Q: Proper use of Pharmacogenomics can inform better patient care in many potential ways. Pain relief by use of Cannabis instead of opioids shows substantial promise. How do you think pharmacogenomic study could guide intelligent clinical use of Cannabis?
A: Over the past decade, pharmacogenomics (the study of how genes affects a person’s response to drugs) has gained much ground. More than 160 drugs currently have pharmacogenomic labeling by the Food & Drug Administration (FDA) and the list is growing. The excitement that surrounds pharmacogenomics and the applications associated with this technology are endless.
In order to understand the role of cannabis for pain pharmacogenomics, one must understand how pain is treated. In my experience as an oncology pharmacist, I have seen first-hand the unbelievable amounts of opioids a cancer patient may take just to gain some relief. Pain is treated according to the World Health Organization’s (WHO) Pain Relief Ladder where pain is treated in steps based on severity (Figure 1). Steps 2 and 3 of the pain ladder begin to include opioids as part of the treatment course since, when used properly, opioids offer the best chance at reducing pain.
An important consideration that is often forgotten is the use of adjuvant agents to help reduce the amount of opioids used when treating pain in general or to help with different types of pain such as neuropathic pain. In regards to cancer, the first clinical trial to show that an adjuvant therapy can help with chemotherapy-induced peripheral neuropathy was duloxetine, a serotonin-norepinephrine reuptake inhibitor (SNRI), typically indicated for depression.
The role of cannabis in pain management, in my opinion, will most likely be as an adjuvant. I do not see cannabis completely eliminating the need for opioids in patients with moderate-to-severe pain, but I believe cannabis can reduce the amount of opioids a patient may take. The main pharmacogenomic focus for cannabis is related to two primary cannabinoid receptors (CB1-R and CBR-2) that marijuana acts upon. Cannabinoid receptors are of great interest to researchers since our own body produces endocannabinoids that play a role in pain. Research associated with genetic polymorphisms in the cannabinoid receptor CNR1 and CNR2 genes are in preliminary stages; however, these genes hold promise to optimize and individualize therapies that act on the cannabinoid receptor. Other pharmacogenetic markers and their role in patients taking cannabis are also being investigated.
The largest barrier to research related to cannabis is that marijuana is classified as a Schedule I controlled substance by the U.S. Drug Enforcement Administration. Researchers are restricted on how marijuana is studied and is a deterrent to those wanting to perform trials in U.S.-respected organizations, such as the American Cancer Society, that have taken the position in supporting the need for more scientific research associated with cannabis to provide better patient care. If marijuana is rescheduled in the U.S., then its barriers to research will be lifted and more studies involving the pharmacogenomics of cannabis can be performed to improve patient care.
Saeed Alzghari’s contact info is included in the author affiliations at the top of this page.
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