Buprenorphine-naloxone abuse among participants in the needle exchange programme. A Finnish time-trend study from 2008 to 2018

Background: Since the early 2000's, buprenorphine has been the most used street opioid in Finland. Buprenorphine-naloxone combination drug was originally introduced due to its lower abuse potential when injected compared to monobuprenorphine. Currently, buprenorphine-naloxone combination drug is the most used drug in Finnish opioid agonist treatment. To date, the studies reporting buprenorphine-naloxone abuse and associated factors are scarce. Aim: The purpose of this time-trend study was to examine the prevalence, possible changes and associated factors of buprenorphine-naloxone abuse compared to monobuprenorphine abuse among Finnish i.v.-users. Methods: Participants were people who inject drugs (PWID) attending a needle exchange programme in Turku, Finland. Information on user profile was collected anonymously via questionnaires at four time-points (2008, 2011, 2014, 2018). These questionnaires examined participants substance abuse during the last six months (2008, 2011, 2014), or 30 days (2018) together with socio-demographic factors. Results: Among survey participants, both monobuprenorphine (BUP) and buprenorphine-naloxone (BNX) abuse were common during the 10-year study period: 86%/66% in 2008, 85%/81% in 2011, 75%/80% in 2014, and 80%/72% in 2018. Compared to BUP abusers, lower education level (OR 2.4, 95%CI 1.2-5.0), attending opioid agonist treatment (OR 4.0, 95%CI 1.2-13.5), needle sharing (OR 3.2, 95%CI 1.5-6.8), amphetamine abuse (OR 3.0, 95%CI 1.4-6.6) and methadone abuse (OR 5.6 95%CI 1.6-19.2) associated with BNX abuse. Conclusions: The prevalence of buprenorphine-naloxone abuse among PWID is high in South-Western Finland. Buprenorphine-naloxone abuse seems to relate with more disadvantaged drug use profile compared to monobuprenorphine abuse, and this phenomenon should be addressed in future studies. Harm reduction strategies should be aimed for opioid abusers with buprenorphine-naloxone abuse.