Australians still waiting for grass to grow for medicinal cannabis use

Australia is likely to see the decriminalisation and retail of cannabis well before its widespread medical use.

Since it was downscheduled in 2016 by the Therapeutic Goods Administration to allow it to be prescribed by any doctor in Australia, its uptake as medicine has been limited. That is disappointing since the anti-inflammatory and psychotropic effects of cannabis — and the ubiquity of inflammation and stress as determinants of disease — make it a potentially useful drug for many common health conditions. 

The major cannabinoids (active ingredients) of the cannabis flower are cannabidiol (CBD) and tetrahydrocannabinol (THC). When consumed by humans, THC and CBD activate cannabinoid receptors CB1 and CB2 — these propagate and modify activity in the central nervous system, the immune and other organ systems. Any molecule, not exclusive to the cannabis plant, that activates these receptors can be described as a cannabinoid — they can be found in other familiar products like black pepper and chocolate.

But why do we have these receptors? Since there’s no evolutionary advantage in having a dedicated system to tell us we’ve eaten chocolate, the theory of endogenous cannabinoids was developed. The idea is that we have an equal and opposite hardwired system to counter the fight-or-flight response — a mechanism to tell us we are safe, satiated and it’s time to chill out. The discovery in 1992 of anandamide, a cannabinoid produced in the human body, added weight to this theory.

While the pharmacology of cannabis is well known, and there is ample in vitro (what happens on a petri dish) evidence to spruik it as the next naturally occurring medical miracle, there is limited in vivo (what happens in real life when you administer it to a bunch of people) evidence for its real-world effects.

The high quality evidence we have for cannabis has been summarised by the Royal Australian College of Physicians, concluding good evidence to suggest that it:

• Reduces chronic pain in adults

• Is an effective anti-nausea agent

• Reduces muscle spasticity in multiple sclerosis.

Beyond these indications the medical use of cannabis is entirely speculative, relying on low quality evidence.

So why is a prehistoric plant like cannabis so hard to research and integrate into Western medicine? Especially when aspirin is derived from tree bark, morphine comes from a flower and penicillin happened on a bit of cheese.

Part of the reason is a lack of incentive for the private sector to research and develop cannabis products. CBD and THC are well known, naturally occurring and so can’t be patented for profit.

Sociopolitically, cannabis is loaded with centuries of baggage as an illicit drug of varying acceptability according to whichever coloniser or religion was in charge at the time. Its current status in Australia is coloured by America’s war on drugs (though ironically cannabis is now available for recreational use in more than 20 US states while, at the federal level, the country remains on a war footing with the plant).

Australia seems to be on the same trajectory traced by the US and Canada — a period of speculative medical use proved wildly popular and, through mass uptake, provided the gateway to legal recreational use. 

If Australia does follow North America then cannabis’ status as a medicine, the evidence for and against it, is redundant as it will simply become another item on the plant-based shopping list. In that case we need only one piece of evidence that has been very clearly established: cannabis causes harm at a far lower rate than alcohol and tobacco. 

Have you or someone you know used medicinal cannabis? Was there a problem getting it? Let us know by writing to letters@crikey.com.au. Please include your full name to be considered for publication. We reserve the right to edit for length and clarity.