Filtering pharmaceutical opioids for injection: What methods are being used and how effective are they?

  • Raimondo Bruno, School of Psychology, University of Tasmania, Australia
  • Mr Nathan Murray, School of Pharmacy, University of Tasmania, Australia
  • Professor Stuart McLean, School of Pharmacy, University of Tasmania, Australia
  • Ms Barbara de Graaff, School of Psychology, University of Tasmania, Australia
  • Ms Sue Brandon, School of Pharmacy, University of Tasmania, Australia

    • Objective
    Injection of pharmaceuticals is increasing in prevalence internationally. In addition to the active drug, tablets include excipient compounds to provide form and assist in delivery mechanisms. Many excipients, for example talc present in MS Contin®, are insoluble and may cause emboli and tissue granuloma when injected, damaging venous and organ systems. This study aimed to determine the approaches to filtering being taken by people that inject pharmaceuticals, and to evaluate their effectiveness.

    Methods
    All consumers attending an inner-city needle distribution outlet during a target fortnight were asked whether and how they had filtered morphine last time they injected the drug, with these questions replicated in the 2007 and 2008 Tasmanian Illicit Drug Reporting System. Interviews were conducted with pharmaceutical drug injectors to provide details of preparation and filtration methods for laboratory replication. Following filtration, number and size of contaminating particles was assessed using light microscopy.

    Results
    While a substantial proportion of consumers interviewed did not filter morphine tablets, among those that did, common methods were cigarette filters (both roll-your-own and tailor-mades), commercial 0.45μm and 0.22μm wheel filters, and less commonly, cotton-buds and alcohol swabs. Laboratory analysis indicated that a 100mg MS Contin® tablet prepared following methods used by injectors contained more than 2 million particles large enough to cause harm in the venous system (≥5μm) prior to filtering. Commercial filters removed 80-90% of particles dependant on whether morphine was prepared using cold or hot methods. The efficacy of improvised filters decreased in the order: 0.22μm=0.45μm>cigarette filters>cotton tips>>alcohol swabs.

    Conclusions
    No method of filtering MS Contin® tablets, even those appearing clear to visual inspection, reduces particle contamination to a level safe for intravenous administration. However, commercial wheel filters and, to a lesser extent, roll-your-own cigarette filters substantially reduce particulate contamination and merit recommendation as part of harm reduction interventions.