Medical cannabis research includes any medical research on using cannabis. The earliest systematic studies of physiological effects of cannabis-derived chemical were conducted in the 1920's (see Fig. The number of publications about marijuana/cannabis). The level or research activity in this area remained relatively low and constant until 1966, when a 10-fold increase in publication activity occurred within 10 years. After the adoption of the Convention on Psychotropic Substances in 1971 there was a drop in research publishing, which continued till ca. 1987. Since then, cannabis research has been continuously on the rise. There is no apparent inflection point is 2013, when Uruguay "became the first country in the world to fully regulate its marijuana market, from production to consumption and distribution." [1] Since then a large number of countries enacted policies on medical cannabis research, and there are substantial differences between such policies in different countries.
Cannabis use as a medical treatment has risen globally since 2008 for a variety of reasons including increasing popular support for cannabis legalization and increased incidence of chronic pain among patients. [2] While medical cannabis use is increasing, there are major social and legal barriers which lead to cannabis research proceeding more slowly and differently from standard medical research. [2] Reasons why cannabis is unusual as a treatment include that it is not a patented drug owned by the pharmaceutical industry, and that its legal status as a medical treatment is ambiguous even where it is legal to use, and that cannabis use carries outside the norm of a typical medical treatment. [2] The ethics around cannabis research is in a state of rapid change. [2]
Research on the medical benefits of cannabis has been hindered by various federal regulations, including its Schedule I classification. [3] To conduct research on cannabis, approval must be obtained from the Food and Drug Administration, [4] and a license must be obtained from the Drug Enforcement Administration specific to Schedule I drugs. [5] The FDA has 30 days to respond to proposals, [6] while the DEA licensing can take over a year to complete. [7] Prior to June 2015, cannabis research also required approval from the US Public Health Service. [8] The PHS review was not performed for any other Schedule I drugs, and had no deadline imposed. [6]
In addition to the FDA and DEA (and former PHS) requirements, the National Institute on Drug Abuse was required to review and approve all research on cannabis prior to 2021. [9] NIDA was the only source licensed by the federal government for the cultivation and provision of cannabis, and NIDA would not provide cannabis without first approving the research. [4] This monopoly maintained by the DEA did not exist for other Schedule I drugs, [3] and there was no deadline established for the NIDA review either. [6] The quality and potency of cannabis supplied by NIDA has also been called into question by some researchers. [10] [11] In 2021 the DEA granted additional licenses for the cultivation of cannabis, however, [12] [13] after first announcing intention to do so in 2016. [14]
As a result of these requirements that have been imposed in the US, studies involving cannabis have been delayed for years in some cases, [4] [8] and a number of medical organizations have called for federal policy to be reformed. [15] [16] [17] [7]
A 2016 review assess the current status and prospects for development of CBD and CBD-dominant preparations for medical use in the United States, examining its neuroprotective, antiepileptic, anxiolytic, antipsychotic, and antiinflammatory properties. [18]
In April 2018, after 5 years of research, Sanjay Gupta backed medical marijuana for conditions such as epilepsy and multiple sclerosis. [19] He believes that medical marijuana is safer than opioid for pain management. [20] [21]
Laboratory experiments have suggested that cannabis and cannabinoids have anticarcinogenic and antitumor effects, [22] including a potential effect on breast- and lung-cancer cells. [23] While cannabis may have potential for refractory cancer pain or use as an antiemetic, much of the evidence comes from outdated or small studies, or animal experiments. [24]
Although there is ongoing research, claims that cannabis has been proved to cure cancer are, according to Cancer Research UK, both prevalent on the internet and "highly misleading". [25]
There is no good evidence that cannabis use helps reduce the risk of getting cancer. [25] Whether smoking cannabis increases cancer risk in general is difficult to establish since it is often smoked mixed with tobacco –a known carcinogen –and this complicates research. [25] Cannabis use is linked to an increased risk of a type of testicular cancer. [26]
The association of cannabis use with head and neck carcinoma may differ by tumor site, with both possible pro- and anticarcinogenic effects of cannabinoids. Additional work is needed to rule out various sources of bias, confounds and misclassification of cannabis exposure. [27]
