Medicinal cannabis

Tracey Sullivan Pharmacy Features Writer

Medicinal cannabis or ‘medical marijuana’ is the term used to refer to all forms of cannabis used in the treatment of medical conditions or disease symptoms. It is different to recreational cannabis where people use cannabis to get ‘high’.

The cannabis plant

The cannabis plant (Cannabis sativa) has a long history of human use – for medicine, food, fibre, rope, in ancient religious ceremonies and for recreational use. The cannabis plant contains chemicals called cannabinoids which are naturally occurring compounds with a wide range of therapeutic properties. Well over 100 cannabinoids have been identified. The two main cannabinoids found in the cannabis plant are tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is psychoactive and gives the euphoric effects that recreational drug users expect, however, THC also has many potential therapeutic benefits. CBD has little to no psychoactive properties and is better known for its medicinal benefits.

The human body has its own cannabinoid chemicals called endocannabinoids. These chemicals have effects on pain, mood, inflammation and anxiety. There are many receptors for these chemicals in major organs like the brain, skin and liver and these are what respond to medicinal cannabinoids. Medicinal cannabis interacts with these receptors to cause health benefits.

Benefits of medicinal cannabis

Medical research has shown medicinal cannabis to have the ability to decrease pain and inflammation, increase appetite, decrease nausea, enhance the feeling of wellbeing and help with psychoactive disorders. It is widely used internationally in pain, palliative care and oncology settings because of these therapeutic benefits. In New Zealand medicinal cannabis is most commonly prescribed for pain, sleep, mental health conditions, nausea and vomiting from chemotherapy and for neurological conditions such as epilepsy and multiple sclerosis.

Medicinal Cannabis Scheme

In New Zealand the Misuse of Drugs (Medicinal Cannabis) Regulations came into force on 1 April 2020 and the Medicinal Cannabis Scheme was introduced. The Scheme lifted the regulatory barrier to prescribing medicinal cannabis. It aims to improve patient access to medicinal cannabis products. Before the legislation change it was rare for a medical practitioner to prescribe medicinal cannabis. Now, it can be prescribed by any doctor for any medical condition, within the doctor’s scope of practice. As it is a prescription medicine, sourcing medicinal cannabis online or by other means without a prescription is illegal. Medicinal cannabis medicines are not subsidised and are considered high-cost medicines.

Medicinal cannabis products are only available on prescription if certain conditions have been met. A product either has to be approved by Medsafe as a medicine after being assessed for safety and efficacy. The Medsafe approval process analyses pharmacological data and the results of clinical trials in humans. Alternatively, the product has to be verified against a set of minimum quality standards that are set by the Ministry of Health. Meeting these standards gives assurance that the product has been manufactured to Good Manufacturing Practice (GMP), and meets standards to prevent contamination and adulteration. So far, there has only been one pharmaceutical grade cannabis medicine approved by Medsafe. This medicine has been approved for add on treatment of multiple sclerosis, for patients with moderate to severe spasticity.

Side Effects

Medicinal cannabis is generally considered safe and is well tolerated by most people. Research shows there is little risk of dependence.

Like most medicines, there are interactions to be aware of between other medicines such as warfarin, opioids and certain antihistamines. Most common side effects are excessive sleepiness, diarrhoea and fatigue or weakness. Medicinal cannabis products with a high THC content can cause postural hypotension leading to falls or anxiety, and other cardiac events.

The future

There is a growing range of conditions that medicinal cannabis can be used for, and an increasing amount of research showing its value in therapeutic use.

Emerging evidence indicates that medicinal cannabis may be useful for both osteoarthritis and rheumatoid arthritis, migraines, muscle tension, joint pain, depression and chronic pruritis associated with contact dermatitis, eczema and psoriasis. The list of conditions will continue to increase as cannabis is more widely studied and medical practitioners prescribe it more.

Your GP and pharmacist are important sources of information regarding the use of medicinal cannabis. It is very important to remember that medicinal cannabis is not a first-line treatment for any medical condition. Established medical treatments will always be considered first as a treatment option, however, there is great potential for medicinal cannabis to be trialed where other treatments may not have worked.

This blog provides general information and discussion about medicine, health and related subjects. The information contained in the blog and in any linked mate­ri­als, are not intended nor implied to be a substitute for professional medical advice.

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