Stats show there has been a fairly slow uptake of medical cannabis to treat nausea and vomiting caused by chemotherapy, possibly because of a lack of good evidence.

Recent legislation allows the prescription of medicinal cannabis by medical practitioners in Australia for the prevention and management of chemotherapy-induced nausea and vomiting.

However, the most recent evidence-based guidelines for the prevention and management of CINV authored by leading global and Australian bodies provide limited support for use of medicinal cannabis.

As of July 2018, only 34 Australian doctors have taken up the offer to become registered prescribers of medicinal cannabis.

The current situation illustrates “the challenges of managing community demand for access to such products, and highlight the importance of conducting appropriately designed clinical trials”, according to Dr Antony Mersiades, who is a Clinical Trials Fellow at the University of Sydney’s NHMRC Clinical Trials Centre.

Previous trials of cannabinoid products containing tetrahydrocannabidiol (THC), cannabidiol (CBD) or synthetic derivatives have been compromised by small sample sizes and outdated control arms, Mersiades and colleagues wrote.

One in particular was reported to show “a promising efficacy signal and tolerable psychological adverse event profile” despite the fact that one of the seven patients who received the active drug withdrew due to “transient psychotic symptoms”, experts say.

“The Therapeutics Goods Administration guidance documents conclude that use of medicinal cannabis for CINV is experimental, and should only be considered for the management of intractable symptoms where standard therapies are ineffective,” they wrote.

A clinical trial is currently underway in New South Wales to determine the efficacy, safety and cost-effectiveness of using medicinal cannabis to prevent chemotherapy-induced nausea and vomiting.

The Cannabis CINV trial in NSW has recruited over 60 of 80 planned participants for a new phase 2 trial, with expansion to a 250-participant phase 3 trial planned if phase 2 results are encouraging.

“The results of such clinical trials will provide guidance to clinicians regarding appropriate use in specific indications, product selection, dosage and titration, and appropriate monitoring of both efficacy and safety,” Dr Mersiades said.