Medical cannabis has been studied for its potential in treating dementia and dementia-related conditions but as of 2019 [update] evidence of its usefulness remains weak. [28]
From weak evidence it appears cannabis use has little effect on the risk of developing type 2 diabetes, possibly slightly reducing it. [29]
There is emerging evidence that cannabidiol may help slow cell damage in diabetes mellitus type 1. [30] There is a lack of meaningful evidence of the effects of medical cannabis use on people with diabetes; a 2010 review concluded that "the potential risks and benefits for diabetic patients remain unquantified at the present time". [31]
Cannabidiol (CBD) epilepsy treatments go as far back as 1800 BC. Cannabis therapy and research diminished with prohibition laws in the US. However, in 1980 a double-blind study by JM Cunha and his team renewed the interest in cannabis treatments when the data showed improvements of patients who had taken CBD oil. In 2003 and 2004 numerable sporadic reports led by German analysts also demonstrated the success of cannabis treatments with children that had severe neurological disorders. A 2016 review in TheNew England Journal of Medicine said that although there was a lot of hype and anecdotes surrounding medical cannabis and epilepsy, "current data from studies in humans are extremely limited, and no conclusions can be drawn". [32] The mechanisms by which cannabis may be effective in the treatment of epilepsy remain unclear. [33]
Some reasons for the lack of clinical research have been the introduction of new synthetic and more stable pharmaceutical anticonvulsants, the recognition of important adverse side effects, and legal restrictions to the use of cannabis-derived medicines [34] – although in December 2015, the DEA (United States Drug Enforcement Administration) has eased some of the regulatory requirements for conducting FDA-approved clinical trials on cannabidiol (CBD). [35]
Epidiolex, a cannabis-based product developed by GW Pharmaceuticals for experimental treatment of epilepsy, underwent stage-two trials in the US in 2014. [36]
In 2009, the American Glaucoma Society noted that while cannabis can help lower intraocular pressure, it recommended against its use because of "its side effects and short duration of action, coupled with a lack of evidence that its use alters the course of glaucoma". [37] As of 2008 relatively little research had been done concerning therapeutic effects of cannabinoids on the eyes. [38]
A 2007 review of the history of medical cannabis said cannabinoids showed potential therapeutic value in treating Tourette syndrome (TS). [39] A 2005 review said that controlled research on treating TS with dronabinol showed the patients taking the pill had a beneficial response without serious adverse effects; [40] a 2000 review said other studies had shown that cannabis "has no effects on tics and increases the individuals inner tension". [41]
A 2009 Cochrane review examined the two controlled trials to date using cannabinoids of any preparation type for the treatment of tics or TS (Muller-Vahl 2002, and Muller-Vahl 2003). Both trials compared delta-9-THC; 28 patients were included in the two studies (8 individuals participated in both studies). [42] Both studies reported a positive effect on tics, but "the improvements in tic frequency and severity were small and were only detected by some of the outcome measures". [42] The sample size was small and a high number of individuals either dropped out of the study or were excluded. [42] The original Muller-Vahl studies reported individuals who remained in the study; patients may drop out when adverse effects are too high or efficacy is not evident. [42] The authors of the original studies acknowledged few significant results after Bonferroni correction. [42]
Cannabinoid medication might be useful in the treatment of the symptoms in patients with TS, [42] but the 2009 review found that the two relevant studies of cannabinoids in treating tics had attrition bias, and that there was "not enough evidence to support the use of cannabinoids in treating tics [or] obsessive [and] compulsive behaviour[s] in people with Tourette's syndrome". [42]
Anecdotal evidence and pre-clinical research has suggested that cannabis or cannabinoids may be beneficial for treating Huntington's disease or Parkinson's disease, but follow-up studies of people with these conditions have not produced good evidence of therapeutic potential. [43] A 2001 paper argued that cannabis had properties that made it potentially applicable to the treatment of amyotrophic lateral sclerosis, and on that basis research on this topic should be permitted, despite the legal difficulties of the time. [44]
A 2005 review and meta-analysis said that bipolar disorder was not well-controlled by existing medications and that there were "good pharmacological reasons" for thinking cannabis had therapeutic potential, making it a good candidate for further study. [45]
