An overview of
medical cannabis

The medical cannabis debate has been escalating in Australia for several years. This factsheet touches on some of the research conducted, and highlights where further research is needed.

Following the legalisation of cannabis for medicinal purposes in a number of US states over the past two decades, debate in Australia has intensified about the benefits and drawbacks of potential legalisation of cannabis for medicinal use only. Limited research has been undertaken on the effectiveness of using cannabis in its natural state for medicinal purposes, and none has occurred on the many types of high potency edibles (e.g. brownies, soft drink, lollipops, ice cream) sold in US dispensaries. More is known, however, about the risks, benefits and effectiveness of pharmaceutical preparations of cannabinoids (chemicals unique to the cannabis plant).

History of cannabis as a medicine

Before modern medicine, cannabis extract was used in Europe and the US in the 1800s to treat menstrual cramps, asthma, cough, insomnia, labour pain during birth, migraine, throat infection and withdrawal from opiate use. Due to various reasons, cannabis was eventually removed from the register of medicines in the 1920s and made illegal around the same time.

Over the past 20 years, there has been increasing international focus on the potential of cannabis (or components of the drug) as a second-line treatment option for various medical conditions where the most effective medication is not working well. The most common conditions linked with cannabis use for symptom relief include pain and nausea associated with cancer and its treatment, HIV and other wasting diseases, rheumatoid arthritis and peripheral neuropathic pain, and to a lesser extent, nightmares associated with post-traumatic stress disorder. Despite being illegal in Australia, cannabis has been reported by users to help alleviate pain, nausea, loss of appetite and spasticity associated with some of these conditions. Of the recent published trials, many have found short-term benefits from pharmaceutical preparations of cannabis components, however longer-term trials are needed in order to comprehensively gauge the therapeutic benefits.

Over the last decade, cannabis has been made available for medicinal purposes in 24 US states with nine pending legislation, but with extremely limited controls on the quality, dosage or safety of the product or its delivery system. It is not often well understood that this legislation arose from citizen-initiated referenda, and not from the culmination of scientific evidence and consensus processes used for other medications. It is not prescribed in the way other medications are as doctors have no evidence-based guidelines to follow for dose, duration of use, or likely interaction with other medications. It is a legislative approach where doctors provide a registration card or similar paperwork allowing the person to purchase (in some states grow) and possess cannabis. It is not medically monitored once the cannabis is obtained.

Cannabinoids

Though the word cannabinoid initially referred to the naturally-produced chemicals of the cannabis plant, subsequent advancements in development of synthetic chemicals has expanded the definition. There are three broad types of chemical compounds now known as cannabinoids:

  1. phytocannabinoids (plant forms)
  2. endogenous cannabinoids (produced naturally in the bodies of humans and animals), and
  3. synthetic cannabinoids that are man-made chemicals, not derived from plants.

Within the cannabis plant, some cannabinoids, such as THC have a psychoactive effect. Others, such as CBD, do not have this effect, and have been linked with anti-anxiety, anti-epileptic and antipsychotic effects in addition to other potential uses.

For more information about cannabinoids, see our factsheet.

Cannabis as medicine

Almost all of the modern research literature on cannabinoids as medicine has used pharmaceutical preparations of THC or CBD and even this is not far-reaching. There have been no published human trials that use the accepted gold standard study design using whole smoked plant. Pharmaceutical preparations have been used to treat the following conditions with varying levels of effectiveness:

  • Chronic/acute pain Cannabis preparations have been used to treat many types of pain including chronic unexplained pain, rheumatoid arthritis, pain associated with Multiple Sclerosis (MS) and cancer among others. While the studies have revealed benefits of the drug, more testing is required due to potential self-selection bias and recorded side-effects. Pharmaceutical preparations of cannabis have been legalised in some countries for some of these illnesses, including MS.
  • Nausea and vomiting in patients with cancer or HIV Synthetic preparations have been used to help ease nausea and vomiting in these groups and to stimulate appetite. The drug has been shown to relieve symptoms despite more intense side effects, but a Cochrane review concluded more evidence is needed.
  • Spasticity, muscle cramps and nerve pain associated with Multiple Sclerosis and Parkinson s disease While results have been somewhat mixed in studies, nabiximols (Sativex) has been used relatively successfully to treat spasm symptoms and is available in some countries where other treatments haven t worked.
  • Glaucoma Existing treatments have so far proven more effective for Glaucoma patients who typically only have very short-term relief when using cannabis, and experience unwanted side effects as they have to use often.
  • Cannabis withdrawal Though more research is required,Nabiximols has been trialled in Australia for the management of cannabis withdrawal and this has been found to be safe and effective.
  • Epilepsy CBD has been shown to have anti-convulsive properties but more human research is needed. Trials are underway looking at CBD for the management of severe early-life seizures.
  • Inflammatory bowel disease While anecdotal reports of effectiveness exist, no clinical trials have yet occurred.

The bottom line

While further studies and trials are starting to take place, to-date there is not enough evidence to confirm or deny the potential medical uses of cannabis or its components. When considering legalisation and support or opposition for medicinal cannabis, Australians must consider the vital need for further research to confirm effectiveness and also short and long-term side effects, further regulation to combat social issues or safety issues such as driving, storage issues to prevent use by young children, as well as how the drug may be administered, as smoking has been associated with respiratory illness. In addition, consideration should be given to the potential for users to experience addiction, physical and psychological effects especially in those whose brains are still in developmental stages such as children and youths.

Though components of cannabis may be effective treatments for some illnesses, the bottom line is that pharmaceutical preparations currently offer the only opportunity for delivering a safe, tested and regulated medicine for which doses can be controlled, but in general, more research needs to be done to decrease the unknowns.