Medical Marijuana in Canada

Cannabis has been used therapeutically by many cultures throughout the world for at least 4,000 years.  It was commonly used in this manner in mainstream Western medicine during the 19th century.

Interest in its use as a medicine re-emerged in the 1970s as it began to be used to treat a wide range of conditions, including cancer, HIV/AIDS, multiple sclerosis, arthritis, epilepsy, glaucoma and many others.

In Canada, while "cannabinoid research" is a relatively new and underdeveloped field, "medical marijuana" use is significant and is legitimized by federally funded Health Canada access and research programs.

Despite the long history of medicinal use, the scientific mechanism of how and why cannabis works in the body has only been better understood in the past 20 years. New scientific techniques have enabled reseachers to determine that there are more than 460 chemical constituents in the cannabis plant, of which more then 60 are unique to cannabis plants and have since been classified as "cannabinoids". Delta-9-tetrahydrocannabinol (THC) is the best understood of these cannabinoids. These cannabinoids have a varying degree of activity on recently discovered "cannabinoid receptors", of which at least two are known to exist, CB1 and CB2. These receptors can be found throughout the human nervous system and in the immune system.

Reseachers have also discovered that the human body produces its own cannabinoid chemicals that act on these receptors called "endocannabinoids". When external cannabinoids (from the cannabis plant or cannabinoid based drugs) or endocannabinoids act on these receptors, they active the "retrograde signaling pathway", a key mechanism by which cannabinoids work in the central nervous system.

Although knowledge of cannabinoid pharmacology as well as the chemical composition of the cannabis plant has advanced dramatically in recent years, more research is required to determine how each cannabinoid works and how cannabinoids interact and modify each others properties.  Developing this understanding is essential for broader application of cannabis in a medical context.