Health update: medical marijuana
Should we legalise cannabis for medical use? Professor Kerryn Phelps reports on controversial new clinical trials that are starting in Australia.
BACK IN 1996, I was working as the medical reporter for the Today show on the Nine Network in Australia. I travelled with a production crew to San Francisco to investigate the move in California to legalise cannabis for medical use. This new law enabled legal access to cannabis for people with cancer, AIDS, multiple sclerosis and some other medical conditions, provided that they had a doctor’s recommendation.
Canada, Switzerland, the Netherlands and Israel have legalised programmes for medical cannabis. Conversely, cannabis is treated as a serious illicit drug in other countries, such as Indonesia, with a conviction for importing large quantities attracting the death penalty.
In New Zealand, cannabis-based products can be prescribed for medical use subject to ministerial approval. The only pharmaceutical-grade cannabisbased product currently available in New Zealand is Sativex, which is approved for use in multiple sclerosis. It may also be prescribed for ‘off-label’ uses for conditions such as chronic pain, neuropathic pain, cancer pain and intractable childhood epilepsy.
There are no clinical trials of cannabis-based products being conducted in New Zealand at present, however the first clinical trials in Australia have begun in New South Wales, with the federal Parliament passing laws earlier this year to legalise the growing of cannabis for medicinal products. The trials aim to determine conditions where it might be useful, the best method of delivery, dose to be used and side-effects.
Under the Single Convention on Narcotic Drugs 1961, the commercial cultivation of cannabis in New
Zealand for medicinal purposes is not allowed except under the control of a government agency, which has to purchase the crop after harvest. Such an agency does not currently exist in New Zealand.
HOW CANNABIS IS USED
The most common ways for cannabis to be used are by inhalation of smoke or vapour, in food, tea, capsules or a sublingual spray. Smoking it can cause damage to your lungs and airways, and cause inflammation in your nose, throat and sinuses. In countries with medical cannabis programmes, inhalation is recommended via a specific type of medical vaporiser.
IS IT EFFECTIVE?
The principal reason for medicinal cannabis trials is to establish effectiveness in specific medical conditions where the options for medical treatments are limited, such as intractable childhood epilepsy.
There is evidence for cannabis being effective in treating a number of difficult conditions including:
Cancer-related nausea, loss of appetite, weight loss and debilitation.
Nausea and vomiting related to chemotherapy.
Some forms of chronic pain, including nerve pain.
Muscle spasms of multiple sclerosis. Cannabis will not cure the underlying problem, but may help manage symptoms and reduce reliance on other pharmaceutical medication.
I expect once a medicinal cannabis programme is running, doctors will only recommend it where standard medical treatments are not giving adequate relief or are likely to cause unacceptable side-effects.
Different types of cannabis have different effects and side-effects. Be clear about why you are considering cannabis. Could your symptoms have a legal, safe and effective remedy?
The aim is to use small doses to the point of symptom relief. Higher doses will achieve a ‘high’, but this is more likely to cause unwanted side-effects.
If you have any medical condition affecting your lungs or breathing capacity, smoking tobacco or cannabis can make it worse.
Do not use cannabis in any form if you are pregnant or planning a pregnancy, as it can damage a foetus and may increase the risk of some future childhood cancers. The active ingredient also crosses into breast milk so cannabis use is contraindicated while you are breastfeeding.
If you have a family history of schizophrenia or other psychotic illness, cannabis is best avoided.
If you have a history of heart disease, you need to be cautious because the adverse effects of cannabis on heart disease are not known.
Because cannabis is addictive, if you use it at high doses regularly, physical dependence is a possibility and if you stop using it, you can experience a withdrawal syndrome including several days of irritability, restlessness, sleeping problems, nausea and hot flushes.