Feasibility, safety, and acceptability of intranasal heroin-assisted treatment in Switzerland: protocol for a prospective multicentre observational cohort study.

Background: Heroin-assisted treatment (HAT) is a proven effective treatment option for individuals with severe opioid use disorder (OUD). In Switzerland, pharmaceutical heroin (diacetylmorphine, DAM) is available in tablet form or as injectable liquid. This creates a large barrier for individuals who require the rapid onset of effect but are either unable or do not want to inject, or who primarily snort opioids. Early experimental data has demonstrated that intranasal DAM administration can be a viable alternative to the intravenous or intramuscular route of administration. The purpose of this study is to assess the feasibility, safety, and acceptability of intranasal HAT.

Methods: This study will assess intranasal DAM using a prospective multicentre observational cohort study design in HAT clinics across Switzerland. Patients will be offered to switch from oral or injectable DAM to intranasal DAM. Participants will be followed-up over 3 years, with assessments at baseline, and after 4, 52, 104 and 156 weeks. The primary outcome measure (POM) is retention in treatment. Secondary outcomes (SOM) include prescriptions and routes of administration of other opioid agonists, illicit substance use, risk behaviour, delinquency, health and social functioning, treatment adherence, opioid craving, satisfaction, subjective effects, quality of life, physical health, and mental health.

Conclusions: The results derived from this study will generate the first major body of clinical evidence on the safety, acceptability, and feasibility of intranasal HAT. If proven to be safe, feasible and acceptable, this study would increase the accessibility of intranasal OAT for individuals with OUD globally as a critical improvement in risk reduction.