Going to pot: using cannabis derivatives as medicinal treatments
Broadly defined as any cannabis derivative used as a medicinal treatment, medical cannabis can take the form of dried cannabis plant material or products made from purified extracts of the plant
Connemara-based Robert Joyce was diagnosed with multiple sclerosis (MS) over three decades ago. The 54-year-old former business consultant was holidaying in San Francisco when he first experienced the “incredible impact” of medical cannabis (MC) in 2019. Suffering constant head pain from a car accident five years prior, he says that the accident also triggered a worsening of his spasticity—the stiffness and involuntary muscle spasms associated with his MS—to the point where traditional medicines were proving less effective.
“When I took the cannabis oil, my ability to walk really improved to the extent that I was able to walk all around Alcatraz, which is a very hilly island [in San Francisco],” he says. “My mobility improved dramatically, and another added benefit—I found that I had much greater tolerance in how I managed the pain. I was suddenly able to concentrate and sit with all the noise, sound, and activity of a restaurant without finding my pain escalating.”
Medical cannabis is used in a very different context to recreational cannabis. Broadly defined as any cannabis derivative used as a medicinal treatment, MC can take the form of dried cannabis plant material or products made from purified extracts of the plant. Though cannabis has been used medicinally for centuries, the last decade has seen a notable resurgence in people turning towards the plant for everything from palliative care and neurological disorders to chronic pain and the menopause.
“When I started working in this area 20 years ago, [scientists] had identified about 60 or 70 ‘phytocannabinoids’ or bioactive chemicals in the cannabis plant, but now today there's over 100 of these known,” says Dr Eric Downer, an associate professor in human health and disease at Trinity College Dublin, whose research lab focuses on MS and the medicinal properties of cannabis.
Downer explains that phytocannabinoids interact with your body’s endocannabinoid system, which governs a whole host of critical functions — including sleep, learning, emotional processing, and pain control. The most heavily characterised of these chemicals—tetrahydrocannabinol (THC) and cannabidiol (CBD) — boast potential therapeutic effects but each, according to Downer, affects the body in very different ways.
“The main distinction between THC and CBD is that THC is the main euphoric component of the plant. It acts on receptors in the endocannabinoid system to produce that characteristic ‘high,’ whereas CBD, which has different receptor targets, does not induce euphoria,” he says.
While CBD formulations are widely available in health food stores, THC-infused products remain subject to the tightest control under the Misuse of Drugs Act 1977 to 2016. One exception is Sativex, a cannabis-based medicine authorised in Ireland and available as a prescription for people with MS who are experiencing spasticity. Other quality-standard cannabis-based products supplied outside Ireland and not approved by the Health Products Regulatory Authority (HPRA) require an Irish-registered medical consultant to obtain an import license from the Minister of Health.
In December 2016, Tristan Forde, suffering from a severe genetic form of epilepsy known as Dravet Syndrome, became the first Irish patient to be treated via a ministerial licence. Earlier this year in a Dáil debate, Health Minister Stephen Donnelly revealed that 36 patients are currently being treated by this same MC access route, closely monitored by their consultants.
When Joyce gained access to a cannabis-based treatment for his MS through a ministerial license, he says his quality of life improved remarkably. For the last two years, his consultant has prescribed Bediol, a cannabis-based oil containing a ratio of THC 6.3% and CBD 8% from Transvaal Pharmacy in the Netherlands—the same pharmacy where MC campaigner Vera Twomey sourced MC for her late daughter Ava Barry.
Though originally prescribed Sativex, Joyce experienced distressing side effects, such as lesions under his tongue (due to sublingual administration), gastrointestinal reflux, and bowel issues. Switching to Bediol also reduced his monthly costs from €600 to €150, a necessary reduction given that he was on disability allowance and Sativex was not then covered by the Medical Cannabis Products Reimbursement Scheme.
Since Joyce’s first experience with MC, cannabis-based products have become available to Irish patients through the HSE’s Medical Cannabis Access Programme (MCAP), which has been fully operational since 2021. To date, 49 patients have been treated through MCAP, which was established based on the recommendations of a 2017 HPRA report.
