Cannabis, commonly referred to as marijuana, comes from the cannabis plant, namely Cannabis sativa, Cannabis indica and Cannabis ruderalis. Cannabis has traditionally been associated with its illegal recreational use but has gained attention following legalisation in Australia in 2016 for medicinal use. The two main cannabis components, cannabinoids, known for therapeutic effects are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Currently in Australia, medicinal cannabis is regulated by both Federal and State Legislation.
Legislation of cannabis
Cannabis cultivation, production/manufacture and distribution is highly regulated at both Federal and State level. Two main legislative schemes operate to regulate cannabis – the Narcotic Drugs Act 1967 (ND Act) and the Therapeutic Goods Act 1989 (TG Act). Under the ND Act, the government controls the cultivation, research and manufacture of cannabis by issuing permits and licenses. Under the TG Act, the supply of and export of medicinal cannabis is regulated by the Therapeutic Goods Administration (TGA), either by registering the product or providing unregistered products through the Special Access Scheme (SAS), Authorised Prescriber (AP) and Clinical Trials (CT) streams. Through the SAS or AP streams, unapproved medicinal cannabis can be supplied to the public on a case-by-case approval.
Types of Medicinal Cannabis
- Pharmaceutical cannabis products that are approved by the TGA
- Standardised cannabis products that are unapproved but overseen by the TGA
- Unregulated and illegal herbal cannabis
Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD)
Although cannabis is made up of more than 100 cannabinoids, the two main components known for therapeutic effects are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Medicinal cannabis products in Australia can contain THC, CBD or combinations of THC and CBD. In addition, trace levels of other cannabinoids and bioactive aromatic compounds such as terpenes may also be present.
THC and CBD modulate their effects by acting on cannabinoid receptors in the central and peripheral nervous systems. The main differences between THC and CBD, is that THC has strong psychoactive effects and is responsible for making a person feel a euphoric ‘high’, whereas CBD does not and is known to dampen the effects of THC.
The therapeutic effects of THC include analgesia, anti-inflammatory, anti-emetic and antioxidant. Therapeutic effects of CBD include anti-epilepsy and antipsychotic.
Indications for Medicinal Cannabis
Indications for therapeutic cannabis use includes treatment in*
- Chronic pain (endometriosis, neuropathy, Parkinson’s)
- Chemotherapy-induced nausea and vomiting
- Neurological disorders – epilepsy, dementia, traumatic brain injury, Parkinson’s disease, Huntington’s disease
- Irritable bowel syndrome (IBS)
- Sleep disorders
- Spasticity – multiple sclerosis, spinal cord injury
- Psychiatric disorders – depression, anxiety, Tourette’s Syndrome,
Post-traumatic stress disorder (PTSD), schizophrenia, drug addiction
*Note that some of these indications currently lack supporting evidence for medicinal cannabis use. The TGA has published a series of clinical guidance documents that give a summary of evidence for a number of indications in which medicinal cannabis has been prescribed.
Side effects of cannabis
The use of cannabis is associated with paranoia, anxiety and psychosis, including hallucinations and delusions. Other side effects include difficulty concentrating, dizziness, ‘spaced out’, drowsiness, loss of balance, and reduced memory. Cannabis is also an appetite stimulant known colloquially as producing ‘the munchies’. Long-term effects of using cannabis include dependence on cannabis, reduced cognitive function, and worsening of schizophrenia or bipolar disorder.
Routes of administration of cannabis
Traditionally, recreational cannabis use is derived from cannabis plant material. Cannabis that is smoked utilises the unprocessed form of cannabis plant referred to as weed. Weed is the dried leaves and buds of the plant and is commonly smoked in hand-rolled cigarettes, joints. Hashish refers to the preparation of cannabis resins into blocks, and hashish oil refers to the oil collected from the resins, and both can be smoked or infused into food known as ‘edibles’.
Modern medicinal cannabis, on the other hand, can be derived from raw cannabis plant material or synthetically produced molecules in a laboratory. Raw medicinal cannabis plant products, i.e. dried-flower products, can only be prescribed to be vaporised using an approved registered vaporising device in Australia. Medicinal cannabis for oral administration can come from plant or synthetic extracts and include liquids, i.e. oils or tinctures which are swallowed or placed under the tongue and oral capsules which are swallowed.
Poison scheduling of cannabis
Under the Federal TG Act, medicinal cannabis products are classified according to the Australian Poisons Standard. State and Territories then adopt the Poisons Standard scheduling into the state/territory jurisdiction level. There may be slight differences in the regulation at the state/territory jurisdiction level.
