Medical Marijuana: The Science Behind THC and CBD
Although marijuana remains a Schedule I substance with the Drug Enforcement Agency, medicinal marijuana continues to make headway in today’s medical society and is stirring up controversy among lawmakers, politicians and medical professionals. Since 23 states and the District of Columbia have made medical marijuana legal, it can be fair to say that cannabis is here to stay. The present DEA’s policy (i.e. Schedule I) has made medical research on marijuana almost impossible in the United States. Other Schedule I drugs include LSD and heroin.
Marijuana is the name given to the dried buds and leaves of Cannabis sativa plant varieties, which grow wild in warm dry climates around the globe. Marijuana is commonly known as weed, grass, pot, herb, green, cannabis, hemp, hash, ganja and dozens of other names. Marijuana has been used as medicine for thousands of years but only in the past couple of decades have scientists begun to understand the specific medical benefits of the two main ingredients in marijuana: THC and CBD (link is external).
Over 60 types of cannabinoids have been identified, but two main types have been studied: delta-9-tetrahydrocannabinol, more commonly known as THC, and cannabidiol, which is commonly known as CBD. As it turns out, the human body has its own cannabinoid system known as the endocannabinoid system (link is external), in which the brain and immune system produce cannabinoids, which bind to the body’s receptors known as CB1 and CB2 (link is external).
CB1 receptors are located in the brain and other parts of the central nervous system, as well as in other tissues and organs like the digestive tract, liver, lungs, kidneys and eyes. CB2 receptors are found mainly in tissues related to immune function like white blood cells, bone marrow, tonsils, the thymus and the spleen. Some CB2 receptors have been shown preliminarily to reduce pain on a level equal to the effects of morphine without narcotics and without a high, and that mechanism could open the door to a new non-narcotic pain treatment.
Healing and protective effects
The most well-known ingredient, THC, is responsible for the high that comes from ingesting marijuana, whereas CBD is responsible for many of the healing effects. (link is external) In fact, multiple studies published in the medical literature suggest that CBD is effective in easing the symptoms (link is external) of rheumatoid arthritis, anorexia, multiple sclerosis, movement disorders, chronic pain, nausea, neuropathic pain, chemotherapy side effects and inflammatory bowel disorders.
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CBD also has demonstrated neuroprotective effects, and several academic research centers are exploring its anticancer potential. In fact, a recent study (link is external) explored the action of cannabinoids on treating brain cancer. This study showed that when used in conjunction with radiation therapy, cannabinoids may actually slow the growth of cancer cells in the fastest-killing brain tumors known as gliomas.
A treatment for nausea
In the United States, dronabinol, commonly known by the brand name Marinol, is a Schedule III substance that has been licensed since 1985 for the treatment of nausea and vomiting caused by HIV treatments and since 1992 for appetite loss in HIV/Aids-related cachexia. Dronabinol is a synthetic compound and its active ingredient is tetrahydrocannabinol. Because it contains THC, it also gives the patient a sense of euphoria, a lapse in short-term memory and an enhanced sensation. This is the only synthetic marijuana-based prescription that is approved by the FDA in the United States.
A big drawback in prescribing marijuana is the physician’s ambivalence to this natural herb. Although traditional medical data supports part of the controversy, the term “medical” does not mean it is without harm, nor does the term “organic” (e.g., hemlock). It is important to differentiate the terms medicinal marijuana with recreational marijuana.
It is proven that adolescent brains are still developing. The frontal lobe does not completely mature until age 25, so recreational use of marijuana can have potential long-term effects on a teenager’s memory and thought process.
Medicinal marijuana and how it is defined is not incorporated into the medical school curriculum nor is it taught during residency training. Physicians are forced to educate themselves on this matter with the confounding findings that smoking marijuana (link is external) results in a much higher (up to five times) level of carboxyhemoglobin and four times more tar than cigarettes, according to a report from the British Lung Foundation titled, “The impact of cannabis on your lungs.” Obviously, not all medical marijuana will be smoked. Nevertheless, when bogged down with patient overload, insurance battles and paperwork, finding the time to better understand this issue, take a stance and then incorporate this into one’s medical practice becomes challenging.
With controversial topics such as medicinal marijuana comes much debate and clinical research. Currently multiple studies are underway to further test the efficacy of medicinal marijuana in the medical world and only time will tell if this can potentially be the next cure for cancer or a non-opiate substitute for pain treatment.
As neurosurgeon and CNN chief medical correspondent, Sanjay Gupta, M.D., wrote (link is external): “It doesn’t have a high potential for abuse, and there are very legitimate medical applications. In fact, sometimes marijuana is the only thing that works. … [I]t is irresponsible not to provide the best care we can as a medical community, care that could involve marijuana. We have been terribly and systematically misled for nearly 70 years in the United States, and I apologize for my own role in that.”
“Arena Pharmaceuticals Reports Favorable Results from Phase 1 Single-Ascending Dose Clinical Trial of APD371.” San Diego, CA: Arena Pharmaceuticals Inc., April 29, 2015.
West, John B. “Respiratory physiology: The essentials (link is external).” Ninth Edition. Baltimore, MD: Lippincott Williams & Wilkins, 2012.
Contributed by Kristen Fuller, M.D.