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.

Exploring Cholinergic Compounds for Peripheral Neuropathic Pain Management: A Comprehensive Scoping Review of Rodent Model Studies.

Neuropathic pain affects about 7-8% of the population, and its management still poses challenges with unmet needs. Over the past decades, researchers have explored the cholinergic system (muscarinic and nicotinic acetylcholine receptors: mAChR and nAChR) and compounds targeting these receptors as potential analgesics for neuropathic pain management. This scoping review aims to provide an overview of studies on peripheral neuropathic pain (PNP) in rodent models, exploring compounds targeting cholinergic neurotransmission. The inclusion criteria were original articles on PNP in rodent models that explored the use of compounds directly targeting cholinergic neurotransmission and reported results of nociceptive behavioral assays. The literature search was performed in the PubMed and Web of Science databases (1 January 2000-22 April 2023). The selection process yielded 82 publications, encompassing 62 compounds. The most studied compounds were agonists of α4ß2 nAChR and α7 nAChR, and antagonists of α9/α10 nAChR, along with those increasing acetylcholine and targeting mAChRs. Studies mainly reported antinociceptive effects in traumatic PNP models, and to a lesser extent, chemotherapy-induced neuropathy or diabetic models. These preclinical studies underscore the considerable potential of cholinergic compounds in the management of PNP, warranting the initiation of clinical trials.