Amyotrophic lateral sclerosis, Epilepsy, Glaucoma, multiple sclerosis, pain, Parkinson's disaese, Peripheral neuropathy, Tumor

Medical marijuana: dispelling myths and fallacies behind cannabidiol and tetrahydrocannabinol

Virginia Thornley, M.D. Neurologist, Epileptologist


The endocannabinoid system is found naturally in the brain. It is responsible for the sense of well-being one gets after running a 5-mile course. It does not work through endorphins or adrenaline, as some people may think. It works at the level of the endocannabinoid system. There is a community of CBD producers and consumers and it is in this mysterious world that it is well-known to be used in many medical conditions, still shunned by the majority of the medical community, Congress and even patients in general. The 2 most commonly known are cannabidiol and tetrahydrocannabinol. Cannabidiol has medical properties and has a weak affinity to the CB1 receptor which is predominantly found throughout the central nervous system, which is likely why it is found to work in numerous neurological conditions. Tetrahydrocannabinol (THC) is a well-known cannabinoid most notoriously known for the euphoria of kingpins seen on movies propagated by pop culture. Unfortunately, these connotations overshadow the well-known medicinal benefits. Cannabinoids have been used for centuries even in the B.C. period. It was part of the American pharmacopeia in the 1980’s until it was banned in the 1930’s. Slowly, these products are gaining popularity as a treatment for many medical conditions, primarily neurological because the CB1 receptor is so abundant in the nervous system, due to patients becoming more and more frustrated with the adverse effects and ineffectiveness of conventional treatments. In Europe, a combination of THC and CBD have been used in multiple sclerosis patients since 2010.  Animal studies and cell line culture studies demonstrate many potential mechanisms in which CB1 receptors, CBD and THC may be beneficial at the cellular level in many diseases, mechanisms are still being elucidated. It is most commonly used for chronic pain and epilepsy. As with any medication, it may or not be effective for everybody.


How it works–the nitty gritty

Cannabidiol has none of the psychoactive properties as THC. One needs 100 times the amount of CBD to have the same intoxication as THC. Therefore, it works well for those who are reluctant to go this route but who have found conventional medications which do not provide effectiveness, they are simply not cutting it. Because very little is know about its titration, medical marijuana can seem like entering into the world of an apothecary, or such as that found in the medieval days when potions are concocted. Physicians who use it in their treat it similar to a medication and the guidelines are similar start low and go slowly.  Tetrahydrocannabinol is more potent and at higher doses works more effectively for pain control and seizures. THC is used at relatively low concentrations in order to effect its medical properties, at higher concentrations one may run into side effects which offsets its medical value. There are different ratios of CBD:THC, different ratios correspond to different symptoms treated.  CBD is required in conjunction with THC in order to offset the potential side effects of THC. Tolerance does not build in the system such as that seen with opioids, although if one is medical marijuana naive, the lowest dose possible is ideal. There are no side effects of respiratory depression such as that seen with other medications for pain such as opioids.Consult with your treating physician.

Current legal state of affairs

Currently, there are many states that recognize the medical value of medical marijuana with medical marijuana laws allowing the opening of licensed dispensaries. However, the same cannot be said for the federal law.  In some states, the carrying of THC on your person can result in fines and imprisonment. Despite marijuana laws enacted, qualified physicians are at risk for being questioned by authorities, its recommendation and use is not for the faint of heart on the part of physicians and patients. Cannabidiol comes from hemp oil and is not considered illegal. However, anyone who even has 1% hemp oil in their product can still label that product as cannabidiol, which may be the reason why some patients are not getting the full medical effects when bought from the flea market or a vitamin store.  Tetrahydrocannabidiol which is more well-known for its recreational use and concomitant psychoactive properties at very high doses is federally illegal in many states. Many states often have registries so patients who require this may obtain an ID and verify they are under the care of a qualified physician. It can take a few months to obtain an ID because many patients are often at the end of their ropes in terms of effectiveness of medications. Many patients wish to come off opioids or do not like the idea of needing higher and higher pain medications for their chronic illnesses. It may serve as a great antidote for the current opioid crisis that is well-documented in the news or overdocumented in the news. Many mothers order products online from other countries to counteract the illegalities of their states in order to help their child who may be using 4 potent anti-epileptic agents and is now like a zombie because of the number of medications. While physicians are leery suggesting anything that is in category 1, its medical value cannot be disputed. There is too much evidence tipping it towards the other side of the scale. As tPA was in its infancy of use and physicians were hesitant using it due to its hemorrhagic adverse effect and is now the standard of care for stroke protocols, medical marijuana will likely find its way back into the pharmacopeia, the amount of medical evidence is far too compelling to ignore.


