Tag Archives: CBD

Tumor

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

Introduction

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).

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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.

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Reference

  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
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Peripheral neuropathy

Peripheral neuropathy: chronic pain amelioration with cannabidiol and tetrahydrocannabidiol

Virginia Thornley, Neurologist, Epileptologist

March 8, 2018

Introduction

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.

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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).

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References
  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.

 

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Glaucoma

Tetrahydrocannabinol and novel mechanisms in reducing intraocular pressure in glaucoma

Virginia Thornley, M.D.,  Neurologist, Epileptologist

February 28, 2018

Introduction

The endocannabinoid system is composed of 3 systems: (the cannabinoid receptors, (2) endocannabinoid transportation system and (3) enzymes that break down the ligands. Two endocannabinoids anandamide (AEA) and 2-arachidonyl glycerol (2-AG) are elevated in response to a wide variety of pathological events. This suggests a compensatory response of endocannabinoids in response to damage or pathology within the system (3). Activation of the endocannabinoid system appears to correlate with cell repair and survival. The G-receptors discovered called CB1 and CB2 trigger transducer signal cascades and influence peripheral central cell functions.

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Cannabidiol in glaucoma

Cannabidiol is becoming a topic of hot debate in pain, anti-tumor effects, epilepsy and in glaucoma.  Glaucoma can result in increased intraocular pressure resulting in damage to the optic nerve at the retinal attachment. There is the narrowing of the visual field and eventual blindness through retinal damage. and blindness. Cannabinoid receptors have been found in the ocular cells leading to speculation of benefits of cannabinoids in glaucoma.

In one study of 32 different types of cannabinoids, it was found that certain derivatives of delta 9THC and delta 8THC were more effective at lowering intraocular pressure in glaucoma than the parent derivative cannabidiol (1).

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Mechanism for treating glaucoma

One possible mechanism in ameliorating intraocular pressure is by suppressing N-methyl D-aspartate or NMDA receptor excitability, increasing neural vasculature circulation, suppressing apoptosis and damaging free radicals. Separation of the novels effects appears possible from the toxic side effect through novel technique (2).

Involvement of cannabinoid and their receptors in retinal cells have been well documented in fish cells to primates and more recently in neurodegeneration and neuroprotection. There is a fine balance of biosynthetic and degrading enzymes that influence endocannabinoids and exert neuroprotection during trauma, inflammation, ischemia and neurotoxicity found in brain damage (4).

In addition, in one study in 21 dogs, when 2% of tetrahydrocannabinol was applied, the intraocular pressure was reduced (5) which was found statistically significant.

 

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References

  1. 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.
  2. Jarvinen, T., “Cannabinoids in treatment of glaucoma,” 2002, Aug., 95(2):203-20.
  3.  Karanian, et al, “Cannabinoid drugs and enhancement of endocannabinoid responses: strategies for a wide array of disease states,” Current Molecular Med., 2006, Sep., 6(6):677-84.
  4.  Rapino, et al, “Neuroprotection by endocannabinoids in glaucoma and retinal neurodegenerative diseases,” Current Neuropharmacology, 2017, Jul., doi:10.2174 (Epub ahead of print)
  5. Fischer, et al, “Effects of a topically applied 2% delta-9-tetrahydrocannabinol ophthalmic solution on intraocular pressure and aqueous humor flow rate in clinically normal dogs,” American J. Vet. Res., 2013, Feb., 74(2):275-80.

 

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Glaucoma, Uncategorized

9Tetrahydrocannabinol and novel mechanisms in reducing intraocular pressure in glaucoma

Virginia Thornley, M.D.,  Neurologist, Epileptologist

February 28, 2018

Introduction

The endocannabinoid system is composed of 3 systems: (the cannabinoid receptors, (2) endocannabinoid transportation system and (3) enzymes that break down the ligands. Two endocannabinoids anandamide (AEA) and 2-arachidonyl glycerol (2-AG) are elevated in response to a wide variety of pathological events. This suggests a compensatory response of endocannabinoids in response to damage or pathology within the system (3). Activation of the endocannabinoid system appears to correlate with cell repair and survival. The G-receptors discovered called CB1 and CB2 trigger transducer signal cascades and influence peripheral central cell functions.

