Prevalence of diversion and injection of methadone and buprenorphine among clients receiving opioid treatment at community pharmacies in New South Wales, Australia

Abstract

Background

This study aimed to investigate the prevalence of diversion and injection of methadone and buprenorphine among clients receiving opioid pharmacotherapy treatment at community pharmacies in New South Wales (NSW), Australia.

Methods

A multi-site cross-sectional survey design was utilised using a self-complete questionnaire. Participants were 508 clients receiving supervised methadone (n = 442) and buprenorphine (n = 66) at 50 community pharmacies. Participants were surveyed about whether they had diverted their currently prescribed pharmacotherapy, whether they had injected methadone or buprenorphine, the frequency, desirability and duration of action of injecting, and the ease of availability of street-purchased pharmacotherapies.

Results

The prevalence of recent diversion was more than 10 times higher among those receiving buprenorphine compared to methadone, with 23.8% of buprenorphine-maintained participants reporting diverting their dose in the preceding 12 months. Seventeen percent of methadone clients had injected methadone in the preceding 12 months compared with 9.1% of buprenorphine clients over the same time period.

Conclusion

The higher prevalence of buprenorphine diversion compared to methadone diversion is likely to be due to its sublingual tablet formulation and difficulty associated with supervising its consumption compared to that of an oral liquid. Methadone diversion is also less prevalent likely due to the high levels of methadone takeaway provision, which also helps to explain the higher levels of recent methadone injecting compared to buprenorphine injecting. A clearer understanding of the motivations for diversion and injection of opioid pharmacotherapies, and the relationship between them is required.

Introduction

The diversion and injection of methadone and buprenorphine is a problem for individuals, communities and treatment providers, and has been widely reported in Australia (Darke, Ross, & Hall, 1996; Humeniuk, Ali, McGregor, & Darke, 2003; Jenkinson, Clark, Fry, & Dobbin, 2005) and internationally (Best et al., 1998; Cicero, Inciardi, & Munoz, 2005; Fountain, Strang, Gossop, Farrel, & Griffiths, 2000; Guichard et al., 2003; Lauzon et al., 1994; Robinson, Kemp, Lee, & Cranston, 2000; Vidal-Trecan, Varescon, Nabet, & Boissonnas, 2003). Diversion is usually defined as diversion of medication to the illicit market, but importantly also includes diversion of supervised medication for personal use outside the supervised treatment site and may be for the purposes of injecting (Cole, 2001; Fountain et al., 2000; Ritter & Di Natale, 2005). The injection of buprenorphine and methadone is associated with adverse outcomes including high levels of local injecting site complications (Darke et al., 1996; Darke, Topp, & Ross, 2002; Jenkinson et al., 2005) and fatal overdose (Caplehorn & Drummer, 2002; Kintz, 2001, Kintz, 2002; Perret, Deglon, Kreek, Ho, & La Harpe, 2000; Pirnay et al., 2004; Schifano et al., 2005; Shah, Lathrop, & Landen, 2005; Zador & Sunjic, 2000), particularly in the case of methadone.

Despite several apparent advantages of buprenorphine over methadone, including safety in overdose and the possibility of less than daily dosing (Eissenberg et al., 1997; Walsh, Preston, Bigelow, & Stitzer, 1995; Walsh, Preston, Stitzer, Cone, & Bigelow, 1994), buprenorphine may be more susceptible to diversion from supervised dosing sites than oral liquid methadone due to its sublingual tablet formulation (McCormick, 2006).

In New South Wales (NSW), Australia, there are more than 16,000 clients receiving methadone (84%) and buprenorphine (16%) for the management of opioid dependence. In NSW, methadone and buprenorphine treatment is delivered in a supervised setting such as a public clinic (providing treatment to 25% of those in treatment), community pharmacies (43% of those in treatment) and private clinics (19% of those in treatment) (NSW Department of Health, personal communication, 2006). Public clinics provide methadone and buprenorphine free of charge and the majority do not provide takeaway doses. Treatment received at community pharmacies and private clinics incurs a dispensing fee, and takeaway doses of methadone are typically provided. The NSW Opioid Treatment Program Clinical Guidelines for Methadone and Buprenorphine Treatment of Opioid Dependence recommend that a maximum four takeaway methadone doses be provided each week with no more than two consecutive takeaway methadone doses being dispensed at one time with a supervised dose required at least once every 3 days (NSW Department of Health, 2006). While the daily supervision of medication, especially in the early stages of treatment, allows both close monitoring of clients and minimises diversion (NSW Department of Health, 2006) the requirement for daily attendance is not acceptable to many clients and has been associated with poorer retention in treatment (Pani, Pirastu, Ricci, & Gessa, 1996; Rhoades, Creson, Elk, Schmitz, & Grabowski, 1998; Treloar, Fraser, & Valentine, 2007).

Although current NSW guidelines support the selection of clients considered appropriately stable to receive takeaway doses (NSW Department of Health, 2006), this is not enforceable and in many cases takeaways are provided to clients who do not comply with the prescribers key expectation that the medication will be taken as directed by the person to whom it was prescribed (Hailstone, Indig, Lawrance, Gill, & Anns, 2004). Given that the majority of “street” methadone in NSW is sourced from diverted takeaway methadone doses (Darke et al., 1996; Sunjic & Howard, 1996) a key response to reducing the diversion of methadone has been through limiting the availability of takeaways and increasing the amount of supervised dispensing. That the availability of methadone takeaways is an important determinant in the availability of street methadone is consistent with findings that Australian states with more restrictive takeaway policies generally report a lower prevalence of methadone injecting (Ritter & Di Natale, 2005). The supervised consumption of methadone when accompanied by simple compliance checks such as having a brief conversation with the client after administration to ensure the dose has been swallowed permits the almost certain ingestion of methadone by the intended recipient (Pharmaceutical Services Branch, 2004). When buprenorphine was introduced in Australia in 2000 it was considered that the supervision of buprenorphine would be as an effective approach to reducing diversion as it had been for methadone. In addition, takeaway doses of buprenorphine were not routinely permitted in NSW until the most recent NSW guidelines were released in November 2006 (NSW Department of Health, 2006, NSW Health Department, 2001).

The current study aimed to explore the prevalence of self-reported diversion of supervised methadone and supervised buprenorphine and the prevalence of self-reported injection of methadone and buprenorphine among a sample of clients receiving opioid pharmacotherapy treatment at community pharmacies in NSW.