eMJA: Hall et al, Allowing the medical use of cannabis

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Allowing the medical use of cannabis

Cannabis has been advocated as a treatment for nausea, vomiting, wasting, pain and muscle spasm in cancer, HIV/AIDS, and neurological disorders. Such uses are prohibited by law; cannabinoid drugs are not registered for medical use in Australia and a smoked plant product is unlikely to be registered. A New South Wales Working Party has recommended granting exemption from prosecution to patients who are medically certified to have specified medical conditions. This proposal deserves to be considered by other State and Territory governments.

Wayne D Hall, Louisa J Degenhardt and David Currow

MJA 2001; 175: 39-40

In August 1999, the New South Wales Premier convened a Working Party on the Use of Cannabis for Medical Purposes¹ to advise on whether cannabis and cannabinoid drugs had any medical uses and, if so, to suggest how these substances could be made available for medical use without decriminalising cannabis for non-medical use. The Working Party's report was tabled in Parliament on 1 November 2000. Its recommendations were endorsed in principle by the Premier and are currently being considered by the NSW government. We believe that they deserve wider consideration.

The Working Party reviewed the scientific evidence on the safety and efficacy of the medical uses of the crude cannabis plant (which is usually smoked) and of cannabinoid drugs (pharmaceutically pure substances found in the cannabis plant, such as tetrahydrocannabinol [THC], or synthetic drugs that act on the same receptors in the brain as THC).² It agreed with the United States Institute of Medicine² and the UK House of Lords Standing Committee on Science and Technology³ that THC can be useful in treating nausea, vomiting and appetite loss in patients with HIV and in cancer patients undergoing chemotherapy.¹ It noted the suggestive evidence from animal studies and clinical case series that THC may relieve painful muscle spasms in neurological disorders and chronic pain that has not responded to conventional analgesics.² It recommended further research on the therapeutic use of cannabis and cannabinoid drugs in these conditions.

These recommendations do not address the needs of those currently using cannabis for medical purposes, as THC is not registered for medical use in Australia. THC is registered in the US, and a synthetic cannabinoid, nabilone, is registered in the United Kingdom to treat nausea caused by cancer chemotherapy and HIV-related wasting. These drugs could be registered in Australia if a pharmaceutical company applied. No company has done so to date.

Smoked cannabis can not be medically prescribed in Australia, as it does not satisfy the requirements for registration as a "therapeutic good" under the Therapeutic Goods Act 1989 (Cwth). Smoking is an unsafe and unreliable way to deliver a drug that may be used daily to treat a chronic illness.¹ The risks are much lower if cannabis is smoked for a limited time (eg, to treat nausea during a course of cancer chemotherapy, or to intermittently stimulate appetite in patients with HIV/AIDS or terminal cancer).¹

The best chance for establishing the medical use of cannabinoids lies in the development, testing and registration of new synthetic cannabinoid drugs. This is likely to take considerable time.² The next-best option is to find ways of administering THC that are more efficient than the oral route and do not involve smoking a crude cannabis plant product.² However, existing technologies (eg, transpulmonary delivery systems used for opioid drugs) are not readily adapted for delivering THC, which is not water soluble.⁴

In the meantime, under existing NSW law (and in other States/Territories except South Australia, the Australian Capital Territory and the Northern Territory), patients who smoke cannabis for medical reasons face criminal prosecution if detected by the police.

The Working Party's view was that the law should not compound the predicament of seriously ill patients. Accordingly, it recommended that a limited exemption from criminal prosecution should be given to specific classes of patients who wished to use cannabis for medical purposes. The exemption would be an interim measure until pharmaceutical cannabinoids were registered, and the effects of this exemption would be evaluated after a two-year trial period.

The exemption would be limited to patients who had been certified by an approved medical practitioner to have HIV-related or cancer-related wasting, nausea caused by cancer chemotherapy, muscle spasm in neurological disorders or spinal cord injury, or pain unrelieved by conventional analgesics.

Certification would have to be obtained before medical cannabis use. This would allow the practitioner to counsel the patient about alternative treatments and the risks of smoking cannabis, and to review their health regularly. The patient would have to renew the certificate after six months.

To allow patients to avoid resorting to the black market, the Working Party recommended that these patients be allowed to grow a small number of cannabis plants for their own use. In the case of seriously ill and debilitated patients, a carer would be allowed to grow the plants on behalf of the certified patient.

How many patients are likely to use such provisions? According to estimates derived from data supplied by the New South Wales Cancer Council, around 12 000 patients suffer from nausea during cancer chemotherapy or cancer-related wasting in any year.⁵ Another 2000 suffer from HIV-related wasting and neurological disorders and 4500 from chronic pain unrelieved by conventional treatments in New South Wales in any year. The total estimate of about 19 000 (Box) is likely to be an upper limit on the number of medical cannabis users, as the symptoms of many of these patients will be managed with existing treatments and others may not want to use cannabis.⁵

The size of the current cannabis black market makes it unlikely that cannabis grown for medical purposes will be diverted to the black market. The number of people who would be permitted under these recommendations to use cannabis for medical purposes is less than 2.5% of the 820 000 New South Wales adults estimated to have used cannabis for non-medical purposes in 1998.⁷

It is also unlikely that allowing exemptions for medical uses of cannabis will be seen as condoning the non-medical use of cannabis. In the US, survey evidence (and passage of citizen-initiated referenda)² show majority support for medical uses of cannabis, yet there is strong support for the continued prohibition of non-medical cannabis use.⁸

We believe that the Working Party's recommendations balance the needs of patients with community concern about non-medical cannabis use in a way that deserves to be considered by all State and Territory governments. Ultimately, patients with certain illnesses will be able to use pharmaceutical cannabinoids or other drugs, but, in the meantime, the Working Party's recommendations will allow these patients to use cannabis for medical reasons without changing the legal prohibition on non-medical use of cannabis, and without expanding the black market for cannabis products.

