Deaths related to fentanyl overdoses seemingly plagued headlines in Canada for much of 2016. It seemed every time you would turn on the TV or radio another alarming statistic about a string of deaths from misuse of this prescription drug. Emergency room visits, in Alberta, related to opioids rose a staggering 84% from 2014 to 2016. While the number of opioid overdose related deaths in 2011 was 6 it has dramatically increased to 257 in 2015. Canada’s Health Minister has even had to declare a “national crisis” with respect to opioid overdoses. The magnitude of this issue has really forced Canadians to look at the conditions that got us here, and how we deal with it going forward. Here is a brief introduction to understanding opioids and addiction.
What is an Opioid?
Opioids are a class of drug that are commonly used for pain management. Throughout our body (in the brain and spinal cord, throughout the digestive tract) we have special types of opioid receptors that are involved in perceiving different types of pain. So opioid drugs attach to these receptors and effectively block the transmission of these signals. There are different types of opioid drugs that target different receptor types, with varying strength and speed.
Fentanyl is a one of the strongest opioid drugs available and is 75-125X more potent than morphine. With rapid pain relief (as fast at 90 seconds after administration), reduced allergenic potential, ability to cross the blood-brain barrier, it can be very effective in managing pain. However, the line between safe use and unsafe use is paper thin. Some key concerns are related to toxicity and dependence of this drug.
1.Toxicity: Fentanyl rapidly absorbs through the skin, often given as a transdermal patch, injected intravenously, dissolved under the tongue, or even in a lollipop. It is rapidly absorbed into tissues and then metabolised in the liver. Since it is quite short acting, it was often, and still is prescribed in multiple small doses, or as a sustained release patch to prolong effects. It can also accumulate in fat cells and over time become toxic. Depending on an individual's fat content, skin temperature, liver function etc. the dose must be carefully calibrated. However, in drug abuse this does not happen, higher doses increase the likelihood of shutting down the respiratory system- chest tightening, decreased breathing, pain, vomiting etc.
2. Dependency and Tolerance: As I mentioned earlier along with pain relief there is an overall sedating effect, including on your mood. Prolonged use of opioids can cause a number of reactions. Dependence refers to the fact that when you stop taking the drug, withdrawal symptoms appear (note: these symptoms are distinct from the “reappearance of pain” that can occur, particularly when the source or stimulus of the pain has not been addressed.) This is a physiologic response and involves an entirely different pathway than addiction. Symptoms include watery eyes, irritability, running nose, sweating, insomnia and anxiety. Fentanyl use has been linked with dependence when used for prolonged periods or at higher doses.
Another response that can be simultaneous or as a result of dependence, is that an individual builds a tolerance. This means an individual may become LESS responsive to the SAME dose of the drug in terms of pain reduction, this is called building a tolerance. It's not exactly clear how this develops but researchers are looking at the role of the notorious NMDA receptor, but how it impacts responsiveness to opioid drugs remains unclear.
Developing an Addiction?
Both of these responses can increase the likelihood of developing an addiction but it is important to note that these have been identified as physiologically distinct pathways from those seen in addiction. Addiction has larger physical, psychological, and social implications. Individuals who develop an addiction display drug-seeking behaviours that can have a significant negative impact on their quality of life. Seeking more or higher doses of the drug to relieve pain is not the same as seeking it to satisfy a dopamine dominated reward pathway often associated with addiction.
As you can see it is a very complex issue that requires increased dialogue in order to develop effective management strategies. We will look into some of the emerging management options, from acute management of an overdose to cognitive behavioural therapies to address addiction in future blog postings.
Alberta Health Services: http://www.health.alberta.ca/health-info/AMH-Naloxone-Take-home.html
Cortazzo, M.H.. Copenhaver, D., Fishman, S.M., Major Opioids and Chronic Opioid Therapy. Book Chapter. Practical Management of Pain, 36, 495-507.e3
NIDA (2016). Misuse of Prescription Drugs. Retrieved December 8, 2016, from https://www.drugabuse.gov/publications/research-reports/misuse-prescription-drugs
Wakeman SE. Medications For Addiction Treatment: Changing Language to Improve Care.J Addict Med. 2016 Nov 24.
Fukuda, K. Chapter 31 Opioid .Analgesics. Miller's Anesthesia. Elsevier. 2015.