🟢Your healthcare espresso shot Vol. 14
An introduction to the Endocannabinoid System and the evidence on Medical Cannabis
💡The structure and function of the endocannabinoid system in the human body are relatively recent discoveries, with the first research published approximately 40 years ago.
🔬🧬The endocannabinoid system plays complex and pleiotropic roles. It is among the key regulators of nervous system development, inflammation and repair. It also serves as a neural signaling pathway that controls processes such as appetite, pain, stress, mood, and other cognitive functions. Additionally, it is involved in maintaining homeostasis (internal balance), in metabolism and energy balance, in inflammatory mechanisms, and in the functioning of other systems, including the respiratory, gastrointestinal, cardiovascular, and musculoskeletal system.
🫀🫁🧠The fundamental mechanism of the system is the binding of endogenous cannabinoids (produced by the body itself) to two receptors: CB-1 and CB-2. CB-1 receptors are the most significant numerically and functionally. They are found primarily in the central nervous system, but also in other tissues such as peripheral nerves, blood vessels, muscles, adipose tissue, and some organs of the gastrointestinal tract. CB-2 receptors are found mainly in blood and immune cells, and to a lesser extent in the anatomical locations where CB-1 receptors are found. The precise role of CB-2 receptors is not yet fully understood. They participate in most of the functions of the endocannabinoid system, but their primary role relates to inflammation after tissue injury. Also of interest is the association of specific polymorphisms (variants) of the CB-2 receptor with conditions such as schizophrenia.
🍀Cannabis contains exogenous cannabinoids (also called phytocannabinoids), which mimic the endogenous ones and bind to CB-1 and CB-2 receptors. Cannabis has therefore been enlisted as a pharmacological intervention. The main phytocannabinoids are tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the primary molecule responsible for the pharmacological effects of cannabis, but it is psychoactive. CBD has markedly weaker effects and is non-psychoactive. CBD can moderate the potent effects of THC by acting antagonistically at the same receptors.
🆘⚠️Every pharmacological intervention has indications, contraindications, risks, and a specific recommended dosage.
✅In Greece, medical cannabis currently has four approved indications:
-Management of nausea and vomiting induced by certain treatments (e.g., chemotherapy)
-Management of spasticity in Multiple Sclerosis and neurological myelopathies
-Appetite stimulation in patients with cancer and AIDS
-Management of chronic pain (e.g., neuropathic or cancer-related pain)
❌Medical cannabis is contraindicated:
-In pregnant women, breastfeeding women and women planning to conceive
-In children and adolescents
-In cases of hypersensitivity (e.g., known allergic reaction) to any of the active substances
-In patients with a history of psychotic disorder
☣️The adverse effects of medical cannabis arise primarily from the nervous system and the gastrointestinal tract. Common adverse effects include dizziness, malaise/fatigue, impaired concentration, blurred vision, drowsiness, dry mouth, and diarrhea.
‼️☢️‼️Additional risks associated with the use of medical cannabis that warrant a mention are the following:
-Potentially serious and dangerous psychoactive effects due to THC
-Risk of addiction and cannabis use disorder
-In the case of dry herb preparations, harmful effects of vaporization
💊In Greece, there are currently ten different medical cannabis preparations available. They require a medical prescription but are not reimbursed by the national health system. All are available in dry herb form for vaporization with appropriate devices. Two of them are also available in oil form for oral consumption. The preparations differ in the cannabis strain from which they are derived, as well as in their THC/CBD concentrations. There are preparations with THC concentration below 1% and with CBD concentration below 1%.
🌿Another significant — though less widely discussed — distinction concerns terpenes. These are naturally occurring aromatic compounds found in many plants. The composition and concentration of terpenes in each preparation can substantially determine the overall effect of that preparation on the human body. For example, some have primarily relaxing and sedating properties, while others may have anti-inflammatory effects or may enhance creativity, memory, and other functions.
👀⏭️And as always, a glance into the future. In other countries, medical cannabis already has more approved indications and applications than in Greece (e.g., rare epileptic syndromes, post-traumatic stress disorder, etc.). Moreover, there is ongoing research on its potential benefits in other conditions, such as inflammatory bowel disease and Parkinson's disease. Furthermore, as outlined above, the endocannabinoid system is involved in a wide range of biological processes. It is therefore not inconceivable that, in the more distant future, the use of cannabis may be studied in various conditions whose pathophysiology involves the endocannabinoid system (e.g., endometriosis-related pain).
🔎🫸In parallel, new safety studies are being published. To date, data link cannabis to an increased risk of bronchial asthma, cardiovascular disease and cardiac arrhythmias. Research is also underway into the effects of cannabis on the social behavior of adolescents and young adults, as well as its association with depression.
💎Key take-home messages:
-This publication deals exclusively with the use of cannabis for medical purposes and has no connection whatsoever with the so-called recreational use.
-The use of medical cannabis requires responsible medical guidance and monitoring.
-There is a legal framework for the possession, transportation and location of use of medical cannabis. Patients are obligated to be informed of and to comply with this framework.
📖References
-Lu HC, Mackie K. An Introduction to the Endogenous Cannabinoid System. Biol Psychiatry. 2016 Apr 1;79(7):516-25. doi: 10.1016/j.biopsych.2015.07.028. Epub 2015 Oct 30. PMID: 26698193; PMCID: PMC4789136.
-Hsu M, Shah A, Jordan A, Gold MS, Hill KP. Therapeutic Use of Cannabis and Cannabinoids: A Review. JAMA. 2026 Jan 27;335(4):345-359. doi: 10.1001/jama.2025.19433. PMID: 41296368.
-https://www.sciencedirect.com/topics/medicine-and-dentistry/endocannabinoid-system