The Premier of NSW has proposed that a four year trial of the medicinal use of cannabis be conducted in NSW.⁽¹⁾ This research note examines the background to the medicinal use of cannabis, recent overseas experience, and areas of possible Commonwealth involvement with the NSW trial.

The Proposed Cannabis Trial

The proposal for a trial follows an advisory report commissioned by the NSW government, and a public consultation process. In line with the advisory report's recommendations, cannabis would be prescribed in the trial for (i) the relief of chronic or severe pain in patients for whom other palliative and analgesic treatments have proven unsuccessful; and (ii) the relief of symptoms of certain medical conditions for which cannabis has been shown to have therapeutic benefits, including:

It is proposed that patients would register with an Office of Medical Cannabis in the NSW Department of Health, and provide a certificate from their long-standing medical practitioner that conventional treatments have been unsatisfactory. Those not eligible for the trial would include people under 18 years of age, pregnant women, people on parole, and those who have been convicted of a drug offence (other than for minor personal use).

There are different ways of providing cannabis for the trial. The NSW Premier has indicated a particular interest in an oral spray that has been trialled in the UK over the past three years.⁽²⁾

The Therapeutic Evidence

There is debate about the therapeutic effectiveness of cannabis. It is generally agreed, however, that there is sufficient pre-clinical evidence to justify conducting more extensive controlled clinical trials. The beneficial actions attributed to the active components of cannabis are:⁽³⁾

The most recent survey of the evidence⁽⁴⁾ suggests that the most promising therapeutic uses for cannabis are in the management of chronic pain which is unresponsive to standard analgesics, and also in the management of spasticity associated with multiple sclerosis. Cannabis may also slow the progress of degenerative neurological conditions, such as Parkinson's disease.

Some studies warn against over-optimism, noting that cannabis may, in some cases, have no greater effect on chronic pain than existing analgesics.⁽⁵⁾

Adverse Effects

Cannabis is known to have adverse effects, including short-term impairment of motor-coordination, attention span and memory. The effects of longer-term smoking of cannabis include low level cognitive impairment, as well as the possible inducement or exacerbation of psychotic disorders in individuals vulnerable to them. It is unclear whether cannabis causes psychosis, or whether people with incipient psychosis are using cannabis as a form of 'self-medication' to relieve symptoms. However, very recent evidence does not support the 'self-medication' view.⁽⁶⁾ There is also emerging evidence that heavy cannabis use is linked with depression.⁽⁷⁾

In a clinical trial, the occurrence of adverse effects is monitored, as well as the positive therapeutic ones. A medical practitioner will take potential 'unwanted' effects into account when deciding whether a patient will benefit on balance from cannabis therapy.

Overseas Experience

The International Narcotics Control Board has encouraged research into the therapeutic possibilities of cannabis.⁽⁸⁾ Canada and the US states of Oregon, Alaska, Hawaii and California⁽⁹⁾ have recently adopted laws allowing the medicinal use of cannabis. The Netherlands has recently made cannabis available on prescription from pharmacies.

In all these cases, a physician's recommendation is required. The medical conditions for which cannabis is supplied in these overseas locations are generally the same as those for which it will be available in the NSW trial. In the US states, patients use cannabis they acquire or cultivate themselves. Canada and The Netherlands are making pre-packaged therapeutic grade cannabis available to patients.

In Canada, there have been 582 approved medical cannabis users as of July 2003 (0.002% of its population). This is a 54% increase since its inception in July 2001.⁽¹⁰⁾ Of the total population of Oregon, Alaska and Hawaii, 0.05% (2,454 people) were registered as medical cannabis users, as of September 2002.⁽¹¹⁾

Commonwealth Involvement

The NSW trial would need reliable access to research grade cannabis. Cannabis is not currently approved by the Therapeutic Goods Administration (TGA) for therapeutic use in Australia. Application or notification needs to be made to the TGA to exempt the supply or importation of cannabis from restriction. A medicinal cannabis trial must be approved and monitored by an appropriate Human Research Ethics Committee, in accordance with National Health and Medical Research Council guidelines. The TGA must also be assured of the safety of the trial. Under certain conditions, if the TGA becomes aware that a trial is 'contrary to the public interest', it can direct that the trial not be conducted.⁽¹²⁾

Various other Commonwealth laws may need to be considered in the conduct of a medicinal cannabis trial. Depending on how cannabis is to be supplied for the trial, these might include the Customs Act 1901, the Narcotic Drugs Act 1967, and the Crimes (Traffic in Narcotic Drugs and Psychotropic Substances) Act 1990. The Commonwealth has extensive constitutional power to legislate in relation to drugs, including illicit drugs.

Sending the Wrong Message?

It is sometimes argued that to allow an illegal substance like cannabis to be legally used in certain contexts, sends a 'wrong' or 'mixed' message. It might be thought that this weakens the deterrence that a legal prohibition of cannabis might have, and therefore acts to increase cannabis use, particularly among young people. Some brief observations can be made about this.

These three observations do not support the view that trialling the medicinal use of cannabis will have the detrimental impacts thought to be associated with sending a wrong or confusing message.