Cannabidiol-containing products are Schedule 3 (S3) (Pharmacist only medicine) or Schedule 4 (S4) (Prescription only medicine), with all other cannabis products, i.e. pure delta-9-tetrahydrocannabinol (THC) being categorised as Schedule 8 (Controlled drug). Cannabidiol-containing products in S4 must have 98% of the total cannabinoid content from CBD (note that THC can be a component).
TGA registered and unregistered medicinal cannabis products
There are currently only a few TGA registered medicinal cannabis products. This includes Nabiximols (Sativex®), an oromucosal spray approved for spasticity in multiple sclerosis and cannabidiol (Epidyolex®) used in the treatment of childhood epilepsy. The majority of medicinal cannabis remains unregistered but can be accessed by prescribers via the SAS.
Although since 1 February 2021, there has been an S3 classification for cannabis CBD, whereby patients could access products over-the-counter at pharmacies, there is currently no such product on the TGA Registry. Thus, patients seeking medicinal cannabis can only do so with a prescription from a doctor.
Prescribers can prescribe medicinal cannabis for any patient with any condition by applying for the necessary approvals. Note that the TGA may require evidence of specialist support for the proposed treatment. Prescribers wanting to prescribe unregistered medicinal cannabis can do so through the SAS through the TGA. Prescribers need to ensure that any unregistered medicinal cannabis prescriptions clearly identify the product/brand and meet any state/territory prescription requirements for the pharmacist to order/supply the product. Unfortunately, there are current hurdles in the supply chain. If a product in which the prescriber has had approved via the SAS is later found unavailable, the prescriber will need to reapply for a new product.
Cannabis and the Pharmaceutical Benefits Scheme (PBS)
The only cannabis product to be listed on the PBS is Epidyolex®. All other cannabis products are currently available privately, and as such, patients should be made aware of the financial impact of being prescribed medicinal cannabis. The typical medicinal cannabis cost range is approximately $5-$15 a day.
Due to medicinal cannabis only being newly legalised in Australia, there is no doubt current barriers to accessing medicinal cannabis products. In addition, there is currently only limited evidence supporting medicinal cannabis products for various conditions, which comes from a lack of studies/clinical trials. Over time, it is expected that with the emergence of sound data, more medicinal cannabis products will become TGA-approved which will, in turn, allow cannabis products to be easily prescribed and dispensed from pharmacies across Australia. Lastly, with legalisation of medicinal cannabis, there has been recent debate in relation to legalisation of recreational cannabis. A number of countries have already moved to decriminalise cannabis, Netherlands, Canada, Spain, Czech Republic, to name a few, so perhaps there is change on the horizons for recreational cannabis.
- Arnold JC, Nation T, McGregor IS. Prescribing medicinal cannabis. Aust Prescr. 2020; 43: 152-9.
- Atakan Z.Cannabis, a complex plant: different compounds and different effects on individuals. Ther Adv Psychopharmacol. 2012; 2(6): 241-54.
- FreshLeaf Analytics. Australian medicinal cannabis market; patient, product and pricing analysis. Q1 2020. Sydney: FreshLeaf Analytics; 2020.
- Goncalves J, Rosado T, Soares S, Simao AY, Caramelo D, Luis A, et al. Cannabis and its secondary metabolites: their use as therapeutic drugs, toxicological aspects and analytical determination. Medicines (Basel). 2019; 6(1): 31.
- Greydanus DE, Hawver EK, Greydanus MM, Merrick J.Marijuana: current concepts. Front Public Health. 2013; 1:42.
- Mersiades AJ, Tognela A, Haber PS, Stockler M, Lintzeris N, Simes J, et al. Oral cannabinoid-rich THC/CBD cannabis extract for secondary prevention of chemotherapy-induced nausea and vomiting: a study protocol for a pilot and definitive randomized double-blind placebo-controlled trial (CannabisCINV). BMJ Open. 8(9): e020745.
- Owen J, Wijesena S, Brown P. An overview of the current and proposed medical cannabis regulatory regime in Australia. Bird & Bird, 2021.
- Perucca E. Cannabinoids in the treatment of epilepsy: hard evidence at last? J Epilepsy Res. 2017; 7(2): 61-76.
- Rice S, Koziel JA. Characterizing the Smell of Marijuana by Odor Impact of Volatile Compounds: An Application of Simultaneous Chemical and Sensory Analysis. PLoS ONE. 2015; 10(12): e0144160.