Justin Sinclair and Mike Armour – medicinal cannabis

ENZ is committed to facilitating and supporting research to develop a greater understanding of health issues, particularly relating to endometriosis. We support research directed by other organisations, as it’s important to have published literature to improve health outcomes for those with endometriosis.

What is medicinal cannabis? 

Medicinal cannabis is a legal medicine now in New Zealand, and is best defined as cannabis that is not only prescribed and supervised by a medical doctor, but has also undergone extensive analytical testing to ensure that it is safe and of high quality, meeting the strict standards of the NZ Regulator. This includes tests that ensure cannabinoids (the main active constituents in cannabis, such as delta-9-tetrahydrocannabinol [THC] and cannabidiol [CBD]) are standardised and within limits, and also that the medicine, whether that be as dried flower or an oral oil, is tested for things such as solvent residues, microbial contamination (e.g., bacteria, mould), heavy metals and other unwanted nasties such as pesticide residues. Only products that meet these high-quality standards, and are prescribed by a doctor, are what fit the classification of medicinal cannabis.

What is the difference between medicinal cannabis and illicit cannabis?

Great question – and one we get frequently. The simple answer is that medicinal cannabis is prescribed by a doctor and meets strict quality assurance standards, and that illicit cannabis doesn’t. Whilst many participants across our surveys and focus groups have utilised illicit cannabis for therapeutic purposes to manage the pain and associated symptoms of their endometriosis, the reality is that you do not know what is in the cannabis you are using, and the people you may be procuring it from likely won’t either. It costs thousands of dollars to run the battery of tests to produce a certificate of analysis to ensure the safety and quality of finished medicinal cannabis material. These standards for testing have been established by the New Zealand Regulator to protect patients from potential adulterated or contaminated products.

Another difference may be the differences in chemovars used between illicit and medicinal cannabis. Chemovar is just a fancy name to denote the different chemical varieties of cannabis…these varieties may look and smell different, and also have diverse chemical compositions, but they still all belong to the Cannabis genus. Over the last 40 years, illicit cannabis has been largely bred to be high in THC, the main intoxicating cannabinoid, and devoid of most other cannabinoids. Whilst medicinal cannabis products can also be high in THC, they tend to have other cannabinoids present and are generally lower in THC potency than may be found in illicit supply chains.

Is medicinal cannabis safe?

Like all medicines, medicinal cannabis also has some side-effects and adverse effects that can occur in some people, but overall, as it is prescribed and supervised by a medical doctor and the products being used comply with high quality standards, many of these can be minimised or avoided. Some of the common side-effects associated with medicinal cannabis include dizziness, fatigue, dry mouth, cognitive effects and anxiety. More rare adverse effects include depression, psychosis, tachycardia (fast heart rate) and poor coordination. If people are using medicinal cannabis, it should be noted that if you are prescribed products that contain THC, then caution needs to be observed if you are driving or using any heavy machinery, but your doctor or pharmacist will be able to provide more information on this.

Is medicinal cannabis legal in New Zealand? 

Yes. The Medicinal Cannabis Scheme came into effect across New Zealand on the 1st of April, 2020. The purpose of this scheme was to improve patient access to quality-assured medicinal cannabis products which can be prescribed by medical doctors around the country.

What are the risks involved with medicinal cannabis use?

Medicinal cannabis does have some risks. As research is lacking in certain areas, it is not advised to take medicinal cannabis if you are pregnant, seeking to become pregnant, or breastfeeding, as the impact this may have on the developing child is an unknown at this point and could pose a risk. Additionally, if you have a history of schizophrenia, or other serious mental health conditions, it is important that you discuss this with your doctor before commencing treatment so they can assess any risks.

Lastly, as mentioned previously, if you need to drive or operate heavy machinery, or work in industries where you are drug tested for work, then medicinal cannabis can potentially impact these activities and how safely you can both operate vehicles/machinery, or perform your duties. Once again, speaking with your doctor about these matters before you start using medicinal cannabis is strongly advised as it carries certain risks, both to your own safety, and the safety of others.

How could medicinal cannabis help treat endometriosis symptoms?