References

Report of the Working Party on the Use of Cannabis for Medical Purposes. Volume I: Executive summary; Volume II: Main report. Sydney: NSW Government, 2000. Available at <http://www.druginfo.nsw.gov.au/druginfo/reports/medical_cannabis.html>.
Institute of Medicine (United States). Marijuana and medicine: assessing the science base. Washington: National Academy Press, 1999.
House of Lords Select Committee on Science and Technology (United Kingdom). Cannabis: the scientific and medical evidence. London: The Stationery Office, 1998.
Mather L. Delivery systems for medical cannabis. Appendix D in the Report of the Working Party on the Use of Cannabis for Medical Purposes. Volume II: Main report. Sydney: NSW Government, 2000. Available at <http://www.druginfo.nsw.gov.au/druginfo/reports/medical_cannabis.html>.
Hall W, Degenhardt L. Estimated number of potential medical users of cannabis. Sydney: National Drug and Alcohol Research Centre, 2000. Available at <http://www.med.unsw.edu.au/ndarc/>.
Blyth FM, March LM, Brnabic AJM, et al. Chronic pain in Australia: a prevalence study. Pain 2001; 89: 127-134.
National Drug Strategy household survey: first results. Canberra: Australian Institute of Health and Welfare, 1999. (Drug Statistics Series; AIHW catalogue no. PHE 15.)
Johnston L, O'Malley P, Bachman J. National survey results on drug use from the monitoring the future study, 1975-1999. Rockville, MD: National Institute on Drug Abuse, 2000.

Authors' details

The National Drug and Alcohol Research Centre, University of New South Wales, Sydney, NSW.
Wayne D Hall, PhD, Executive Director, and Chair, Working Party on the Use of Cannabis for Medical Purposes;
Louisa J Degenhardt, BA(Hons), Research Assistant, and Research Officer, Working Party on the Use of Cannabis for Medical Purposes.

Flinders University, Adelaide, SA.
David Currow, MPH, FRACP, Professor of Palliative Care, and Member, Working Party on the Use of Cannabis for Medical Purposes.

Reprints: Dr W D Hall, The National Drug and Alcohol Research Centre, University of New South Wales, Sydney, NSW 2052.
w.hallATunsw.edu.au

©MJA 2001
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Estimated number of potential medical users of cannabis

It is difficult to estimate the potential number of people in New South Wales who suffer from conditions that might be alleviated by cannabis or cannibinoids for several reasons:

we are uncertain about the prevalence of these diseases;
we do not know what proportion of these patients have the symptoms which cannabis has been claimed to relieve; and
we do not know the proportion of these patients whose symptoms are unrelieved by existing treatments.

Cancer-related wasting: In 1997, 11 594 people died of cancer in NSW (NSW Central Cancer Registry, 2000). If we assume that almost all of these persons suffered from cancer-related wasting, then about 11 000 people might have benefited from cannabis use to improve appetite. This does not take into account people who experienced cancer-related wasting but who did not die.

Severe nausea from chemotherapy: Cancers vary in type, severity of symptoms and therapeutic regimen, so it is difficult to provide an accurate estimate of the number who may receive cancer chemotherapy that causes severe nausea and vomiting. Platinum-based chemotherapy is the most emetogenic form of chemotherapy, and is used in the treatment of ovarian cancer, testicular cancer, soft tissue sarcoma, 20% of head and neck cancers, 33% of distal oesophagus cancers, and about 10% of non-small-cell lung cancers. Based on 1997 estimates of these cancers, about 1000 people might have experienced severe nausea from platinum-based chemotherapy.

HIV-related wasting: According to the Australian Research Centre in Sex, Health and Society at La Trobe University (Vic.), there were 2289 people with clinical AIDS in 1999, and 55% of them lived in NSW. A survey of 924 AIDS patients conducted by La Trobe University suggested that a third of people with HIV/AIDS experience weight loss. If these figures are applied to the estimate in NSW, then there would be around 400 people with HIV/AIDS in NSW in any one year who would be potential medical consumers of cannabis or cannabinoids.

Muscle spasticity: According to the Multiple Sclerosis Society of Australia, patients with the disease known to the society represent 0.3% of the Australian adult population: about 11 000 people in NSW. To take account of patients not known to the society and to include people with less common neurological disorders whose symptoms may be alleviated by cannabis or cannabinoids (eg, patients with spinal cord injuries), we double this estimate, to 20 000. There are no Australian data on the prevalence of muscle spasticity among these patients. If we assume 10% prevalence, then about 2000 people with neurological conditions might benefit from cannabis or cannabinoids.

Chronic pain: In any year, 11% of males and 13.5% of females have chronic pain that interferes with daily activities.⁶ Of these, 2.9% will have seen a pain specialist and 20% of them will have incomplete pain relief (Dr F M Blyth, Pain Management and Reseach Centre, University of Sydney, personal communication). In NSW, this amounts to 4500 people.

Therefore, about 18 900 people in any year might benefit from the medical use of cannabis or cannabinoids. To this should be added the unknown number of persons with acute and chronic pain that is unrelieved by existing treatment.

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