Overview of Medical Cannabis
The cannabis plant has a long history of human use for purposes including food, fibre and traditional medicine. Historical records describe its use in different cultures, although traditional use does not, by itself, establish clinical effectiveness or safety.
Cannabis is a flowering plant containing hundreds of naturally occurring compounds. These include cannabinoids, a group of substances that interact with biological systems in the human body. Two widely studied cannabinoids are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD).
Cannabinoids and the Endocannabinoid System
The human body has an endocannabinoid system, which is involved in regulating several physiological processes. It includes naturally occurring endocannabinoids, cannabinoid receptors and enzymes involved in the production and breakdown of these compounds.
Two commonly discussed cannabinoid receptors are:
CB1 receptors: Found predominantly in the central nervous system, as well as in some peripheral tissues.
CB2 receptors: Found mainly in immune cells and other tissues, with distribution that varies across the body.
THC can activate CB1 and CB2 receptors, with its interaction with CB1 receptors contributing to its intoxicating effects. CBD has a more complex pharmacological profile and does not act in the same way as THC at these receptors. It can influence several biological pathways, and its effects depend on factors such as formulation, dose and individual physiology.
Plant-derived cannabinoids and naturally occurring endocannabinoids interact with the body's biological systems in different ways. Their effects should not be assumed to be identical.
THC, CBD and Medical Cannabis
THC and CBD have different pharmacological properties.
THC is the principal intoxicating cannabinoid in cannabis. Depending on the product and dose, it may affect perception, coordination, memory and alertness. It can also cause unwanted effects, including anxiety, dizziness and impairment.
CBD is not generally intoxicating in the same way as THC. It has been investigated for several potential therapeutic applications, but evidence varies by condition and product. Some CBD medicines have been approved for specific indications in certain jurisdictions.
The effects of medicinal cannabis depend on the cannabinoid composition, formulation, route of administration, dose, individual characteristics and other medicines being used. A higher quantity of a particular cannabinoid does not necessarily produce a better therapeutic outcome.
Forms and Methods of Administration
Medicinal cannabis products are available in different formulations. The method of administration can influence how quickly a product takes effect, how long its effects last and how much of its active ingredients are absorbed.
Common forms include:
Oral products: Oils, capsules and other formulations taken by mouth. Effects may take longer to develop than with inhaled products.
Topical products: Creams and other preparations applied to the skin. Their effects depend on the formulation and whether the ingredients are intended for local or systemic delivery.
Transdermal products: Patches designed to deliver substances through the skin over a period of time.
Inhaled products: Certain medicinal cannabis products may be administered using a vaporising device. Inhalation can produce a faster onset of effects, but it also involves respiratory and other safety considerations.
Not every formulation or administration method is approved or available in every jurisdiction. Products should be used only as directed by an appropriately qualified healthcare professional.
Safety and Medical Considerations
Medicinal cannabis is not suitable for everyone. Potential risks include impairment, dizziness, changes in mood or perception, interactions with other medicines and other adverse effects. THC-containing products may be particularly concerning for people who need to drive, operate machinery or perform tasks requiring alertness.
The evidence for medicinal cannabis differs between conditions and products. Patients should discuss potential benefits, risks, alternatives and monitoring with a qualified healthcare professional before considering treatment.
Disclaimer: This article is for general educational purposes only and does not constitute medical advice or a recommendation to use cannabis products. Medicinal cannabis access, approved products and prescribing requirements vary by jurisdiction. Do not start, stop or change a medicine without consulting an appropriately qualified healthcare professional.