Cannabinoids such as THC and CBD show many different pharmacological actions in the scientific literature. These include anti-inflammatory, antioxidant, analgesic (i.e., pain relieving), neuroprotective, anti-emetic, appetite stimulant, immunomodulatory and muscle relaxant actions. THC, the constituent commonly associated with being high or stoned (i.e., intoxicated) has also demonstrated hypnotic (sleep-inducing) activity, which many people with endometriosis also experience as a symptom, whereas CBD has known anxiolytic (i.e., reducing anxiety) and anti-depressant activities, which are both commonly experienced by those with endometriosis and chronic illness more broadly.

Research is also starting to suggest that the endocannabinoid system, a neuromodulatory system in the body which regulates many homeostatic mechanisms, may be impacted in those with endometriosis, but more research is needed to fully understand this relationship.

What are the potential benefits of medicinal cannabis for endometriosis sufferers?

Our previous research has shown that people with endometriosis report benefits for their pelvic pain and gastrointestinal symptoms (like bloating or ‘endo belly’), improvements in their sleep and reductions in anxiety when using cannabis. Even more important is the fact that people consistently report a ‘substitution effect’, this is where people report reductions in their pharmaceutical or other medications that they normally use to manage their endometriosis symptoms. People with endometriosis have told us they have significant reductions in their use of pain killers, either over the counter pain medications like ibuprofen and Panadol, or prescription opioid painkillers like tramadol or endone, as well as other medications often used such as benzodiazepines (which includes drugs like diazepam) and neuroleptics (which includes gabapentin and lyrica). Since some of these medications like opioids do have concerns around dependence and addiction, reducing or eliminating these may be beneficial to people.

At present the research is mostly on self-reported changes in symptoms and we currently don’t have any high-quality evidence from prospective studies or clinical trials, so it’s hard to say how much of this benefit is from using cannabis (either medicinal or illicit) and how much may be due to what we called non-specific effects, which is things like expectation – where you expect to feel better after taking something. While the self-reported evidence is compelling, we need to do more high-quality studies to better understand the potential benefits, if any, of using medicinal cannabis for endometriosis.

What do New Zealanders involved in your research studies think about medical cannabis use to treat their endometriosis pain? 

We published a paper with leading New Zealand academics in the Journal of Womens Health that focused on illicit cannabis use as a management strategy for New Zealanders with endometriosis. Survey participants self-reported that it assists with their endometriosis pain, and that 95% were utilising cannabis to improve both pain and sleep. This is quite remarkable when you consider it is illicit cannabis and not standardised or quality-assured medicinal cannabis that was being utilised by this cohort.

We are also excited to let you know that we have just submitted our focus group research, which involved both Australian and New Zealand participants, to a journal for peer-review. In this qualitative research project, we found that 73% of the combined cohort were using cannabis for their pain and symptoms of endometriosis, and that many were able to stop or significantly reduce some of their pharmaceutical medicines (See Question 12 for more information on this). The majority of participants across both Australia and New Zealand were positively disposed to try medicinal cannabis as a management option as many suggested that current medical options, whether pharmaceutical or surgical, were not giving them effective relief. Conversely, many participants cited that current drug driving laws, workplace drug testing policies, the impact of stigma across employment, cultural, religious and social domains and the judgement of medical professionals, were significant barriers to adoption and utilisation of this now legal medicine.

On that note, a big thank you to all of the kiwi endo warriors for participating in our research projects over the last few years, as it is your voices that are integral to us understanding how this newly legalised medicine works, and the challenges you are facing accessing it. All of this information will assist us co-designing effective clinical trials which will provide the evidence we urgently need so that doctors can prescribe with more confidence and education.

How much research is there to support medicinal cannabis’ effectiveness on pain management for endometriosis sufferers? 

Very little unfortunately, as most of the research we have conducted thus far has been on the illicit use of cannabis for therapeutic purposes, but we are working hard to try and rectify this. We did publish a journal article in PLOS One that investigated the effects of cannabis ingestion on endometriosis-associated pelvic pain and related symptoms. This was a retrospective archival data analysis of the Canadian Strainprint app, which allows people to track medicinal cannabis usage, including the dosage form, dosage and changes in symptoms over time for a number of different clinical indications. Findings from this paper showed that quality-assured medicinal cannabis does appear to be effective for pelvic pain, particularly via the inhaled / vaporised route of delivery, and that this is likely due to the fast onset of pharmacological activity. Conversely, oral oils were reported as being superior for the less reported mood and gastrointestinal symptoms categories.