13909252_10154408552708841_6462398358021475581_o

Cannabidiol in glaucoma

Cannabidiol is becoming a topic of hot debate in pain, anti-tumor effects, epilepsy and in glaucoma.  Glaucoma can result in increased intraocular pressure resulting in damage to the optic nerve at the retinal attachment. There is the narrowing of the visual field and eventual blindness through retinal damage. Cannabinoid receptors have been found in the ocular cells leading to speculation of benefits of cannabinoids in glaucoma.

Mechanism for treating glaucoma

One possible mechanism in ameliorating intraocular pressure is by suppressing N-methyl D-aspartate or NMDA receptor excitability, increasing neural vasculature circulation, suppressing apoptosis and damaging free radicals. Separation of the novels effects appears possible from the toxic side effect through novel technique (2).

Involvement of cannabinoid and their receptors in retinal cells have been well documented in fish cells to primates and more recently in neurodegeneration and neuroprotection. There is a fine balance of biosynthetic and degrading enzymes that influence endocannabinoids and exert neuroprotection during trauma, inflammation, ischemia, and neurotoxicity found in brain damage (4).

THC studies and glaucoma

In a rabbit model, 9THC showed improved penetration to the anterior chamber with reduction of intraocular pressure using a prodrug. THC is an established neuroprotectant and has the possibility of being an effective IOP lowering agent. THC and THC-Val-HS reached the retina choroid(5).

 

In one study of 32 different types of cannabinoids, it was found that certain derivatives of delta 9THC and delta 8THC were more effective at lowering intraocular pressure in glaucoma than the parent derivative cannabidiol (1).

37608_434614963840_3006668_n

 

Introduction/Disclaimer

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References

  1. 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.
  2. Jarvinen, T., “Cannabinoids in treatment of glaucoma,” 2002, Aug., 95(2):203-20.
  3.  Karanian, et al, “Cannabinoid drugs and enhancement of endocannabinoid responses: strategies for a wide array of disease states,” Current Molecular Med., 2006, Sep., 6(6):677-84.
  4.  Rapino, et al, “Neuroprotection by endocannabinoids in glaucoma and retinal neurodegenerative diseases,” Current Neuropharmacology, 2017, Jul., doi:10.2174 (Epub ahead of print)
  5.  Goutham, et al, ” Development of a 9tetrahydrocannabidiol amino acid dicarboxylate prodrug with improved ocular bioavailablity,” Investigative Ophthalmology and Visual Science, 2017, Apr., 58(4):2167-2179.

 

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Epilepsy, Uncategorized

Dravet syndrome: clinical course, SCN1A genetic abnormality involved and non-pharmacologic options including ketogenic diet and cannabidiol

By: Virginia Thornley, M.D., Epileptologist, General Neurologist

February 20, 2018

Dravet first described the syndrome that now bears his name in 1978. It is now a model for some of the channelopathies seen manifesting as epilepsy.

Clinical course and electroencephalographic manifestations

Dravet syndrome is also known as the severe myoclonic epilepsy in infancy (SMEI). Patients usually have no delay in development prior to the first seizure. It usually starts between 5-8 months of life another report mentions after 2nd year of life and may follow a febrile seizure. It consists of generalized tonic-clonic seizures and myoclonus. The term severe myocolic epilepsy of infancy (SMEI) is a misnomer as some patients with this gene related disorder may not manifest with myoclonus so Dravet syndrome is preferred. Clinical evolution includes an initial presentation of generalized tonic-clonic seizures evolving into multiple seizure types predominantly myoclonus. Complex partial seizures, focal seizures, and atypical absence seizures may be identified. Myoclonus is seen about 2 years of age and eventually disappears. The generalized type of seizures persists into adulthood. The EEG background becomes progressively slower, with poor organization. There is the presence of excessive frontal theta rhythms and discharges consist of spike, spike and wave and polyspike and wave complexes. There is sensitivity to fevers. It is usually associated with cognitive impairment. Lifespan is unclear as case series are not reported on those after 20 years of age (1).

