Medical Cannabis
What is a cannabis plant?
Traditionally, before modern interbreeding produced thousands of hybrid strains, there were two main types of cannabis plants – Cannabis sativa and Cannabis indica and a third subspecies called ruderalis. They were said to have somewhat different recreational effects, sativas being thought of as more ‘energizing’ and indicas being thought of in popular culture to be more ‘sedating.’ But in medical terms, and certainly even more so because most medical cannabis strains are hybrids, it is best to focus on the proportion of the different cannabinoids.
This is a more accurate system of classification known as chemovar (i.e. the mix of cannabinoids) classification. The cannabinoids are most concentrated and produced in highest amount in the unfertilised female flower. The cannabinoids in the plant are in their acidic form (such as THCA (tetrahydrocannabinolic acid) and CBDA (cannabidiolic acid)). Whilst the acidic cannabinoids have some medical properties, they are less studied and understood clinically. Therefore, currently for medical use the plant material is usually heated to decarboxylate the acid forms into ‘active’ forms in most capsules and oils (e.g. from THCA to THC and CBDA to CBD). If dried flower is prescribed (as in Canada and Germany, for example) then it is important to remind the patient that decarboxylation by heating is usually required before use, as is using a vape, for example. Acidic cannabinoids are not psychoactive
What are cannabinoids?
The plant contains about 120 cannabinoids. The best known are THC (tetrahydrocannabinol) and CBD (cannabidiol). The former is the main psychotomimetic/ psychotropic cannabinoid and the latter is anxiolytic and counteracts the THC psychotomimetic/intoxicating effects.
Most medical studies have been conducted focusing on these two cannabinoids. The other cannabinoids studied also have medical properties. THCV, for example, (tetrahydrocannabivarin) is known to have marked anti-obesity effects in animal models.
Some are psychomimetic/psychotropic and some are not. The content label of the product should indicate the amount of the other “minor” cannabinoids but at the moment most emphasis will be on the proportions of THC and CBD. In the future, this may evolve to include more specifics about the other cannabinoids as more research in humans emerges.
What are terpenes?
Terpenes give cannabis its characteristic smell and flavonoids give colour. They also have medicinal properties although the published research in humans elucidating the details is still very preliminary in the cannabis plant.
Some patients are aware that they prefer a particular strain with a certain mixture of terpenes and minor cannabinoids, which matches with anecdotal clinical observations from prescribing in other jurisdictions where medical cannabis has been more widely prescribed, such as in Canada.
The MCCS recommend that labelling of products includes at least the terpene profile so that our understanding of the value of these components can develop over time, and possibly included in any clinical data collection
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The most common terpene in cannabis. Studies suggest this terpene to promote calming effects. |
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Most common terpene in the natural world. Studies show it may be help with pain, inflammation, or anxiety. |
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Only known terpene to also act as a cannabinoid. Can activate our ECS to provide anti-inflammatory effects Caryophyllene has the following potential medical benefits: |
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May provide anti-inflammatory benefits Humulene’s other potential effects include: |
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Believed to promote sedating and calming effects. |
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Believed to provide relief from stress and anxiety. |
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Sweet, earthy and citrusy aroma frequently used in perfume. |
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About on in ten strains are dominant in terpinolene. Believed to have uplifting effects. |
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This secondary terpene is believed to produce sedating effects, and is being investigated for the following medical benefits:
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What is the endocannabinoid system (ECS)
This is the neurotransmitter system contained throughout the human body. There are natural endocannabinoid receptors (CB1 and CB2) found in the nervous and immune systems and elsewhere. There are natural ligands to these receptors (anandamide and 2-AG). The ECS is known to have a wide range of effects.
The phytocannabinoids found in the plant are thought to work through the ECS (and other neurotransmitter systems). There is now a wide range of information available about the science of the ECS.
The MCCS recommends that doctors familiarise themselves with at least the basics of this system in order to better understand the plant / human interaction
