We thank Srivastava and colleagues for their comprehensive review of the available treatments for opioid use disorder in the March issue of Canadian Family Physician, and for emphasizing the importance of accessibility of pharmacotherapy in the primary care setting.1 As they noted, opioid use disorder has a considerable public health effect in terms of morbidity and mortality, and it is essential that eligible patients are offered opioid agonist therapy, given the high risk of relapse and overdose associated with abstinence-based treatment.
Srivastava and colleagues1 propose that methadone should be recommended over buprenorphine-naloxone for injection opioid users, with the rationale that a full opioid agonist might be more effective in relieving withdrawal symptoms and promoting treatment retention than a partial opioid agonist is. In our clinical settings, however, we have had success in treating patients who inject opioids with buprenorphine-naloxone. Individuals who do not respond to optimized doses of buprenorphine-naloxone in the office-based setting are typically offered methadone or referred to a higher level of care depending on their specific needs. Based on our clinical experience and the recent literature, we would like to advocate for the role of buprenorphine-naloxone as another first-line treatment option for injection opioid users.
There are limitations to using the route of opioid use to guide clinical decision making when offering treatment for opioid use disorder. There are few data comparing outcomes of opioid agonist therapy in injection versus noninjection opioid users. Indeed, the systematic review cited by the authors echoes this point.2 Buprenorphine’s high affinity for the μ-opioid receptor, as well as its long “functional” half-life, make its efficacy similar to methadone with regards to treating withdrawal, and both are effective options.3
Several studies have specifically explored the role of buprenorphine as a treatment for injection opioid users.4–7 While some studies have found similar treatment retention rates between buprenorphine and methadone,8–9 others have shown higher attrition in groups treated with buprenorphine.2,10–11 A recent review comparing the effectiveness of methadone and buprenorphine concluded that while low- or flexible-dose buprenorphine is associated with greater treatment dropout, medium or high fixed-dose buprenorphine performs similarly to methadone in terms of retention and suppression of illicit opioid use.12 More important, attrition rates seem to be independent of the route of opioid use. Furthermore, the lack of information regarding participants’ reasons for discontinuing treatment limit our ability to draw conclusions that can inform treatment protocols. Recent clinical guidelines put forth by the British Columbia Ministry of Health recommend buprenorphine-naloxone as a first-line option for opioid use disorder, regardless of route of use.13
Recommending the type of opioid agonist therapy based on the route of drug use when the evidence to support its clinical utility is not clear might have unintended consequences. Social stigma associated with substance use is already a considerable barrier to care for many individuals; further stratifying treatment options by injection versus noninjection use can affect both how forthcoming patients might be in disclosing their use patterns, as well as how comfortable they might feel engaging in methadone treatment.14
As Srivastava and colleagues explain,1 multiple factors should be taken into consideration when helping a patient decide on the appropriate treatment for opioid use disorder. While methadone maintenance programs can provide the structure of observed dosing and have improved treatment retention for a wider range of dosing, the increased risk of overdose, greater medication interactions, and potential for QT-interval prolongation should be considered. While buprenorphine maintenance might have a more favourable safety profile and greater flexibility for patients who are unable to present for daily care, treatment retention can be a challenge. To our knowledge, there are no standardized criteria that guide the decision between both forms of opioid agonist therapy. Ultimately, similar approaches to overdose prevention are needed for patients taking both forms of agonist therapy, as sedation can occur in both cases when medications are combined with other central nervous system depressants. The patient’s comorbid medical and psychiatric conditions, as well as their life circumstances and preferences, must be taken into consideration when discussing treatment options. Providing patients with both options regardless of route of opioid use through a discussion of informed consent will increase timely access to opioid agonist therapy, which can be life-saving.15 Furthermore, an individualized patient-centred approach can improve treatment engagement regardless of the type of opioid agonist therapy offered.16
Footnotes
Competing interests
None declared
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