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Medicinal Cannabis – an Old Crop Turns Over a New Leaf

“Medicinal cannabis” is often used as a broad catch-all term used for any kind of cannabis-based medicine used to provide a therapeutic effect, rather than for purely recreational use. Human beings have been using cannabis for medicinal purposes for thousands of years. Indeed, cannabis appears in the oldest Chinese pharmacopoeia from around 100 AD and is one of the fifty fundamental herbs in Chinese medicine. In Victorian Britain, cannabis was available as an over-the-counter medicine and was used to treat muscle spasms, convulsions, menstrual cramps, rheumatism and also as a sedative. In a number of countries, including the UK and the USA, the twentieth century saw a transition towards the situation in which the possession and distribution of cannabis was criminalized, whilst other drugs were developed to treat the conditions for which cannabis was previously used. A number of the medicinal effects of cannabis recognized today can be traced back to much earlier uses, including pain relief, relief of intraocular pressure and prevention of muscle spasms.

The cannabis plant contains hundreds of different chemical compounds. Moreover, the exact amounts of these compounds present may vary widely depending on the genetic makeup of the cannabis plant in question and the environmental conditions under which it has grown. Such compounds include cannabinoids and terpenes. Cannabinoids are thought to be unique to cannabis and are the principal active ingredients in cannabis-based medicines. The most well-known cannabinoids include tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is one of the key substances in cannabis which impart mind-altering psychoactive effects. However, THC also plays a role in other, more therapeutically useful effects such as reducing nausea, reducing pain, and improving sleep and appetite. THC activity is mediated by activation of the CB1 receptors in the central nervous system. CBD, which is not regarded as psychoactive, does not show any significant activity on CB1 receptors. CBD does show medicinal benefits of its own, in particular in treating pain, diabetes, cancer and neurodegenerative diseases, and potentially also epilepsy, insomnia and social anxiety disorder.

In the UK, the Psychoactive Substances Act 2016 criminalizes the production, supply and possession of “psychoactive substances”. A “psychoactive substance” is defined as being anything which "is capable of producing a psychoactive effect in a person who consumes it" and which is not an exempted substance. Notable exceptions to this law include alcohol, tobacco, caffeine and licensed medicines. The earlier Misuse of Drugs Act 1971 explicitly lists cannabinol and cannabinol derivatives as class B drugs. As a consequence of the drafting of UK legislation, CBD oil is legal in the UK, as it is not psychoactive and can be purchased in health food stores without a prescription. However, cannabis oil containing THC is illegal in the UK.

In recent times, public pressure has brought the use of medicinal cannabis into the spotlight. One example is that of Charlotte Caldwell, who brought seven bottles of cannabis oil back from Toronto which were confiscated at Heathrow airport. Charlotte was using the oil to treat her son, Billy, who had a very severe form of epilepsy. Following the Heathrow incident, Charlotte campaigned to open up patient access to publicly funded cannabis prescriptions. Campaigns such as Charlotte’s prompted a relaxation of the rules around cannabis-derived medicines in the UK in 2018. A number of other countries in Europe have also made steps towards relaxing the rules around the use of medicinal cannabis.

However, the availability of such medicines is still extremely tightly controlled in the UK. Only specialist doctors can prescribe cannabis-based medicines, and only in very specific circumstances. These circumstances include in children and adults with rare, severe forms of epilepsy, adults with vomiting or nausea caused by chemotherapy and people with muscle stiffness and spasms caused by multiple sclerosis. Interestingly, the list of situations in which such products may be prescribed today bears a remarkable resemblance to the known historical uses of cannabis as a medicine.

A number of cannabis-based medicines have come to market and are prescribed in the UK. One such example is Epidyolex (G W Pharmaceuticals), a CBD oral solution which has been through randomized controlled trials for two forms of epilepsy. Another example is Sativex, an oromucosal spray containing both THC and CBD, which is used for treat multiple sclerosis-related spasticity. Man-made synthetic variants of THC Dronabinol and Nabilone have been used for some time to treat chemotherapy-induced nausea and vomiting.

The opening up of this area of medicine raises a number of questions and issues. For modern day medicinal products, there are various standards which must be met in terms of patient testing and standardization of products. Medicinal cannabis products often result from processing a cultivated plant to a natural product or extract. For herbal or botanical products which use extracts or parts of cannabis plants, rather than pure forms of a single compound (“single-entity agents”), standard production methods must be introduced to ensure product consistency and patient safety. There is also the issue of the complex interactions between the existing criminal law and the need for patients prescribed such products to access them, and also for manufacturers to grow and process cannabis plants without fear of prosecution.

In terms of intellectual property rights, despite the use of cannabis in medicine being known for thousands of years, there is a rich seam of innovation to be mined which is potentially eligible for protection as cannabis production starts to move away from its shady recent past. The notable increase in patent filings mentioning cannabis in the last few years reflects this. Patent applications may, for instance, be directed to upstream agritech applications, including strain selection and cultivation methods. Further along the process, midstream technologies such as extraction, purification, separation and preservation may also be patentable. Finally, protection for more traditional pharmaceutical type subject-matter such as compositions, formulations, compounds, specific indications and dosages may be obtained via the patent system. As increasingly sophisticated breeding and plant biotechnology techniques developed in other crops but not generally used in cannabis because of its legal status are brought to bear, plant breeders rights (PBR/PVP), and patents on new cannabis plants, will also have a key role to play as breeders could seek protection for particular advantageous strains or traits, for instance strains rich in a particular compound, or which grow better in certain conditions.

Article by: Hannah Buckley | 2 September 2021

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