Published: 23 March 2022

It is strongly recommended that the linked article is read before considering the questions.

• An overview of medicinal cannabis for health practitioners

As of 1 April, 2020, regulatory changes came into effect to make medicinal cannabis more accessible to patients in primary care in New Zealand. Registered medical practitioners (i.e. doctors) can now prescribe medicinal cannabis via two main pathways:

1. Products that have consent for distribution (approved or provisionally approved) under the Medicines Act 1981, e.g. Sativex
2. Products that are not approved, but that are verified by the Medicinal Cannabis Agency as meeting minimum quality standards

For an up to date list of available medicinal cannabis products, see: https://www.health.govt.nz

If a medicinal cannabis product does not fit the criteria of being a cannabidiol (CBD) product^* then it is considered to be a controlled drug, and therefore subject to corresponding restrictions. There are pathways for doctors to prescribe medicinal cannabis products that are neither Medsafe approved nor verified by the Medicinal Cannabis Agency as meeting the minimum quality standard – such products need to be imported directly from overseas either by the prescribing doctor, or by a registered pharmacist on their behalf.

^* A CBD product is a type of medicinal cannabis product where (1) CBD is present and constitutes at least 98% of total cannabinoid content, (2) the tetrahydrocannabinol [THC] and other specified substance content do not exceed 2% of the total THC, CBD and other specified substance content, and (3) no other controlled drugs or psychoactive substances present. For further information, see Section 2A of the Misuse of Drugs Act 1975.

For any product that does not have Medsafe approval or provisional approval, it is important to recognise that it lacks an endorsement of meeting New Zealand’s official efficacy and safety standards; this process requires the submission and review of robust pharmacological data and human clinical trial results. Unless a medicinal cannabis product obtains Medsafe approval, prescribers are the ‘gate-keepers’ to access for patients and must take responsibility for any outcome associated with prescribing an unapproved product. Therefore, it is important that healthcare providers familiarise themselves with information regarding medicinal cannabis to help navigate discussions with patients, and to ensure that informed clinical decisions are made.

Despite numerous anecdotal reports from people claiming that medicinal cannabis products are effective, the available pool of peer-reviewed clinical trials in humans is limited, and the quality of evidence is not considered to be strong. Therefore, medicinal cannabis products cannot currently be considered a first-line option for any indication. However, trialling a medicinal cannabis product may be suitable in some cases if (1) patients experience ongoing symptoms despite optimal dosing of available evidence-based treatments, or (2) conventional treatments are contraindicated or not tolerated. This shared decision should be informed by a discussion balancing the potential benefits of treatment against possible adverse effects and patient-specific risk factors. Potential indications for which medicinal cannabis could be considered include chronic neuropathic or malignant pain, chemotherapy-related nausea and vomiting, refractory spasticity associated with multiple sclerosis and seizures due to epilepsy.

Transient and mild adverse effects commonly occur when initiating use of a medicinal cannabis product, which may be tolerable if anticipated. However, more severe adverse effects may occur in some patients, e.g. acute psychosis, particularly with THC-dominant formulations. Medicinal cannabis is generally not appropriate during pregnancy, in patients with a personal or family history of psychiatric disorders, unstable cardiovascular or cardiopulmonary disease or a history of hypersensitivity to any component used in manufacturing. Caution is also advised when considering medicinal cannabis in some other patient groups, including those with hepatic or renal impairment, a history of falls, previous risk-associated behaviours, or those who lack psychosocial support.

If a decision is made to prescribe medicinal cannabis, a treatment plan should be established to assess the product's effectiveness and safety. An initial one-month period is likely suitable to establish whether there is a clear benefit based on an agreed treatment objective, e.g. a metric improvement in a pain score or symptom algorithm (e.g. 30%) or an objectively measured goal such as being able to perform a daily task that they were previously unable to. Any benefit can in turn be balanced against adverse effects that occur, the risk of which can be reduced by starting at a low dose and gradually titrating upwards. Use of the medicinal cannabis product should stop if the desired effect is not obtained after 4 – 12 weeks, with risk management and discontinuation strategies established as appropriate.

Questions for discussion:

1. Has reading this resource improved your understanding of the new regulatory framework for prescribing medicinal cannabis? How challenging (or straightforward) do you consider the process of prescribing medicinal cannabis to be?
2. The efficacy and safety of medicinal cannabis has been investigated in clinical trials across a range of indications, however, there are ongoing discussions in the medical community regarding the quality of evidence. Do you have confidence in the existing studies that support the efficacy of medicinal cannabis?
3. Have you ever prescribed medicinal cannabis?
   • If so, what did you prescribe it for and was the patient receptive to considering conventional evidence-based treatments first? What was the outcome?
   • If not, would you consider prescribing it? And for what indications or clinical scenarios?
4. Are there particular red flags in the patient’s history that might influence your decision to prescribe medicinal cannabis?
5. Given the potential psychoactive effects associated with both CBD- and THC-containing medicinal cannabis products and risk of intoxication with THC consumption, certain activities may need to be avoided while it is being used. What recommendations would you give to someone regarding medicinal cannabis and driving or operating heavy machinery, and would the THC:CBD ratio influence this?
6. A treatment plan is strongly recommended for any patient prescribed medicinal cannabis. How do you go about putting this plan in place? What are some of the main issues you may encounter and how do you manage these situations? e.g. patients wanting to continue use despite not achieving an objectively measured goal of treatment, potential evidence of misuse.