In conclusion

In short, when used wisely, cannabidiol is a non-intoxicating effective treatment for many medical conditions especially neurologic, as evidenced by thousands of years of history of its use and current animal models, clinical trials and wider clinical experience in Europe. When cannabidiol is combined with low concentrations of THC, the medical effect is even greater with the entourage effect without the stigmatized psychoactive effects that are usually associated with THC.


multiple sclerosis

Sativex (tetrahydrocannabinol and cannabidiol) and the European experience in medically refractory spasticity in multiple sclerosis

Virginia Thornley, M.D., Neurologist, Epileptologist
March 12, 2018


Sativex has been available in Europe since 2010. It is a combination of tetrahydrocannabinol and cannabidiol at a ratio of 1:1 and has been found to be effective in spasticity resistant to medications in patients with multiple sclerosis. Spasticity is the increased tone seen in the muscles due to abnormalities in the central nervous system such as the white matter lesions seen in multiple sclerosis.

Sativex and medically refractory spasticity in multiple sclerosis

Sativex is a THC:CBD (tetrahydrocannabinol:cannabidiol) preparation taken oromucosally which was approved in European countries for the treatment of medically refractory spasticity in patients with multiple sclerosis. Sativex contains a 1:1 ratio of THC to CBD, where THC interacts with CBD receptors to reduce spasticity while CBD ameliorates the side effects often seen with THC. In one large clinical trial of 1615 patients, 42% showed improvement of spasticity in the first 4 weeks, defined as > or = to 20% reduction in spasticity. The responders were double-blinded and grouped under placebo or THC:CBD, a larger proportion of patients had significant response compared to placebo, > or = to 30% reduction of NRS score for spasticity. 47% had adverse effects including fatigue and dizziness. Reported side effects included psychiatric disturbances, 55 had cognitive (attention problems, cognitive worsening and memory problems) and psychiatric issues (confusion, panic attacks, hallucinations, depression and suicidal ideations). Fatigue, drowsiness, dizziness, gastrointestinal symptoms, mouth discomfort and allergic reactions were other reported side effects. There was no evidence of abuse or addiction in the patients. There were significant side effects deemed unrelated to Sativex including, myocardial infarct, hypertensive crisis (2).

In the original MOVE 2 trial in Italy, in the 322 patients studied, the NRS numerical rating scale decreased by -19.1% from baseline time to 3 months of treatment with Sativex. At visit 3 at 3 months, 24.6% were considered relevant responders to the medication with 30% or more reduction in spasticity. Side effects of >1% included somnolence, dizziness, and fatigue. 41 patients reported side effects 3 were serious side effects of which one was not related (3).


Sativex and studies in Germany, United Kingdom, Switzerland and Spain

Sativex was first approved in Spain and the United Kingdom in 2010 for use in spasticity related to multiple sclerosis. Data were collected to study continued efficacy and safety profiles.  941 patients (761 from the UK, 178 from Germany and 2 from Switzerland) were studied. Data was collected up until January of 2015.  A patient registry was set up as per guidelines before new medications are approved. Patients from the UK were 22% of the patients registered in the UK using that medication since 2010. Continuation rates were 1 year for 68% of patients. Among those who stopped it, 30% cited lack of effectiveness and 25% described side effects. Some significant side effects include suicidality in 2% and depression in 6%. There was no evidence of abuse, addiction or misuse. The fatigue was within the known safety margins of the drug. The patients used on average 5.9 +/- 4.9 sprays per day

In Spain, 204 patients were evaluated. After 6 months, 143 (70.1%) had benefited from using it for spasticity. After 12 months 64.7% derived beneficial effects. The average dose was 6.6 sprays a day. 41 patients had side effects consisting of psychiatric events, falls, reduced the ability to drive and others. Both study groups in the UK, Germany, Switzerland and in Spain both derived benefits justifying continued used of Sativex. Adverse effects were low, and the mean use of sprays was between 5.9-6.6 which was lower than the clinical trial using 8 sprays (4).