SCN1A gene

Dravet syndrome is found to be one of the SCN1A-related disorders causing seizures. Genetic testing reveals a heterozygous variant of SCN1A. SCN1A encodes Nav1.1 or the alpha subunit of the voltage-gated sodium channel. Seizures related to this channel are channelopathies. Due to the molecular abnormality at the level of the channel, there is hyperexcitability due to the imbalance of excitation versus inhibition because of neuronal dysfunction at the level of the sodium channel. The SCN1A is encoded on chromosome 2q24 which also includes SCN2A and SCN3A. In epilepsy-associated variants which are all found in the Nav1.1 alpha subunit, they are more frequently found in the C-terminus, and some in the N-terminus. In Dravet syndrome, nearly 50% are truncating variants, while others are splice, missense or deletion types of abnormalities.  The pathophysiology is an area under intense investigation but likely due to loss of the excitability of inhibitory function of the GABAergic pathway causing seizures(4).

Non-pharmacologic ways to deal with conditions of Dravet syndrome

Anti-convulsants to avoid

Prescription agents are not discussed as new agents become available year to year. However, there are medications that should be avoided including carbamazepine, lamotrigine, vigabatrin, and phenytoin. Rufinamide is a similar agent to carbamazepine and could theoretically worsen this condition. Sodium channel blockers like these worsen these types of seizure. In Dravet syndrome,  there is an abnormality of voltage-gated sodium channel Nav1.1, where one would think there would be fewer seizures following the thinking that sodium channel blockers are used anticonvulsants. However, with the sodium channel abnormality in SCN1A seizure disorders, there is more inhibition of the GABAergic pathway which keeps seizures in check thus, there are more excitatory neurotransmitters available causing seizures to occur(4).

Ketogenic diet and mechanisms of action

The ketogenic diet has been found to improve the condition. With ketogenesis, instead of glucose being used as a substrate for seizures, there are increased ketones available from a high fatty acid diet in the body meaning less available glucose that helps keep up the metabolism required with energy expenditure used in seizures. The body uses ketones as the fuel source. Ketogenesis occurs with natural fasting when the body breaks down fat through lipolysis. Then, the fatty acids produced undergo beta-oxidation into ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone) which are used to produce energy ATP (adenosine triphosphate) used by the cells(3). The ketogenic diet mimics this natural process by using a high fat low carbohydrate diet so that instead of glucose the body uses fatty acids which turn into ketones used as a fuel source which is not conducive to seizures.  With ketogenic diet as a therapeutic option, it is key to see a dietician as the diet is strictly high fat. It is based on a tightly regimented all or none principle otherwise it will not work. Most patients eventually find the diet highly unpalatable and may give up. However, if followed faithfully, it may be a viable non-pharmacologic additional option in medically refractory patients with seizures. One study found a 62% reduction rate in Dravet syndrome using the ketogenic diet(2). In the study, the EEG significantly improved and a favorable outcome was seen in those with a shorter duration of the condition and those with generalized tonic-clonic seizures. However, like most studies of rare diseases the number studied was small.

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Other mechanisms proposed include changing the pH of the brain making it less favorable for the production of seizures, direct inhibition of ion channels by ketone bodies, and changes in amino acid metabolism to favoring GABAergic synthesis which is inhibitory to seizures.

Cannabidiol in Dravet syndrome

One study examining the effects of cannabidiol (CBD) on Dravet syndrome postulate mechanisms including increasing excitation of the inhibitory effect of the hippocampus where seizures are propagated.  At low doses, it helps with autism and impaired cognition.  It may exert its effect by working against GPR55. The effects of CBD on neurotransmitters were similar to the GPR55 antagonist suggesting CBD works at the level of this lipid-activating G-protein coupled receptor(5).

Consult with your neurologist.

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References

1. Akiyama, et al, “Dravet Syndrome: A Genetic Epileptic Disorder,”Acta Med. Okayama, 2012, 66(5):369-376.

2. Dressler, et al, “Long-term outcome and tolerability of ketogenic diet in childhood epilepsy— the Austrian experience,”Seizure, 2010, Sept., 19(17):404-408.

3. Maranano, et al, “The ketogenic diet: uses in seizures and other neurologic illness,” Current Treatment Options in Neurology, 2008, Nov., 10(6)410-419.

4. Miller, et al, “SCN1A-Related Seizure Disorder,” Gene Reviews, 2007, Nov., Updated 2014, May.

5. 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.

 

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