No doubt you’ve heard about ‘medical marijuana.’ Stories around in the media of children achieving respite from uncontrolled seizures, cancer patient’s nausea and pain relieved, and muscle spasticity from multiple sclerosis eased. More questionable reports have claimed cannabis effective for treating diabetes, cancer and HIV. Despite these claims, all forms of cannabis have been regulated to date as Schedule 9 banned substances such that possession and use throughout Australia was illegal. However, all that is about to change.
Powerful campaigning has pressured politicians and regulators to change the legislation and make cannabis more accessible for medical research. On 31 August 2016, the TGA announced their final decision to down-schedule cannabis and tetrahydrocannabinols (THC) to Schedule 8 from 1 November 2016, which will allow medial research and therapeutic use to go ahead unfettered by legal restrictions.
CANNABIS vs MARIJUANA
Cannabis is a genus of flowering plants that includes a number of species, most frequently Cannabis sativa and Cannabis indica. There is no plant named ‘marijuana’ so, from a botanical point of view, ‘cannabis’ is the correct term of use. ‘Marijuana’ is used to describe the dried flowers and leaves of the cannabis plant. Hemp is that name given to the male cannabis plant that produces low levels of THC is used for production of fibre and oil.
Cannabis has an extensive history as a medicinal agent across many cultures and civilisations. Early Chinese accounts dating back to the Emperor Shen-Nung (c2700BC) cite cannabis as an important herbal remedy. Sir Joseph Banks, the botanist on Captain Cook’s 1770 voyage to Australia, is credited with bringing the first recorded cannabis seeds to Australia.
SO WHAT IS MEDICINAL CANNABIS?
There is no agreed definition of ‘medicinal cannabis’ nor a specific product. The term actually relates to a range of cannabis derivatives which fall into three categories:
- Crude plant products (e.g. marijuana, hashish and cannabis oil)
- Natural cannabinoids (e.g. THC and cannabidiol) and
- Synthetic cannabinoids (e.g. dronabinol or nabilone).
Due to the historical prohibition of cannabis, research into cannabinoid pharmacology has only occurred fairly recently. The first human cannabinoid receptor, CB1, was only discovered in 1988 and the endogenous agonist for CB1 and CB2 receptors called anandamide, an omega-6 fatty acid neurotransmitter, was discovered in 1922. The name anandamide is taken from the Sanskrit word Ananda, which means “joy, bliss, delight.”
The fact that we have endogenous cannabinoids and several cannabinoid receptors throughout our central nervous system suggests cannabinoids play an important role in human physiology, otherwise they would have evolved away centuries ago.
WHAT EVIDENCE SUPPORTS THERAPEUTICS BENEFIT?
Overall, regulatory authorities have taken the view that cannabis is not a panacea but definitely carries therapeutic potential. Research evidence supporting medicinal cannabis is so far thin on the ground but many clinical trials are underway.
The therapeutic uses fall into five main areas: muscle spasticity in multiple sclerosis, chemotherapy-induced nausea and vomiting, loss of appetite in palliative care, chronic pain and epilepsy. THC is largely responsible for the psychiatric effects of cannabis, both good and bad, but it is also claimed to provide the analgesic relief and muscle relaxing properties of cannabis. Cannabadiol is thought to convey the anticonvulsant effects, and has shown impressive results in some rare forms of intractable epilepsy. It is given as a 98 per cent CBD product in oil called ‘Epidiolex’ that a child takes orally. Another anticonvulsant cannabis derivative called cannabidivarin is currently the subject of clinical trials in New South Wales.
Nabiximols is a whole-plant botanical extract of cannabis, administered as a mouth spray, containing THC and CBD in approximately equal proportions. The trade name for nabiximols is ‘Sativex’ and has been registered for use in Australia for several years. Nabilone and dronabinol are synthetic cannabinoids that have been marketed since the 1990’s in Australia and overseas as oral tablets but have never been clinically successful.
You may have noticed by now that there has been no mention of smoke-able cannabis for medicinal use. Due to the well-known adverse effects of smoking, only non-smokeable cannabis products will be supported by the TGA for medicinal purposes. What form these take may range from tablets, oils, edibles and maybe vaporisable products.
SO HOW WILL PRESCRIBING AND DISPENSING WORK?
This is the hard part. Currently, there is no infrastructure to support prescribing or dispensing of cannabis outside of clinical trials and the TGA’s Special Access Scheme. No one even knows what a cannabis prescription would look like! However, in the future regulatory authorities have made it clear they will only allow authorised medical specialists to initiate medicinal cannabis treatment and specially trained and authorised general practitioners to continue prescribing it. Only authorised pharmacists will be permitted to dispense it, although it is not known yet how the cannabis will be accessed, but it looks like only Australian-grown cannabis products will be permitted. Many details around manufacture, shelf-life, and storage, record-keeping and reporting are yet to be ironed out.
INDICATIONS POTENTIALLY OF MOST INTEREST
- Multiple sclerosis
- Chemotherapy-induced nausea and vomiting
- Cancer pain
- Palliative care
- AIDs nausea and vomiting
- Refractory epilepsy
- Neuropathic pain
- Inflammatory bowel disease
- Psych conditions, e.g. PTSD
- Rheumatological conditions
- Glaucoma
- Tourette syndrome
Source: Australian Dental Association News Bulletin