Cannabinoids are compounds derived from or based on chemicals found in the Cannabis sativa plant. There are three general types of cannabinoids: herbal cannabinoids, which are found in the cannabis plant; endogenous cannabinoids (‘endocannabinoids’) that are produced naturally in humans and other animals; and synthetic cannabinoids, which are compounds produced in the laboratory. Nabilone (Cesamet®), dronabinol (Marinol®) and THC/CBD (Sativex®) are the three prescription cannabinoids currently available in Canada.
THC and CBD – the most common cannabinoids
The leaves and flowering tops of cannabis plants produce more than 70 different active ingredients called herbal ‘cannabinoids’. The two most active, common herbal cannabinoid compounds are Delta-9 tetrahydrocannabinol (THC) and cannabidiol (CBD) [1, 2].
THC is responsible for most of the known pharmacological actions of cannabis, including the psychoactive effects— meaning that it affects the mind or mental processes. CBD is the most important non-psychoactive component of the cannabis plant.
Cannabinoids mainly exist in their acidic forms in cannabis plant and are converted to THC and CBD through a process called decarboxylation. This process is facilitated by increased temperature which explains why it is important to incorporate a heating method prior to consumption.
Relatively little is known about the pharmacological actions of the various other compounds found within cannabis (e.g. terpenes, flavonoids). However, it is believed that some of these compounds (e.g. terpenes) may have a broad spectrum of action (e.g. anti-oxidant, anti-anxiety, anti-inflammatory, anti-bacterial, anti-neoplastic, anti-malarial), but this information comes from a few in vitro and in vivo studies and no clinical trials exist to support these claims. It is proposed that cannabinoids and terpenoids may form a metabolic “entourage” that is responsible for the bioactivity of cannabis.
There are two main cannabinoid receptors in the human body: CB1 and CB2. These receptors are located in the brain, intestines, and immune system.
The CB1 receptors are found in the central nervous system, in particular the brain, and in other organs and tissues such as the eyes, lungs, kidneys, liver and digestive tract. One of the factors that contribute to the relative safety of cannabis is the virtual absence of cannabinoid receptors in regions at the base of the brain responsible for vital functions as breathing and heart control.
CB2 receptors are primarily located in tissues associated with immune function, such as the spleen, thymus, tonsils, bone marrow, and white blood cells.
Cannabinoid receptors are involved in the regulation of many body functions including: brain and nervous system activity, heart rate and blood pressure, digestion, inflammation, immune system activity, perception of pain, reproduction, wake/sleep cycle, the regulation of stress and emotional state among others .
For a brief video about cannabinoids: Marijuana and Your Brain – A CNN Video. CNN chief medical correspondent Dr Sanjay Gupta explains how cannabis affects the brain.
 “Cannabis (marihuana, Marijuana) and the Cannabinoids Dried Plant for Administration by Ingestion or Other Means Psychoactive Agent.”Information for Health Care Professionals. Health Canada, 12 June 2013. Web. 22 Oct. 2014. http://www.hc-sc.gc.ca/dhp-mps/marihuana/med/infoprof-eng.php
 CONSUMER INFORMATION Cannabis (Marihuana, Marijuana). Ottawa: Health Canada, 2013. http://www.hc-sc.gc.ca/dhp-mps/marihuana/info/cons-eng.php