A patient presents to the ED with lower back muscle spasm, and is unable to walk to the bathroom because of pain. After multiple narcotics, NSAIDs, and muscle relaxers, the patient is finally ready to go home, but she then asks about using CBD. “My friend used it for something like this, and she said it helped. Can I use it too?”
A physician should understand the chemical interactions and modes of treatment to appropriately recommend any medication, but the majority of physicians do not know anything about the pharmacology or biology of the chemicals in Cannabis. We are not taught anything about Cannabis in medical school, internship, residency, and fellowship beyond its federal scheduling. So, let's start with the basic words that will help build the vocabulary and tools you need to read the literature and understand when there may or may not be interactions with other medications.
Endocannabinoid System: The body's natural system that responds to phytocannabinoids and endocannabinoids. This includes the receptors CB1 (cannabinoids), CB2, and a host of receptors involved in other physiologic responses. (Front Behav Neurosci. 2012;6:9; http://bit.ly/2PXYBgS.) This system generally tends toward homeostasis.
Phytocannabinoids: The cannabinoids that come from the plant Cannabis sativa L. This began with the identification of THC and CBD, the major cannabinoids. But the minor cannabinoids are being evaluated, including CBDA, THCA, CBG, CBGA, CBN, and CBDV, as more studies are done.
CBD: Cannabidiol, one of the major phytocannabinoids of Cannabis sativa L. This is the nonintoxicating chemical in the plant, and it was recently part of a major study for a new drug, Epidiolex. (See below.)
THC: Tetrahydrocannabinol, another major phytocannabinoid of Cannabis sativa L. This is the intoxicating chemical in the plant. It has a number of other major activities including increasing appetite, pain management, and treating nausea and vomiting related to chemotherapy.
Hemp: The Cannabis sativa L. plant that is grown primarily for its stalk and fiber. The plant has to have less than 0.3 percent of THC to classify as hemp.
Endocannabinoids: The naturally-occurring molecules in our multiple organ systems that parallel the plant's phytocannabinoids. The most well-known are anandamide and 2AG.
Terpenes: The essential oils of the plant, which can also be chemically activating or sedating. This is what differentiates many of the plant types from one another, in addition to the major and minor cannabinoids in the plant. Think of lavender, lemon, basil, etc., as the “additional” elements that are terpenes.
Synthetic Cannabinoids: Marinol is a synthetic THC product available at the hospital. Spice, K2, and bath salts are synthetic THC drugs, and bath salts cause acute psychosis and some cannibalistic behaviors.
Organ Systems: Multiple organ systems are involved, including the brain, muscle, skin or soft tissue, GI system, cardiovascular system, and immune system, which is why this medication can affect so many diseases and illnesses. Of note, it does not affect the medulla where breathing is regulated, which is why we do not see acute respiratory death as a side effect as we do with narcotics. There have been two pediatric cases (only one published) of acute cardiac pause as a complication of an acute accidental ingestion of a large amount of THC, which resolved without any interventions.
Lethality: There is no known lethal dose, but as we EPs know, it's only a matter of time before someone figures out how to make a good thing go bad. I always remind people that even water has a lethal dose. There has been a reported case of possible acute psychosis that led to a patient jumping out of a building, resulting in death.
Metabolism: Phytocannabinoids are generally broken down through the liver by the cytochrome P450 pathway. Be aware of exacerbating effects if a patient is taking another medication metabolized through the same pathway as phytocannabinoids. CBD is a much greater inhibitor of CYP P450 than THC. Organ transplant patients taking tacrolimus, for example, should not use CBD, but THC is OK because of the weak inhibition of CYP P450. Antiepileptic medications are also frequently metabolized through the CYP P450 pathway, and there has been increased concern about drug-drug interaction with Epidiolex (plant-based CBD) now on the market.
Epidiolex: A plant-based CBD oil now available in all 50 states, DEA-rescheduled and FDA-approved for treating certain severe seizure disorders. This is not the typical CBD that most people can get, but is much, much stronger and prescribed at much, much larger doses than is the CBD readily available on the internet or in your local Bed Bath and Beyond, hence the increased incidence of side effects and drug-drug interaction in the literature and in patients. Once again, dose matters.
Marijuana: Mexican slang for the plant Cannabis sativa L. It gained popularity as Mexicans immigrated into the United States in the 1920s and 1930s, and was used to create fear around the plant and the immigrants. This slang term was ultimately used by the DEA to list it as a schedule I drug, but we shouldn't refer to Cannabis, its biologic term, as marijuana, just like we don't refer to Ativan as vitamin A in medical papers.
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Dr. Yafaiis an emergency physician, the medical director of the Releaf Institute, an adjunct assistant professor at the John Wayne Cancer Institute, and a vice president of the Society of Cannabis Clinicians. She was a speaker at an educational conference for medical providers on Cannabis on Oct. 5 in Los Angeles along with Kimberly Kirchmeyer, the executive director of the California Medical Board. Find more information atwww.thereleafinstitute.com/conferences.