Marijuana for medical purposes is on the rise in Australia, but we still know little about how it works – Health

Thousands of Australians are now using medical cannabis to treat diseases such as chronic pain and anorexia.

Yesterday, the ABC revealed that more than 3,100 scripts of medical cannabis had been approved by the Therapeutic Goods Administration (TGA) since the federal government eased the restrictions in March 2018.

According to experts, these people were only the visible part of the iceberg. There are an estimated 100,000 Australians who take drugs with cannabis that they illegally acquired.

The drug's lawyers say it offers a safe and effective solution to people with intractable medical problems.

Critics, and some of Australia's leading medical experts, claim that there is little evidence of quality supporting the use of cannabis for medical purposes in most cases.

So, what do we know about this? And why, in some cases, is it still so small?

The challenges of cannabis research

Research on the safety and effectiveness of cannabis has always been very difficult.

This is partly due to the illegal nature of cannabis and partly to the complexity of the cannabis plant itself.

Cannabis contains over 400 bioactive molecules, about 100 of which are cannabinoids – a diverse group of natural chemicals that bind to endocannabinoid receptors in the body to produce various effects.

The two main cannabinoids that have therapeutic effects are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD).

THC is known for its psychoactive effects – it's what makes a person "strong" and that's why people use marijuana for recreational purposes. CBD, on the other hand, is not psychoactive and is thought to moderate the "high" caused by THC.

The proportions of THC and CBD (and other cannabinoids) determine the choice of the product for the treatment of the disease.

Different cannabis strains contain different ratios of THC to CBD, and it is unclear whether they act individually or together.

Due to the inherent variability of the cannabis plant, as well as the many ways it can be administered, the types of products, doses, and research methods used in clinical studies have varied considerably.

According to the TGA, this has made it difficult to "make definitive conclusions" about the best use of cannabis for therapeutic purposes.

This is also why, with the exception of a product (used for muscle spasticity in multiple sclerosis), cannabis-based medications are not available as prescription medications registered .

What the evidence says

Despite the suggestions, medical cannabis can help everything from chronic pain to anxiety reduction, the scientific literature to date has painted a contrasting and largely inconclusive picture.

While the public has become more and more interested in drugs in recent years, the National Center for Drug and Alcohol Research (NDARC) conducted a systematic review in 2017 of cannabis for medical use. , which is the basis of current TGA guidelines.

Overall, the review concluded that the evidence was "limited" and suggested that cannabis should only be used when registered drugs had "been unsuccessful".

Jennifer Martin, director of the Australian Center for Clinical Excellence and Cannabinoid Research, said it was best for patients to use drugs previously saved by the TGA.

"It's because the current therapies we have have been evaluated in terms of safety, quality and consistency," said Professor Martin.

The review of the TGA revealed that the strongest evidence of medical cannabis was in children and young adults with drug-resistant epilepsy, for which CBD products have been shown to reduce the frequency of seizures by 50% or more in almost half of pediatric patients.

"It's probably where our best evidence is to date," said Professor Martin.

The review found "weak to moderate" evidence that cannabis medications could help painful symptoms of multiple sclerosis, although the evidence was inconsistent.

For nausea and vomiting induced by chemotherapy, the review found that medicinal cannabis products with a high THC content were "as effective" as conventional drugs – but only compared marijuana with older and replaced drugs.

"Most of the studies were on the 1990s, before we had very good drugs for nausea and vomiting induced by chemotherapy," said Professor Martin.

For chronic painIt seems that medicated cannabis can relieve neuropathic (nerve) pain – but for most patients the effect was modest.

However, a large-scale study conducted in 2017 by the National Academy of Sciences, Engineering and Medicine in the United States revealed "substantial evidence that cannabis is an effective treatment for chronic pain in adults."

"But when the Australian team updated the information, she discovered that we would have to treat 24 patients with this particular cannabinoid so that one of them would get a reduction in their symptoms painful, "said Professor Martin.

Professor Martin said that although cannabis for medical use might be less harmful than opioid drugs, the solution to chronic pain was not so much simply by moving a drug away from a pain medication. to another.

"It's an important issue that requires further research … but I think my peers in the world of pain medicine and addiction will tell you that it's not that simple," he says. she said.

When it comes to palliative care, the NDARC review revealed that there is little evidence that medical cannabis benefits advanced cancer patients with chronic pain.

However, Michael Farrell, director of NDARC and contributing editor of the 2017 review, said the main concerns about medical cannabis were centered on long-term consumption – which "is not a problem" at the end of life .

"I do not see why we should worry too much about complex evidence if it's about short-term management," said Professor Farrell.

Taking a cautious approach

Iain McGregor of the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney said that although more research is needed on medical cannabis, it was important not to confuse "insufficient evidence" with "lack of evidence. "

"In many cases, the TGA guidelines indicate that quality evidence has not been collected in a particular area," said Professor McGregor.

"The result is very different from that of good quality studies and cannabis was ineffective.

Professor McGregor said that he thought that Australia "was taking an overly cautious approach" to medicinal cannabis.

"I think other similar OECD countries have decided to give the benefit of the doubt to cannabis, especially in desperate patients," he said.

But Professor Martin said Australia was right to take a slow and steady approach to learning about the efficacy and safety of medical cannabis.

"Patients have a short-term solution: they can access the TGA system," she said.

"But in the long run, we still need to collect rigorous data and make sure our patients are safe before deploying open access to a product that we do not really know how to use properly."

Professor Farrell agreed and stated that it was "important that people have realistic expectations as to what medical cannabis could do, other than to think that it is some sort of quick fix".