An Australian retrospective observational cohort comparison of the use of long-acting injectable buprenorphine products.

INTRODUCTION: In early 2019, Australia became the first jurisdiction to have two brands of long-acting injectable buprenorphine (LAI-B) products available. Previously published studies have mostly followed pre-planned dosing schedules and seldom compared use of both products. This study presents a retrospective analysis of the "real-world" dosing requirements of patients on LAI-B. METHOD: Five clinics provided data for patients commenced on LAI-B between 1 February 2019 and 30 June 2021 for buprenorphine doses and intervals between dosing. The study recorded basic demographic data including age, gender, and previous dose of transmucosal buprenorphine. The Local Institutional Ethics Committee provided approval. RESULTS: Over 3600 individual doses (59 % Buvidal® & 41 % Sublocade®) were administered to 340 individual patients (median age 40 years, 63 % male), with the longest duration in treatment of 856 days. Median estimated duration of a treatment episode was 16.5 months (95%CI: 14.3-19.1). Approximately 94 % transferred from transmucosal buprenorphine (median daily dose 16 mg, range 2-32 mg). Most common LAI-B doses were Sublocade® 100 mg (22.4 %) and Buvidal® Monthly 128 mg (21.5 %); Buvidal® Weekly 24 mg (0.8 %) was least used. 13 % transitioned between LAI-B products. Weekly dose intervals were a median 7 days and monthly doses were given a median of 28 days apart. Overall, 36 % discontinued LAI-B before the census date. DISCUSSIONS AND CONCLUSIONS: Most patients who started LAI-B remained in treatment, with similar rates in both products. A small, but appreciable number of people switched brands, suggesting that it remains important to have treatment options available.

Cytochrome P450-2D6 activity in people with codeine use disorder.

Compound-analgesics containing codeine (CACC) have been a common source of codeine for people seeking opioid replacement therapy (ORT) for codeine use disorder (CUD). Our previous work demonstrated no relationship between pre-treatment CACC and ORT buprenorphine doses; we hypothesised that CYP2D6 activity would partially account for this disconnection. One hundred six participants with CUD were compared to a published population sample of 5408 Australian patients. Mean age of participants with CUD at treatment entry was 35 years, with mean 6.1 years duration of CUD. Mean codeine dose was 660 mg/day (range 40-2700 mg). Mean calculated CYP2D6 activity scores were significantly higher in the codeine group (CUD 1.65 + 0.63 vs. Gen pop 1.39 + 0.65, Wilcoxon W = 347,001, p < 0.001). Pre-treatment CACC dose weakly predicted sublingual buprenorphine doses overall; there was a stronger relationship within ultrarapid metabolisers. While normal and ultrarapid metabolisers of codeine were more likely to have a diagnosis of CUD, poor or intermediate CYP2D6 metaboliser status may protect against CUD.

General practitioner attitudes to prescribing hepatitis C antiviral therapy in a community setting.

There is a growing debate about the prescription of hepatitis C virus (HCV) antiviral therapies within a community setting in Australia. This study aimed to identify interest and confidence among general practitioners (GPs) in prescribing HCV antiviral therapy in a community setting. Data from 580 GPs who responded to a cross-sectional population-based survey were analysed to measure: self-reported interest and confidence in initiating HCV antiviral therapy; and/or prescribing maintenance antiviral therapy; and self-perceived education needs about HCV antiviral therapy. Forty-two percent of respondents indicated they would be interested in prescribing HCV antiviral therapy. Most were not confident to initiate therapy (80%). Higher proportions indicated that they would be more confident in prescribing maintenance therapy (35%) rather than initiating (7%) therapy (z=10.5, P<0.001). Confidence in prescribing was related to a higher caseload of patients with HCV (P=0.001) and being a HIV community-based prescriber (P=0.002). Fifty-three percent of respondents expressed an interest in education about HCV antiviral therapy. The initial step to recruit potential primary care prescribers of HCV antiviral therapies should be to develop an integrated education program. Recruitment to this program might be most efficient from GPs with a high caseload of patients with HCV.