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Clocktower. Friday 3 May 2019 10:39am

Following the Government's move to increase access to medicinal cannabis, two University of Otago scientists are cautioning that in any future changes cannabis products should be held to the same standards as other medicines.

Michelle Glass image
Professor Michelle Glass

In the latest issue of the New Zealand Medical Journal out today, Professor Michelle Glass and Associate Professor John Ashton from the Department of Pharmacology and Toxicology outline some potential issues in determining the regulations for a Medicinal Cannabis Scheme.

“We argue that what is considered a medicine in the legal and pharmaceutical sense should not be changed in an ad hoc way to accommodate cannabis, but that cannabis products should be held to the same standards as other medicines,” the opinion article by the pair states.

Professor Glass explains they decided to publicly air their views to ensure the science does not get lost in what is becoming an increasingly public debate.

“New Zealand has a clear framework which defines the standards required for something to be considered a medicine, yet appears on the cusp of creating a whole new class of 'medicine' to accommodate medicinal cannabis,” Professor Glass says.

In December last year, the Government introduced the Misuse of Drugs (Medicinal Cannabis) Amendment Act and it now has until December this year to determine the regulations for a Medicinal Cannabis Scheme.

The academics state in the article that public surveys indicate widespread support for increased access to medicinal cannabis, yet GPs and clinicians generally remain more reserved.

“We believe that part of this difference lies in the lack of clear public understanding of the term 'medicinal cannabis' and a relatively greater awareness by health professions of what generally constitutes a medicine.

“Current media use of the term 'medicinal cannabis' encompasses everything from pharmaceutical grade plant-derived medicines, such as Sativex, through to home-grown raw plant materials. From the perspective of a potential prescriber these are very different products.”

The pair highlight that one of the first problems in considering cannabis as a medicine is that it is not a single entity, but a diverse range of related substances and products all referred to as “cannabis” in popular usage.

John Ashton image
Associate Professor John Ashton

Associate Professor Ashton says regulatory approval of medicines requires exact composition to be known and be able to be replicated for batch-to-batch conformity.

“It requires detailed stability data and to ensure that products are free from contaminants. Clinical efficacy must be proven and adverse effects monitored.

“If we are going to ask doctors to prescribe cannabis as a medicine, why would cannabis products not be required to meet existing standards?” he questions.

In the NZMJ article, they argue that even if various cannabis products might have benefit for some patients, it is not helpful to classify anything other than a pharmaceutical grade product as a medicine.

“The quality control rigors for classification as a medicine, the properties that a substance must have for safe and effective prescribing, the assessment and monitoring of effects – both therapeutic and adverse – are safeguards that should not be compromised or redefined without a careful consideration of the consequences, many of which could be unintended.”

Background information about the authors:

Professor Michelle Glass
Read an article on Professor Glass's research into synthetic cannibis

Associate Professor John Ashton
View Associate Professor Ashton's profile on the Department of Pharmacology and Toxicology website
View Associate Professor Ashton's profile on the Brain Health Research Centre's website

For further information, contact:

Professor Michelle Glass
Head of Department of Pharmacology and Toxicology

Associate Professor John Ashton
Department of Pharmacology and Toxicology
Tel +64 3 479 3040

Liane Topham-Kindley
Senior Communications Adviser
Tel +64 3 479 9065
Mob +64 21 279 9065

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