Clinical guidelines for Irish consultants restrict MC to patients with three conditions that have demonstrated resistance to all other treatments: spasticity associated with multiple sclerosis (MS), intractable nausea and vomiting associated with cancer chemotherapy, and severe, refractory (treatment-resistant) epilepsy.
“The pain that I have in my head is not an acceptable reason to get MC under the MCAP and yet the pain relief I get from it allows me to be more effective in my life,” says Joyce.
According to Dr David Finn, professor and head of pharmacology and therapeutics and the founding co-director of the Centre for Pain Research at the University of Galway, clinical evidence for the use of MC is limited. He says there is a shortage of high-quality randomised controlled trials (RCTs) to back its long-term efficacy and safety in humans. However, he suggests that there is enough evidence from other sources, including population health studies, to consider expanding the MCAP to treat severe, treatment-resistant chronic pain.
Why might this be important? In Finn’s view, when it comes to relieving chronic pain, over-the-counter CBD is unlikely to be as effective as a prescribed THC-infused product. Unlike CBD, THC has been shown to have “analgesic or antinociceptive [pain-reducing] effects” through direct activation of CB1 and CB2 receptors in the body.
Nonetheless, Finn says, “We need more research to understand if and to what degree MC, used under expert medical supervision, leads to dependence. It would also be necessary to compare this with other pain medications, like opioids, that are known to have a dependence liability.”
Similar to research on cannabis dependence, the majority of studies on the risk of cannabis-induced psychosis focus on cannabis use in recreational or non-medical contexts, where the THC content tends to be substantially higher. One such recent study, based on the data of 233,475 people who use cannabis (PWUC) internationally, found that one in 200 PWUCs will experience “acute self-limiting psychotic symptoms” in their lifetime.
Additional studies have linked cannabis use with the onset of mental health disorders, such as depression, especially in the young. However, drawing conclusions from these findings requires caution since the correlation can be interpreted in two ways: people who use cannabis may be more vulnerable to mental health issues, or individuals experiencing mental health problems may be more inclined to self-medicate with cannabis.
For the last two years, Katie* has been combining cannabis with therapy and other psychological tools in the management of her complex PTSD. The social worker, who is in her mid-40s and based in Galway, says that low-dose use of cannabis has enhanced her capacity to work and function in the world by dulling her constant sense of terror.
“The medication that I have [been prescribed] can be either very heavy—it can make me feel like I need to go to sleep or goof off—or else it just makes me completely [emotionally] numb,” she says.
“But I've spent half my life being numb, and I don't like it. If I smoke a joint or have a vape, it just gives kind of a soft blur to the world and the edges and stops my brain from going five million miles an hour. [The cannabis] helps me to work and to continue functioning, without taking away my emotions and without adding a bunch of side effects into the mix.”
Individuals like Katie are sourcing their cannabis from the black market since neither complex PTSD nor any other mental health condition is currently specified by MCAP. Self-medicating with cannabis, however, in the absence of close monitoring by a consultant, presents several potential risks. In addition to the unknown long-term health effects, these can include adulteration of cannabis plant material and harmful drug interactions with prescription medicines.
Some research groups, among them Downer's lab, are exploring the power of 'free therapeutics' such as exercise to modulate the endocannabinoid system in managing the symptoms of neurological disorders. While future research might supply an equally effective alternative for 'biohacking' the endocannabinoid system, Katie hopes that MCAP will expand its scope in the meantime.
With a view to bridging the access gap, Oleo, the only Irish-based supplier of medical-based cannabis products, has partnered with the German-based MC clinic, Canncura. According to Oleo consultant Natalie O’Regan, the company plans to open several private clinics in Ireland in the new year, applying for a ministerial licence on behalf of patients for a broader range of chronic health conditions.
"In countries like Germany and the UK, private MC clinics offer broader access to cannabis-based products for a whole range of chronic conditions," says O'Regan.
Medicann, a private clinic based in the Isle of Man, has already begun registering Irish patients and training Irish-registered doctors to prescribe. Gary Whipp, CEO of Medicann, says its “current waitlist [of Irish patients] is in the hundreds and is growing daily.”
While it is clear that MC can positively affect the lives of some, further high-quality research is needed to determine its long-term safety and effectiveness across different patient groups.
