The misuse, abuse and diversion of opioid replacement therapies among street abusers

Abstract

Aims: Buprenorphine is a partial opiate agonist believed to offer significant treatment advantages over existing opioid replacement therapies (ORT), such as methadone. Community-based abuse liability studies are needed to complement clinical and laboratory data First, we estimate the overall prevalence of misuse (self-treatment) and abuse (euphoria), as well as diversion. We also examine the psychosocial characteristics and differences between methadone and buprenorphine. Methods: Targeted sampling was used to recruit recent (n = 706) persons who inject drugs (PWID), including those receiving some form of outpatient drug treatment (45%) in San Francisco, CA. Final sample matched previous studies in SF, including demographic (53% white, 79% male, 36% ages 30–44, 63% homeless) and behavioral (13% HIV+) characteristics. Results: Approximately 75% were candidates for ORT, based on heroin and/or prescription opioid (540/706) use. Over 30% of opioid addicts reported nonmedical (either euphoria or self-treatment) use of methadone, compared to 9% for buprenorphine. The prevalence of abuse was higher for methadone (75%) than buprenorphine (10%). Conversely, the prevalence for misuse (1 − % of abuse) was higher among buprenorphine (90%) than methadone (25%). More outpatient clients reported being treated with methadone (50%) than buprenorphine (10%). Among those receiving outpatient treatment and prescribed methadone, approximately 50% abused their own medication compared to virtually none (<1%) of those being treated with buprenorphine. The significant predictors of nonmedical use that differentiated between misuse versus abuse were being out-of-drug-treatment (AOR = 2.6, 95% CI = 1.2–5.7), co-occurring depression (AOR = 1.4, 95% CI = 1.2–2.5), PTSD (AOR = 1.6, 95% CI = 1.1–2.1), and high withdrawal severity history (AOR = 1.1, 95% CI = 1.01–1.3). There were few differences in the risk factor profiles between buprenorphine and methadone. Conclusions: There appears to be differences in abuse liability among street-level abusers, as well as a high rate of self-treatment using ORT. Financial support: R01DA030427 (Novak, PI).