Sativex and timeline when it is found to be ineffective

In one large study in Italy involving 30 multiple sclerosis centers, the discontinuation profile was studied. Patient data from 30 MS centers were collected from a period of January 2014 to January 2015. 39.5% of patients disconnected treatment with Sativex. Spasticity was studied using the EDSS or expanded disability status scale and the patient NRS numerical rating scale 0-10 for spasticity. Information was collected at baseline (T0), 4 weeks (T1), 3 months (T2) and 6 months (T3).

Spasticity was noted in 1615 patients. 1597 (39.5%) discontinued treatment. Of those, 24.8% did not reach 20% effectiveness using the NRS scale. Reasons of discontinuing include lack of effectiveness 23%, side effects 16.3% and lack of compliance 0.8%, lost to follow-up 0.4%, patient choice 0.3% and unknown reasons 2%. Analysis showed that an increase in the NRS scale by 1 point at baseline time corresponded to a lower rate of discontinuation. While an increase in the NRS scale at timeline 2 or at 4 weeks corresponded with worsening spasticity and a higher non-responder rate. They concluded that Sativex is a good option for spasticity and by 4-6 weeks, patients can be reliably identified as responders or non-responders to avoid the cost burden on the healthcare system (1).

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  1. Messina, et al, “Sativex in resistant multiple sclerosis spasticity: discontinuation study in a large population of Italian patients (SA.FE. study), Public Library of Science PLoS One, 2017, 12(8) e0180651
  2. Patti, et al, “Efficacy and safety of cannabinoid oromucosal spray for multiple sclerosis spasticity,” Journal of Neurology, Neurosurgery and Psychiatry, 2016, Sep., 87(9):944-951.
  3. Trojano, et al, “Effectiveness and tolerability of THC/CBD oromucosal spray for multiple sclerosis spasticity in Italy: first data from a large observational study,” European Neurology, 2015, 74:178-185,
  4. Fernandez, et al, “THC:CBD in daily practice: available data from UK, Germany and Spain,”European Neurology, 2016, 75 (supp 1);1-3,
Epilepsy, Glaucoma, pain, Peripheral neuropathy, Tumor

Medical Marijuana: why the huge disconnect between physicians, laws, policies, and patients?

Virginia Thornley, M.D., Neurologist, Epileptologist

March 11, 2018


A patient comes to you asking “Doc, my seizures are getting worse, I really hate the side effects of my medications, I really want to go a different route. Have you heard about medical marijuana?” You start sweating profusely, fidgeting in your seat, thinking of every single reason why not to recommend it and come up with  the standard response, “uh, well, I’m not qualified to recommend it and it’s not FDA approved, plus we don’t really know much about it there could be so many side effects.” And then we have the oldie but goodie response, “there’s not enough large randomized control trials to recommend it.” This scene plays 100,000 times over if not a million times over in physician offices across the country. Patients who are disillusioned with adverse effects of medications are looking towards alternative therapy. As surprising as it sounds, patients with chronic pain do not want to get intoxicated by opioids. In fact, some want to be tapered off of them or refuse them all together. Patients with end-stage cancer at the terminal stage of their lives wish to live a comfortable and humane existence without the need for more chemotherapeutic medications or pain medications that consistently make them feel like a zombie. While other patients with epilepsy may be on 4 different anti-epileptic agents and can no longer function or have a good quality of life because of side effects. There are two sides to every coin.

