Clinical and epidemiological features of synthetic cannabinoids and their detection in drug matrices and biological specimens

: (Alternative Format Thesis)

Abstract

Synthetic cannabinoids (SCs) are a large and structurally diverse group of novel psychoactive substances. Typically acting as full agonists at the cannabinoid type 1 and 2 receptors, their use poses significant risks of both acute and long-term harms. Although rates of use in the general population are low, use is common among vulnerable groups, particularly those experiencing homelessness and those in prison. As these populations can be hard-to-reach, there is a lack of up-to-date research in this area. Furthermore, the volume and structural diversity of this class complicates legislative responses as well making their detection in both drug matrices and biological specimens challenging.

The aims of this thesis were to (1) determine the features and patterns of SC use in community and prison settings (2) characterise the profile of SC withdrawal and explore potential treatment interventions within prison settings (3) examine the association between changes to UK drug policy and analytically confirmed indicators of SC harm and (4) evaluate novel and existing methods for detecting SCs in drug preparations and biological specimens.

Firstly, I conducted a primary data collection study in a Category-B prison for adult males in the UK. This research identified key characteristics which were associated with SC use (including greater levels of psychological distress) and highlighted the novel methods of administration being used (vaporising paper-based preparations via modified e-cigarettes). It also showed that treatment interventions should prioritise increasing the time individuals spend in meaningful activity. Next, I characterised the profile of SC withdrawal using data collected as part of this Global Drug Survey. With 284 participants, this represents the largest study of SC withdrawal to date, and it was found that symptoms appear to be similar but more severe compared to cannabis withdrawal.

To address the third aim, I conducted a time series analysis to examine trends in the number of patients presenting to over 34 different hospitals with analytically confirmed SC exposure between 2015 and 2019. This analysis showed that there was not a significant upward or downward trend in presentations after the introduction of the UK 2016 Psychoactive Substances Act.

To address aim 4, I firstly conducted analyses on seven illicit disposable vapes that were submitted by an individual presenting to a drug and alcohol service after experiencing adverse effects. Although purchased as cannabis products, analyses revealed the presence of the SC 5F-MDMB-PINACA at a median concentration of 0.85 mg/ml; and this represents the first ever detection and quantification of SCs in sealed, disposable vapes. Finally, I conducted a pilot study to test the feasibility of collecting samples of oral fluid from people who use SCs in community settings and then detecting SCs in these samples using fluorescence spectroscopy combined with machine learning (ML) techniques. In this study, I collected 47 samples from various homeless hostels and drop-in services. Also, I showed that fluorescent spectral data strongly correlated with participants self-reported exposure to SCs, and ML models trained on those data could predict binary classifications (reported use within 12hours or not) with high accuracy. Although accuracy fell when these models were compared to analytical evidence of SC exposure via liquid chromatography mass spectrometry, these results warrant further investigation.

Taken together, this thesis highlights key features of SC use in both prison and community setting including routes of administration and the products in which they may appear. It has also examined indicators of SC harm experienced at the population level and shown that emergency hospital presentations have not declined despite changes to UK drug policy. Furthermore, this thesis has helped to characterise the features and experiences of chronic harms experienced by people who use SCs and identified treatment preferences among people who use SCs in prison settings. Finally, this thesis demonstrates the feasibility of collecting complex data from hard-to-reach populations who use SCs and provides preliminary support for the feasibility of using a novel analytical approach involving fluorescence spectroscopy to detect SCs in oral fluid. Critically, this may offer promise for improved detection at the point of care.

Date of Award	11 Sept 2024
Original language	English
Awarding Institution	University of Bath
Supervisor	Peter Sunderland (Supervisor), Christopher Pudney (Supervisor) & Tom Freeman (Supervisor)