Potential health effects of higher potency (Australian Category 5) medicinal cannabis products

Investigators: Myfanwy Graham, Dereje Assefa, Dr Paul Kellner, Dr Cong Ngo, Diki Tsering, Veronica Delafosse, Prof Suzanne Nielsen

Funder: Therapeutic Goods Administration; Department of Health, Disability and Ageing

This project focused on Category 5 medicinal cannabis products, which are characterised by their high delta-9-tetrahydrocannabinol (THC) >98% and minimal cannabidiol (CBD) content. We conducted a rapid review of studies involving products consistent with Category 5 product composition in Australia to understand the potential health effects, including the efficacy and safety, of these cannabis products in adults. The upper limit of THC concentration in the retrieved RCTs and observational studies was 22.6% (range 16-22.6%), with no studies identified that considered THC concentrations higher than these.

Overall, the rapid review found a small number of RCTs and observational studies that contribute insights into the potential efficacy and safety of products with THC concentration of up to 22.6% in a limited range of physical and mental health conditions.

A critical evidence gap is the lack of any research into the potential efficacy and safety considerations related to products with THC concentrations greater than 22.6%, which appear to be increasingly commonly prescribed in Australia.

This project was a collaboration between Monash Addiction Research Centre and BehaviourWorks