Why you should be educated on cannabidiol and THC use in medical conditions

If patients do not get their answers from their trusted physicians who they trust with their well-being, their health, the temples of their souls, they will go to great lengths in procuring this knowledge. This is via various sites on the internet some of the dubious nature others are from high quality companies that have been in business even before this seeming treatment fad started. Or, the information may be obtained from their brother-in-law’s friend’s hair stylist who is now pain-free after going through a long course of pain medications including ablative treatments, physical therapy, and acupuncture and has a physician who does recommend it. Like it or not, cannabidiol and tetrahydrocannabinol are alternative treatment options and are gaining more and more traction. To ignore it is to be complacent with the changing direction and landscape of medicine. As patients become more and more disillusioned by the limitation of conventional treatments, attention is directed towards alternative regimens. It is not just for the yoga-practicing patient looking for more natural methods, one sees the sweet 83-year-old gentleman who must be someone’s grandfather with the chronic hip pain of 50 years who have failed opioids and is simply looking for pain relief.


Is there any evidence that it works?

The endocannabinoid pathway is found naturally in the system. It is responsible for the runner’s sense of wellbeing one gets after a 5-mile run and the pleasant mood you get after a 1-hour work-out with Zumba. There are 2 receptors in the system CB1 receptor which has the highest number of brain cells and the CB2 receptor which is found predominantly in the immune system. There are 2 common cannabinoids cannabidiol and tetrahydrocannabinol which exert various medical effects. Cannabidiol (CBD) has a weak affinity for the CB1 receptor and one needs 100 times the amount to get the same euphoria that one gets from tetrahydrocannabinol, the bane of every ER physician. Unfortunately, the side effects of euphoria of THC have preceded its popularity as a medical product. Little do we know it was once used for hundreds of years as a medication before the psychoactive properties were exploited for recreational purposes. In urologic culture cell lines, it is found that cannabinoids may reduce proliferation of cancer cells and reduce the pro-inflammatory microenvironment that is necessary for metastatic conditions (1). Human studies are still needed to determine a reduction in tumor loads. THC receptors are found in retinal cells and may be found to reduce intraocular pressure in glaucoma (5, 6). Cannabidiol is found to bind to the 5HT1 receptor which reduces anxiety. THC has been well-established in the mouse model to promote the inhibitory control of excitatory pathways in the hippocampus, where seizures commonly arise (8). There is an increase in CB1 receptors after prolonged seizures suggesting a compensatory response.  It has been used in combination and found in several randomized control trials to reduce the frequency of seizures by as much as 36% in medically refractory patients (2). It is well-established that cannabinoids reduce pain refractory to conventional medications (3). It has been found in bench research to be an antioxidant and have anti-inflammatory properties (4, 7). Some studies cite side effects of somnolence, nausea, dysphoria, however, it is not clear what was the quality of cannabinoids or dosages were used. At high doses, while THC can reduce pain it may also result in side effects, which is why it is usually used in combination with CBD which ameliorates the side effects of THC.  In addition, cannabidiol by itself has no euphoria and it takes 100 times the amount to achieve intoxication seen with THC use. Synthetic products will have more side effects than products that are organic meaning only of natural materials.

Given the huge amount of evidence in several different medical conditions (3), the results should overwhelmingly be towards a push in using cannabinoids more frequently. However, because of the cynicism of the public, physicians even of patients, who have been exposed more frequently to the harmful psychoactive side effects, the benefits are far overshadowed. More clinical randomized controlled trials are needed. Most literature cites small numbers of patients enrolled in studies or review multiple medical centers where the conditions are not uniform. In addition, some of the patients that would benefit the most are the least in numbers such as those with rare neurological conditions such as Dravet syndrome or Lennox-Gastuat syndrome.


In conclusion

As it still stands, many states still do not recognize the medicinal value of cannabidiol or tetrahydrocannabinol. In some states, medical physicians are not allowed to recommend it and put themselves at risk for FBI questioning in even suggesting its use. It is not uncommon for patients to move states or order from other states or countries to procure this liquid gold that is supposed to work wonders. Only time will tell if this is a passing fad and if there are long-standing side effects, however, as of current standing, medical marijuana is here to stay. As far as the literature goes, there are beneficial results but it is a cautionary tale as more studies in large human trials are still needed. As with any new preclinical data, the preclinical status may get ahead of itself and human trials do not replicate the desired results. But from the small clinical trials in seizures, pain, nausea, anxiety, and loss of appetite, the results are promising while more research is needed for anti-tumor effects in humans.