We are conducting a clinical trial of two different quality-assured medicinal cannabis products and standard care versus standard care alone very soon, and we hope to start recruiting for that trial in Australia early 2023.

Were there any unexpected findings in your studies on medical cannabis to treat endometriosis pain? 

We had some interesting findings in the PLOS One paper we talked about above, where subject perceived effectiveness of medicinal cannabis, across a variety or symptoms and dosage forms, appeared to increase with greater age. Why this is we don’t quite know, but it could plausibly be due to age related change to organ function, changing hormone levels, decline in endocannabinoid system functioning or that pain perception may change over time in those with endometriosis.

In our Journal of Women’s Health article specific to New Zealand, a very interesting finding was that cannabis use for endometriosis pain and related symptoms caused what is known as the Substitution effect, whereby participants reported stopping or significantly reducing their pharmaceutical medicines when using cannabis. 80% reported that cannabis has reduced their normal medication usage, with 59% able to completely stop a medication, with opioids being the most common class of analgesic stopped. Considering the addiction and side effect potential of opioids, this is quite a substantive finding.

Whilst this reduction in medication use was interesting, another paper we published this year (2022) in the Journal Cannabis and Cannabinoid Research, which surveyed New Zealanders and Australians, showed that only 23% of Australians and 6% of New Zealanders were utilising medicinal cannabis from a doctor, with the majority still utilising illicit supply for therapeutic purposes. More concerning was that a substantial proportion of this cohort (Australian-18.8% and New Zealand-23.5%) reported they had not disclosed their cannabis use to their doctor and were not going to, citing concerns over legal repercussions, societal judgement and their doctors presumed unwillingness to prescribe legal medicinal cannabis to them. Whilst not unexpected due to the impact stigma has across many levels of society for this now legal medicine, the concern we have is that cannabis can change the way certain medications work, or interact with certain medications, and so discussing this with your doctor or pharmacist is really important. Additionally, certain pharmaceutical medications like antidepressants, opioids and benzodiazepines should not be stopped abruptly as they can cause significant side-effects, and so once again, this really does need to be discussed with your doctor so that your safety and wellbeing are prioritised.

What does the future look like for medicinal cannabis use to treat endometriosis pain?

It is hopeful that instead of a ‘one size fits all’ approach there will be multiple approved medicinal cannabis products available for those with endometriosis based on their symptoms, preferences and needs. Inhaled cannabis and oral oils have different speeds of onset and duration of action so can be used for different things. Inhaled cannabis via a vapouriser usually acts quickly, having an effect within 5-10 minutes but usually only lasts a couple of hours at most, while an oral oil can take 90 minutes to have an effect but can last 5-6 hours. So for some people using a vaporiser can be a good solution to sudden endo flares or acute attacks of pain, while using an oil in the evening can provide longer pain relief overnight and potentially help with sleep. Likewise, the composition of the medicinal cannabis you take is important, especially the ratio of THC and CBD, and possibly even others as we are learning more about the importance of other cannabis compounds such as cannabinol. Having a higher THC to CBD ratio might provide more pain relief but also usually results in more impairment (i.e., feeling ‘high’), so people might want to use a CBD dominant product (or a CBD isolate that contains no THC) during the day and then a THC containing product only when their pain is bad. Finally, novel ways of delivering medicinal cannabis are important and exciting new avenues – for example a pessary/suppository that can be placed in the vagina or rectum may be able to deliver a high level of THC but with much lower levels of impairment – so you might be able to get good levels of pain relief but little intoxicating effects. All these new products need to be properly developed and tested, but topical treatments, sprays and other new types of delivery treatment are being developed. 

Disclaimer: The opinions expressed, and the information and language used throughout this research, do not necessarily reflect the views and beliefs of Endometriosis New Zealand.