What is medical cannabis?
In very simple terms, medical cannabis is prescribed specifically to alleviate the symptoms of an illness. Medical cannabis needs to be prescribed by a doctor for a particular condition.
The therapeutic properties of the cannabis plant come mainly from the cannabinoids naturally occurring in the plant. There are between 80 and 144 cannabinoids present in the cannabis plant- the two main cannabinoids that have been found to have therapeutic effects are tetrahydrocannabinol (THC) and cannabidiol (CBD). Many of the therapeutic effects of THC and CBD are thought to be the result of their interactions with the endocannabinoid system.
The endocannabinoid system (ECS) is a complex cell-signaling system discovered in the 1990s. As a result of this discovery, it was found that the ECS regulates multiple physiological processes involving the immune system, the nervous system, and metabolism. It also discovered cannabinoid receptors (CB1 and CB2) are scattered throughout your central and peripheral nervous system. Additionally, it found that naturally occurring cannabinoids (endocannabinoids) bind to the CB1 and CB2 receptors to exert an influence on various physiological processes. Furthermore, it was established that exogenous cannabinoids such as THC and CBD were able to bind to cannabinoid receptors in a similar way to endogenous cannabinoids.
THC is responsible for the ‘high’ often associated with cannabis due to its psychoactive properties. CBD does not create a ‘high’ and, when taken in conjunction with THC, can mitigate some of THC’s negative effects such as anxiety.
Medical cannabis can be specifically formulated to contain different ratios of THC:CBD allowing prescribers to tailor each patient’s treatment depending on their condition. This is in contrast to recreational cannabis, which is unregulated, and often contains very high levels of THC in order to maximize the ‘high’.
What conditions can medical cannabis treat?
The list of conditions that have shown benefits from medical cannabis is growing rapidly as more and more research is being published. Therefore, the following list will grow considerably as the plant is more widely studied and prescribed.
The range of medical conditions that respond to medicinal cannabis is likely to increase as further research takes place.
You're prescribed medical cannabis, now what?
There is more than just safety and efficacy to consider when prescribing medical cannabis, however.
The following also need to be considered:
Start low and go slow: It is important to remember the maxim ‘start low, go slow’ when initiating treatment with medical cannabis. Tolerance to THC is patient-dependent depending on a range of factors including age, metabolism, pre-existing illnesses/medications, and prior THC use. Therefore, starting at a low dose and titrating up as necessary to achieve the desired result ensures that any potential side effects are avoided or minimized.
Delivery method: Medical cannabis products come in various delivery methods, such as oils, sublingual sprays, capsules, creams, etc. Therefore consider what is available, which delivery methods are acceptable and which delivery methods are most efficacious for the medical condition being treated.
Formulation: Medical cannabis can potentially come in different ratios of THC:CBD. Ideally, one would want to be able to choose from the following: a high THC: low CBD ratio, a balanced THC:CBD ratio, and a high CBD: low THC ratio, depending on what medical condition is being treated. It is also useful to have CBD-only formulations for those patients who are wary of THC or when THC is contraindicated. The following table can give an indication of various uses of different ratios of THC:CBD:
Cost: Certain medical cannabis products on the market are prohibitively expensive, so check the cost before making a decision on a product.
How safe is medical cannabis?
It is reassuring to know that medical cannabis is well-tolerated and generally considered safe. Furthermore, a 2020 review of the scientific evidence for the use of THC:CBD oromucosal spray for the management of chronic pain showed no new safety concerns with long-term THC:CBD use. The review also showed no evidence of dependence. This finding supported the findings of a 2019 study that found medical cannabis, especially CBD-only formulations, to have minimal side effects.
Although medical cannabis is a very safe option for most people, there are some contra-indications to be aware of. THC and CBD are metabolized via the cytochrome P450 (CYP450) pathway. As a result, medical cannabis is contraindicated in people with disorders of CYP450 enzymes.
Medical cannabis can interact with certain medications so care should be taken when medical cannabis is prescribed with any of the following medications: warfarin, ketoconazole, clobazam, theophylline, olanzapine, and clozapine, opioids, anticholinergics, and certain antihistamines.
In summary
Patients can use medicinal cannabis for the treatment of a growing list of medical conditions. Due to that growth, this list will likely expand as more research is published. Furthermore, medical cannabis is considered safe and is generally well-tolerated with little risk of dependence.
The strict regulations in place around the registration of medical cannabis products in New Zealand should ensure that doctors feel confident when prescribing medical cannabis that they are prescribing a safe and efficacious product. You should take care when prescribing to choose the optimum delivery method and formulation specific to your patient.