As with any medication, there will be clear-cut side effects just as with any other medication which is why more studies are needed to determine the least amount with the least amount of side effects. In some studies,  amounts upwards of 50mg/kg (2) is used the high amounts likely responsible for causing side effects, which is far higher than that cautioned by medical marijuana dispensaries. It will take patients time to wrap their heads around taking guidance from a fresh-faced 20-year-old millennial at the spa-like dispensary which is currently the norm at most dispensaries, who likely knows much more than even most medical professionals. It seems it will take even longer in Congress to understand the potential benefit of cannabinoids from a medical standpoint especially with the present opioid epidemic. Countries in Europe have far surpassed the United States when it comes to cutting-edge treatments. Perhaps, it will take even longer for the medical community to see the medical potential with their exposure to the sinister side of tetrahydrocannabinol seen in patients in the ER for non-medical reasons, which may be one of the most challenging stumbling blocks.

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  1. Ghandhi, et al, “Systemic review of the potential role of cannabinoids as anti-proliferative agents for urological cancer,” Can. Urol. Assoc. J., 2017, May,-April., 11(3-4):E138-E142.
  2. Devinsky, et al, “Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial,” Lancet Neurology, 2016, Mar., 15(3):270-280.
  3. Petzke, et al, “Efficacy, tolerability, and safety of cannabinoids for chronic neuropathic pain: a systemic review of randomized controlled studies,” Schmerz, 2016, Feb., 30(1):62-88.
  4. Rajan. et al, “Gingival stromal cells as an in vitro model: cannabidiol modulates genes linked with amyotrophic lateral sclerosis,” Journal of Cellular Biochemistry, 2017, Apr., 118(4):819-828.
  5. ElSohly, et al, “Cannabinoids in glaucoma II: the effect of different cannabinoids on intraocular pressure on rabbits,”Current Eye Research, 1984, Jun., 3(6):841-50.
  6. Jarvinen, T., “Cannabinoids in the treatment of glaucoma,” Pharmacology and Therapeutics, 2002, Aug., 95(2):203-20.
  7. Carroll, et al, “9-Tetrahydrocannabinol exerts a direct neuroprotective effect in human cell culture model of Parkinson’s disease,” Neuropathology and Applied Neuropharmacology, 2012, Oct., 38(6):3535-547.
  8. Kaplan, et al, “Cannabidiol attenuates seizures and social deficits in a mouse model in Dravet syndrome,” Proceedings of the National Academy of Science, 2017, Oct.
Closed head injury

Closed head injury: electroencephalographic changes in post-concussive syndrome

Virginia Thornley, M.D., Neurologist, Epileptologist

March 10, 2018


A concussion occurs commonly as high-speed vehicular accidents become more common in today’s fast-paced world. In addition, it occurs frequently in sports-related activity such as football or boxing. The brain is composed of millions of connections and though a patient may complain of several neurological complaints, it is not often manifest in neuroimaging studies, except perhaps diffusion tensor imaging. More often than not, a good clinician can diagnose symptoms of post-concussion syndrome based on neurological symptoms and a preceding event. During injury, there is shearing of thousands of axons diffusely throughout the brain. The contrecoup effect of the injury occurring over the frontotemporal poles produces damage causing a myriad of neurological symptoms. On EEG, non-specific changes can be found corresponding with the degree of injury. There is slowing of the posterior dominant rhythm and excessive theta rhythms which eventually clears after weeks or months of recovery (1).  Some patients, however, are left with recurrent symptoms such as post-concussion headaches, or dizziness or sensations of discomfort. On EEG, some studies show post-concussion symptoms correlating with bursts of theta rhythms.

