSIST Portal under ‘drug information’ tab, where you can find downloadable drug information cards.

The opioid drug information card can be downloaded here

You can read the Haight et al. 2019 paper here

You can read the article via the ABC here