Abigail Lyndon, a PhD student part funded by DECIPHer at the University of Bristol has recently seen her paper “Risk to Heroin Users of Polydrug Use of Pregabalin and Gabapentin” published in Addiction – a peer-reviewed journal for research in the field of substance misuse and addiction.
Abi has now completed her studies with DECIPHer and was awarded her PhD in July 2017 ahead of starting a medical degree this autumn. Her recently published paper has been highly praised by the journal editor, who offered his “congratulations on an excellent, and rare piece of truly multidisciplinary work with clear and important clinical implications.”
Abi worked under the supervision of Professor Graeme Henderson and Professor Matthew Hickman of the University of Bristol to deliver the project. The study explored the link between pregabalin and gabapentin – two drugs traditionally used to treat conditions such as neuropathic pain and epilepsy – and a rise in the number of overdose deaths in England and Wales.
Throughout her PhD, Abi was mentored by Dr Suzanne Audrey, a senior research fellow from DECIPHer, who oversaw the qualitative side of the data collection. Dr Audrey stated:
“Abi’s work is truly multi-disciplinary. It was gratifying to see that the comments of the participants, all of whom had drug addiction problems, were able to influence the laboratory experiments and may even change policy and save lives.”
The study involved a three-pronged approach of data collection methods, including:
- In-depth interviews with drug users;
- Laboratory respiration studies;
- And statistical analyses of: A) The Office for National Statistics database of drug-related deaths involving gabapentin and pregabalin, B) The Health and Social Care Information Centre (now known as NHS Digital) statistics on the yearly number of pregabalin and gabapentin prescriptions.
This combination of data collection methods enabled the team to draw the following conclusions from the study:
- An increase in the quantity of prescriptions for pregabalin and gabapentin was closely correlated with a higher number of overdose deaths. Prescriptions for these drugs were shown to have increased from 1 million in 2004 to 10.5 million in 2015, with concerns being raised that they have become drugs of misuse.
- The number of deaths from pregabalin and gabapentin has increased and 79% of these deaths also involved opioids such as heroin. Interviews with heroin users demonstrated that these drugs were both easy to access and believed to enhance the effects of heroin.
- Laboratory experiments highlighted that pregabalin enhanced heroin-induced respiratory depression, leading to a greater risk of overdose. This reflected the substantial increase in fatalities involving opioids and pregabalin/gabapentin use in England and Wales.
Several recommendations were made as a result of the study. It was suggested that alternative medications to gabapentin and pregabalin should be offered to opioid dependent patients who are diagnosed with neuropathic pain and other conditions regularly treated with these drugs. Professor Matthew Hickman explained:
“It is important that doctors and people dependent on opioids are aware that the number of overdose deaths involving the combination of opioids with gabapentin or pregabalin has increased substantially and that there is evidence now that their concomitant use – either through co-prescription or diversion of prescriptions – increases the risk of acute overdose deaths.”
It is highlighted in the study that guidance on the management of opioid dependence does not currently emphasize the risks associated with the use of gabapentin and pregabalin, whereas other guidelines (for example in pain management) recommend caution in the use of these drugs due to the risk of misuse. Professor Graeme Henderson concluded that:
“Poly-drug use is very common amongst drug users. We need more multi-disciplinary studies like ours which seek to combine evidence from laboratory experiments on how drugs act, with accounts of what users experience and information on the pattern of drug use and drug harms – in order to make health care workers and drug users aware of the dangers of combining specific drugs.”
Read the full research report published in Addiction here.