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Framing the use of cannabis as a medicine in New Zealand: Regulatory, Clinician and Patient contexts

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thesis
posted on 23.05.2021, 21:30 by Karen Oldfield

A medicine is a substance developed for administration to humans for therapeutic purposes that achieves its action by pharmacological, immunological or metabolic means. Pharmaceutical medications undergo years of pre-clinical and clinical trials to establish their safety, tolerability and efficacy. Cannabis, whether in raw or processed form, sits predominantly outside this remit. Its use falls broadly into four categories; recreational, plant used for medicinal purposes, cannabis-based products marketed for medical purposes and pharmaceutical grade cannabinoid medications. The use of cannabis as a medicine involves complex interactions across social, health and political domains, at both a global and national level. New Zealand has attempted to address this with the implementation of the Medicinal Cannabis Scheme in April 2020.

This research was undertaken to develop an understanding of what effect cannabis regulations have had on multiple jurisdictions enacting them and applying this to the New Zealand context, and to understand specific groups of patient-doctor interactions regarding the use of cannabis as a medicine.

First, I undertook a meta-narrative qualitative review synthesising themes relating to the outcomes of cannabis regulatory change across multiple jurisdictions. Five super-ordinate themes were identified in the meta-narrative review; Normalisation, Gatekeeping, Economics, Community and Health, which were applied in framing the conclusion of this thesis.

I then completed a systematic review / meta-analysis examining label accuracy and contaminants in cannabis-based products in regulated markets. Labelling accuracy ranged from 17 to ~86%. Contaminants included microbes, solvents, pesticides and adulterants. Meta-analysis of pesticide contamination showed that the overall proportion of contaminated samples was 0.25 (95% CI: 0.10 to 0.40, Heterogeneity: I2=79%, X12=4.74, p=0.03).

Finally, I completed six observational studies within New Zealand to determine knowledge, beliefs and reported interactions of doctors and patients regarding the use of cannabis as a medicine in three medical disciplines; general practice (GP), oncology and neurology.

Doctors reported that patients were requesting medical cannabis prescriptions (GP: 55%, Neurology: 63%. Oncology: 84% respectively), and informing them of using illicit cannabis for medical symptoms. All doctors were concerned about prescribing cannabis as a medicine due to lack of evidence and lack of understanding of the prescription processes. Despite this, the majority were willing to prescribe a funded cannabis-based product backed by evidence of efficacy in traditional clinical trials.

Patients in all three disciplines indicated comfort discussing cannabis with GPs and specialists (GP patients: 91.7%, 92.1%, neurology patients: 88.2%, 90.6%, oncology patients: 85.8%, 88.2% respectively). All groups reported low levels of prescriptions received (<20%). Patients reported illicit use of cannabis for medical reasons (11.2%, 34.6% and 35.5% in GP, neurology and oncology patients respectively), with reported effectiveness of illicit cannabis for their condition ranging from 86.7 to 94.0%. Patients in all three fields wished to know the benefits, side effects and availability of cannabis-based products and had concerns regarding access and cost.

The use of cannabis as a medicine remains a complex situation within the NZ context. Significant implementation issues remain for the Medicinal Cannabis Scheme to ensure the safety and wellbeing of patients in New Zealand.

History

Advisor 1

Braithwaite, Irene

Advisor 2

Beasley, Richard

Copyright Date

21/05/2021

Date of Award

21/05/2021

Publisher

Victoria University of Wellington - Te Herenga Waka

Rights License

Author Retains Copyright

Degree Discipline

Clinical Research

Degree Grantor

Victoria University of Wellington - Te Herenga Waka

Degree Level

Doctoral

Degree Name

Doctor of Philosophy

ANZSRC Type Of Activity code

School of Biological Sciences

Victoria University of Wellington Item Type

Awarded Doctoral Thesis

Language

en_NZ

Victoria University of Wellington School

School of Biological Sciences