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EEG findings in a few minutes spanning more than 6 months

In animal studies, the EEG shows high voltage sharp waves followed by diffuse background suppression which can last a few minutes. This is followed by diffuse slowing that normalizes after 15 minutes in one study occurring between 10-60 minutes (2). Over a few hours to weeks, there are increased theta and delta rhythms and reduced ratio of theta to alpha frequencies. there was an increase in delta activity in the posterior regions. There are brief periods of reduced delta: alpha ratios. In one study called the “Belfast studies,” amnesia was evaluated in 73 patients at 24 hours and 6-week follow-up with EEG and brainstem auditory evoked potentials (BAEP). It was found that amnesia did not have EEG correlate but correlated with abnormal BAEPs suggesting amnesia was derived from brainstem dysfunction rather than cortical dysfunction. Over weeks to months, there are reduced alpha and increased delta rhythms are noted. In the Belfast studies, there was more persistent left temporal slowing, which seemed to correlate with chronic symptoms when it persisted beyond 6 months. After more than 6 months, there were increased delta activity and fewer alpha rhythms (2).

Other EEG findings in closed head injury and part-seizure like activity

In one retrospective study of 3 groups of veterans at a Veteran Affairs Medical Center,  30 comprised of normal subjects with normal EEGs, 30 had EEG’s with non-paroxysmal theta delta slowing and 38 patients had theta bursts. The patients with episodes of theta bursts seemed to have corresponding partial seizure-like clinical symptoms. Patients with head injury reported episodic symptoms across all 3 groups. These findings conclude that clinicians may want to evaluate patients for seizure-like activity in the context of closed head injury and presence of bursts of theta activity (3).

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  1. Nuwer, et al, “Routine and quantitative EEG in mild traumatic brain injury,” Clinical Neurophysiology, 2005, Sep., 116(9):2001-2025
  2. Haneef, et al, “Electroencephalography and quantitative electroencephalography in mild traumatic brain injury,” Journal of Neurotrauma, 2013, Apr., 30(8):653-656.
  3. Roberts, et al, “Theta bursts, closed head injury, and partial seizure-like symptoms: a retrospective study,” Applied Neuropsychology, 2001, 8(3):140-7.

The state of medical marijuana in urologic tumor burden control through inflammation reduction and reduction of tumor cell proliferation in cell cultures

IMG_0923_previewVirginia Thornley, M.D., Neurologist, Epileptologist

March 10, 2018


Cannabinoids, which are cannabis plant-based non-synthetic medications including cannabidiol (CBD) and tetrahydrocannabinol (THC), are being used more frequently in palliative care to reduce the pain associated with end-stage cancer. In addition, it is well-established that it helps with lack of appetite found in cancer patients and reduces nausea and vomiting associated with many of the chemotherapeutic drug regimens (2), although current studies are needed given the newer chemotherapeutic agents available. Although there were more reported side effects using cannabinoids including euphoria, dizziness, dysphoria, and somnolence it is not clear if low dosages were used or what the ratio of cannabidiol to THC was used. It is well known that using higher doses of THC products will control the pain more adequately but at high doses may cause the side effect. Cannabidiol alone has no intoxication or euphoria and a low dose of cannabidiol combined with THC will ameliorate some of the side effects of THC.   Questions regarding its anti-tumor properties often arise which physicians managing patients with cancer are not prepared to answer. Since most of the studies are done in animal models and are often difficult to translate into the human model, research is needed with randomized clinical trials in the patient population. Currently, most anti-tumor literature is found in cell culture lines and extrapolated. The future is promising but large human studies are needed.

In renal cancer

Cannabinoids work through 2 receptors CB1 found in highest numbers in the brain and CB2 which is predominant in the immune system. In renal cancer, the CB1 receptor is found to be lower in number which may suggest that a reduced number of cannabinoid receptors leads to less control over the proliferation of tumor cells. There is a high concentration in the proximal convoluted tubule which suggests that a down-regulation may be associated with less inhibition of tumor cell proliferation (1). In another study, CB1 receptors were similar in chromophobe tissue lines were similar to renal cells with no tumor. This may serve as a diagnostic tool for differentiating it from clear cell tumors. It is often difficult to differentiate between the two. Chromophobe tumors have the same number of CB1 receptors while clear cell carcinomas have less CB1 receptors. This is important from the histological and diagnostic standpoint (1).


