It is common for injecting drug users (IDU) to prepare injections by crushing tablets which are not designed for
parental administration. The injection of insoluble tablet excipients can lead to serious local and systemic medical
complications. The aim of the study was to investigate the effectiveness of various types of filters in removing harmful
insoluble particles from the injections prepared using crushed oxycodone tablets.
Injections were prepared from a sustained-release oxycodone tablet formulation. The filtration of tablet extracts was
carried out following procedures used by IDU using makeshift filter and commercially available filters. Particulate
contamination and oxycodone content were analysed using light microscopy and spectrophotometer.
Unfiltered extracts contained hundreds of thousands of particles of sufficient size to cause harms. Cigarette filters
removed large particles but failed to remove small particles. The combination of cigarette filter and syringe filter (0.45 μm
or 0.22 μm) reduced the particle count by 90 – 95%. A double membrane syringe filter (0.8/0.2 μm) removed more than
99% of the particles. Recovery of oxycodone was more than 95% with the tested syringe filters.
Particulate contamination in injections prepared from crushed tablets can be effectively removed using a combination
process of cigarette filter and syringe filters, or a 0.8/0.2 μm syringe filter. Compared to other filters, the 0.8/0.2 μm
syringe filter did not block, the filtration was quick and easy to perform, and did not retain oxycodone. The use of a
0.8/0.2 μm syringe filter can provide an important harm reduction measure for IDU.