Opioids are one of the oldest and most widely used drug. In many high income countries, their use has increased (Curtis et al. 2019), which has had a corresponding increase in opioid dependence, addiction and overdose (ONS, 2020). In this blog, we describe why we've created this resource, why this research is important, what we've found so far, our methods, and what's to come, enjoy!
Why did we create this catalogue?
The demand for pain relief, coupled with the need to treat opioid dependence and overdose, has incentivized the development of new and potentially less addictive formulations of opioids and alternatives. But the number of opioids is unknown, and there is no central repository that comprehensively catalogues their names, types, and pharmacological effects. So this was the aim for this research, to quantify the number of opioid drugs developed, create a robust list of opioid drug names, and catalogue the opioids based on their pharmacological properties.
Why is this research important?
The increased use and development of opioids may not be reflected in the confidence of prescribers or the knowledge of the public. Studies in primary care have shown that providers often report inadequate training of opioid prescribing for chronic non-cancer pain (Upshur et al. 2006; Roy et al. 2017). Others have found that poor public knowledge of opioids is a barrier in observational research and may drive over- and under-reporting of opioid use and misuse (Palamar et al. 2016; Palamar, 2019).
How a drug is named and classified determines how it is used, and thus misnaming a drug or a lack of knowledge of such names can cause confusion (Kenakin, 2008). A catalogue of opioid drug names and their pharmacology could help bridge the public’s knowledge gap, aid prescribers when choosing an opioid, and centralize information for those developing the next generation of opioids and their alternatives.
What did we find?
We have submitted a manuscript for publication which summarises all of our findings and we will share this when published. In summary, we identified 233 opioid drugs, most (n=133) targeted mu-opioid receptors, almost all (n=191) were agonists at one or more receptors, and most (82%) were synthetic opioids.
What did we do?
We conducted a systematic search of seven sources in November 2020, iincluding the WHO’s ATC index, the British National Formulary, the IUPHAR/BPS Guide to Pharmacology, the INCB Index of Names of Narcotic Drugs, the WHO’s MedNet service for International Nonproprietary Names (INNs), Martindale’s Extra Pharmacopoeia, and the Merck Index, to include opioid drugs that targeted or had an effect or coeffect at one or more opioid receptors. We extracted chemical and nonproprietary names, drug stems, molecular formulas, molecular weights, receptor targets, actions at opioid receptors, and classes based on their origins. Our registered protocol which provides more details on our methods can be found here.
What's next?
Stay tuned! We are developing "The Opioids" section of the website to create useful monographs on common opioids.
As always, if you think you can help improve the Catalogue or have questions/suggestions, please get in touch: georgia.richards@kellogg.ox.ac.uk.