In prostatic cancer

In prostate cancer, some mechanisms suggested through studies include working through phosphatase induction. It was found that CB1 and CB2 are expressed during later stages of prostatic cancer. Treatment of prostate cancer culture cells with cannabinoids was found to reduce the multiplication of tumor cells, suggesting a role through apoptotic mechanisms. The effect was dependent on dosage. In another study, cannabinoids were found to increase cytokine IL-6 in prostate cancer that is androgen resistant. This suggests that CB2 agonists may play an important role in reducing epithelial cell proliferation and may lead to a means to treat prostatic cancer (1). More studies are needed to elucidate mechanisms leading to treatment of prostatic cancer.

In bladder cancer

There is much evidence that inflammation found in cancer may lead to the metastatic stage. Cancer can lead to a pro-inflammatory state inducing cytokine and growth factor release leading to the environment conducive to metastasis and invasion of cancer cells into other tissues. In one study of the CB1 and CB2 receptors, it was found that activation of CB1 receptors played an important role in regulating tumor cell proliferation while CB2 was important in influencing an inflammatory state (1). Further studies are needed to further elucidate the mechanisms of cannabinoids on bladder cancer.



  1. Ghandhi, et al, “Systemic review of the potential role of cannabinoids as anti-proliferative agents for urological cancer,” Can. Urol. Assoc. J., 2017, May,-April., 11(3-4):E138-E142.
  2. Smith, et al, “Cannabinoids for nausea and vomiting in adults receiving chemotherapy,” Cochrane Database Syst. Rev., Nov., 12(11):CD009464. doi: 10.1002/1465

Cannabidiol: mechanisms and efficacy in medically refractory epilepsy

Virginia Thornley, M.D., Neurologist, Epileptologist

March 9, 2018


One of the most challenging therapeutic goals are to keep patients with epilepsy seizure free. Once a patient is found to be medically refractory, it is not unusual to find patients on 3-4 medications for seizure control. However, oftentimes, the means to the end is often wrought with its own challenges with patients suffering side effects placing their quality of life secondary to the medical control of their condition. More and more patients and their families are turning towards a more naturalistic approach including diet and cannabidiol use which has fewer side effects as a means to control seizures. The literature is fraught with a paucity of scientific data with small clinical trials, animal models, and anecdotal data. Larger clinical randomized control trials are pursued.


Mechanisms of Cannabidiol and THC

In the brain, there is the natural endocannabinoid system. Endocannabinoids are released after exercise referred to as the runner’s high which contributes towards our sense of well-being. In the endocannabinoid pathway, cannabidiol has a low affinity to the CB1 receptor and modulates THC tetrahydrocannabinol by blocking CB1 receptor. It is thought to modulate THC by blocking the CB1 receptor acting as an inverse CB1 agonist (2). This may be the mechanism behind combining CBD with THC, CBD modulates the side effects of THC making it less available to exert its effects. Delta9THC is found to work at the level of the CB1 receptors which are rich in the brain and CB2 receptor which is more predominant in the immune system. THC can bind to other targets exerting inflammatory properties. CBD has less binding capabilities to CB1 receptors and is thought to exert its effect by working through other mechanisms such as voltage-gated potassium and sodium channels and the GRP55 in controlling seizures. Cannabinoids are lipid binding or lipophilic making it less available within the system making it challenging to deliver (3).

Cannabidiol clinical trials

In one study, 216 patients were enrolled and followed 3 months after administration of the first dose cannabidiol. Initially, the dose was 2mg/kg which was titrated up to 50mg/kg. 76% were enrolled in the safety profile study and 64% were enrolled in the efficacy profile study. In the first group for safety, 20% had Dravet syndrome and 19% had Lennox-Gastaut syndrome. Side effects were noted in 79% of the patients in the safety group. These include somnolence, diarrhea, seizures (11%), fatigue and reduced appetite. Five disenrolled due to adverse effects, 30% had serious side effects including 1 death of consisting sudden death syndrome. 12% had serious side effects including status epilepticus which may have been related to cannabidiol use. The median reduction of seizures was 36.5%. The study concluded that cannabidiol may be an effective strategy for reducing seizures in medically refractory seizures. The flaw with the study is that the doses at the higher end may have been too high for the patients to tolerate, a lower titrated dose may have been equally effective in controlling seizures and minimizing side effects. Nevertheless, the results were promising as it proves to be beneficial in controlling some of the seizures.



