Intravenous misuse of slow-release oral morphine capsules: how much morphine is injected?

BACKGROUND: The injection of morphine from morphine sulfate capsules containing sustained-release microbeads (Skenan®) is a practice frequently described by French intravenous opioid users. They seek an injectable form of substitution for heroin. Depending on how the syringe is prepared, the morphine rates may vary. The dosage of the capsule, the temperature of the dissolving water and the type of filter used have been identified as the parameters most likely to influence the final quantity of morphine in solution before intravenous injection. The aim of our study was to determine the amounts of morphine actually injected, according to the different preparation modalities described by people who inject morphine and the harm reduction equipment made available to them. METHODS: Different morphine syringes were prepared by varying the dosage of the capsule (100 or 200 mg), the temperature of the dissolving water before adding morphine, ambient (≈ 22 °C) or heat (≈ 80 °C) and four filtration devices: risk reduction Steribox® cotton, risk reduction filter “Sterifilt®”, “Wheel” filter and cigarette filter. The quantification of the morphine in the syringe body was carried out by liquid phase chromatography coupled with a mass spectrometry detector. RESULTS: The best extraction yields were obtained with heated water, independently of dosages (p < 0.01). Yields of 100 mg capsules varied according to the filter (p < 0.01) and the water temperature (p < 0.01), with maximum yields obtained for solutions dissolved in heated water, then filtered with the “Wheel” filter (83 mg). The yields of the 200 mg capsules varied according to the temperature of the water (p < 0.01), without difference according to the filter used (p > 0.01), and maximum yields obtained for solutions dissolved in heated water (95 mg). CONCLUSIONS: No procedure for dissolving Skenan® led to the complete dissolution of the morphine it contains. Whatever the variations in preparation conditions, the extraction rates of the 200 mg morphine capsules were lower than those of 100 mg, without the risk reduction filters adversely impacting morphine extraction. Offering an injectable substitution to persons who inject morphine would make it possible to reduce the risks and damage, particularly overdoses, associated with variations in dosage due to preparation methods. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12954-023-00781-2.