  1. Devinsky, et al, “Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial,” Lancet Neurology, 2016, Mar., 15(3):270-280.
  2. McPartland, et al, “Are cannabidiol and 9 delta tetrahydrocannabivarin negative modulators of the endocannabinoid system? A systematic review,” British Journal of Pharmacology, 2015, Feb., 172(3):737-53.
  3. Gaston, et al, “Pharmacology of cannabinoids in the treatment of epilepsy,” Epilepsy Behavior, 2017, May, 70(Pt B):313-318.


Peripheral neuropathy

Peripheral neuropathy: chronic pain amelioration with cannabidiol and tetrahydrocannabidiol

Virginia Thornley, Neurologist, Epileptologist

March 8, 2018


Chronic pain from neurological conditions such as neuropathic pain can become refractory to conventional medications. Interest is directed towards novel ways of treatment such as cannabidiol and THC which are known in animal models to be anti-inflammatory, analgesic and neuroprotective. Cannabinoids are being used more commonly in patients who have failed medical treatments and remain a viable option in the treatment of pain. Many animal models point towards mechanistic evidence that cannabidiol and THC reduce severity and frequency of pain syndromes. Cannabidiol is non-intoxicating and is an alternative form of management. With THC, the level of pain relief is higher but with that comes a higher risk of side effects at greater doses.




Cannabidiol and neuropathic pain in joints

Osteoarthritis involves inflammation, pain, and neuropathic pain. Cannabidiol was studied in rat models and its effect on pain from the joints and nerves. In end-stage osteoarthritis, cannabidiol reduced joint afferent pain. Transient joint inflammation was reduced using cannabidiol. CBD application used prophylactically demonstrated lack of development of pain and inflammation during later stages.

One study suggests that chronic neuropathic pain might be suppressed by cannabidiol through alpha 3 glycine receptors. In mice lacking these receptors, there is no cannabidiol analgesic effect. Cannabinoids are found to support glycine activity in the dorsal cell neurons in rats. This suggests that glycinergic cannabinoids may provide a potential therapeutic option in treating neuropathic pain. There is lack of psychoactive side effects or development of tolerance (1).

Cannabidiol and neuropathic pain studies

In one review of 15 randomized controlled trials against placebo with a total of 1619 patients, 13 studies consisting of 1565 patients reported a reduction of pain compared to placebo which was statistically significant. There was a frequency reduction in pain of 30%. 10 studies used nasal tetrahydrocannabinol /cannabidiol and 3 used synthetic cannabidiol while 2 used medical cannabis. They concluded that cannabidiols were marginally superior and had greater side effects than placebo. It is a treatment option for patients who have failed several lines of treatment. Some flaws that can be seen in this study is that with this study, some centers used synthetic forms of cannabinoids and others used a combination of THC and cannabidiol. Synthetic medical marijuana has a different quality compared to a product that is purely organic and made from natural materials. High doses of THC is known to cause side effects while with lower doses of THC pain relief may be obtained with fewer side effects. It is not clear how pure the products are which were being administered.

In one large study of 303 patients with peripheral neuropathy, 128 used CBD/THC spray and 118 randomized to placebo. End-point was a 30% responder rate using the PNP numerical scale 0-10. There was a substantially higher number of responders for CBD:THC but not statistically significant. Quality of life and sleep improved in those with CBD/THC nasal spray. They concluded that use of CBD/THC helped improve pain from peripheral neuropathy and there were no substantial adverse effects from the patients studied (3).


  1. Xiong, et al, “Cannabinoids suppress inflammatory and neuropathic pain by targeting alpha 3 glycine receptors,” Journal of Experimental Medicine, 2012, Jun., 209(6):1121-1134.
  2. Petzke, et al, “Efficacy, tolerability, and safety of cannabinoids for chronic neuropathic pain: a systemic review of randomized controlled studies,” Schmerz, 2016, Feb., 30(1):62-88
  3. Serpell, et al, “A double-blind, randomized, placebo-controlled, parallel group study of THC/CBD spray in peripheral neuropathic pain treatment,” European Journal of Pain, 2014, Aug., 18(7):999-1012.