Cannabinoids have been proposed for the treatment of primary anorexia nervosa, but have no measurable beneficial effect. [46] The authors of a 2003 paper argued that cannabinoids might have useful future clinical applications in treating digestive diseases. [47] Laboratory experiments have shown that cannabinoids found in marijuana may have analgesic and anti-inflammatory effects. [23]
In 2014, the American Academy of Neurology reviewed all available findings levering the use of marijuana to treat brain diseases. The result was that the scientific evidence is weak that cannabis in any form serves as medicinal for curing or alleviating neurological disorders. To ease multiple sclerosis patients' stiffness, which may be accomplished by their taking cannabis extract by mouth or as a spray, there is support. The academy has published new guidelines on the use of marijuana pills and sprays in the treatment of MS. [48]
Cannabis is being investigated for its possible use in inflammatory bowel disease but as of 2014 [update] there is only weak evidence for its benefits as a treatment. [49]
A 2007 review said cannabidiol had shown potential to relieve convulsion, inflammation, cough, congestion and nausea, and to inhibit cancer cell growth. [50] Preliminary studies have also shown potential over psychiatric conditions such as anxiety, depression, and psychosis. [51] Because cannabidiol relieves the aforementioned symptoms, cannabis strains with a high amount of CBD may benefit people with multiple sclerosis or frequent anxiety attacks. [52] [50]
Canadian researchers are currently studying a strain of cannabis as a potential COVID-19 treatment. [53]
Tetrahydrocannabinol (THC) is a cannabinoid found in cannabis. It is the principal psychoactive constituent of cannabis and one of at least 113 total cannabinoids identified on the plant. Although the chemical formula for THC (C21H30O2) describes multiple isomers, the term THC usually refers to the delta-9-THC isomer with chemical name (−)-trans-Δ9-tetrahydrocannabinol. It is a colorless oil.
The effects of cannabis are caused by chemical compounds in the cannabis plant, including 113 different cannabinoids such as tetrahydrocannabinol (THC) and 120 terpenes, which allow its drug to have various psychological and physiological effects on the human body. Different plants of the genus Cannabis contain different and often unpredictable concentrations of THC and other cannabinoids and hundreds of other molecules that have a pharmacological effect, so the final net effect cannot reliably be foreseen.
Medical cannabis, medicinal cannabis or medical marijuana (MMJ), is cannabis and cannabinoids that are prescribed by physicians for their patients. The use of cannabis as medicine has not been rigorously tested due to production and governmental restrictions, resulting in limited clinical research to define the safety and efficacy of using cannabis to treat diseases.
Cannabinoids are several structural classes of compounds found in the cannabis plant primarily and most animal organisms or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tetrahydrocannabinol (THC) (delta-9-THC), the primary psychoactive compound in cannabis. Cannabidiol (CBD) is also a major constituent of temperate cannabis plants and a minor constituent in tropical varieties. At least 113 distinct phytocannabinoids have been isolated from cannabis, although only four have been demonstrated to have a biogenetic origin. It was reported in 2020 that phytocannabinoids can be found in other plants such as rhododendron, licorice and liverwort, and earlier in Echinacea.
Cannabinol (CBN) is a mildly psychoactive cannabinoid (e.g., cannabidiol (CBD)) that acts as a low affinity partial agonist at both CB1 and CB2 receptors. This activity at CB1 and CB2 receptors constitutes interaction of CBN with the endocannabinoid system (ECS).
Cannabidiol (CBD) is a phytocannabinoid discovered in 1940. It is one of 113 identified cannabinoids in cannabis plants, along with tetrahydrocannabinol (THC), and accounts for up to 40% of the plant's extract. As of 2022, clinical research on CBD included studies related to the treatment of anxiety, addiction, psychosis, movement disorders, and pain, but there is insufficient high-quality evidence that cannabidiol is effective for these conditions. CBD is also sold as a herbal dietary supplement promoted with unproven claims of particular therapeutic effects.
Tetrahydrocannabivarin is a homologue of tetrahydrocannabinol (THC) having a propyl (3-carbon) side chain instead of pentyl (5-carbon), making it non-psychoactive in lower doses. It has been shown to exhibit neuroprotective activity, appetite suppression, glycemic control and reduced side effects compared to THC, making it a potential treatment for management of obesity and diabetes. THCV was studied by Roger Adams as early as 1942.
In the United States, the removal of cannabis from Schedule I of the Controlled Substances Act, the category reserved for drugs that have "no currently accepted medical use", is a proposed legal and administrative change in cannabis-related law at the federal level. After being proposed repeatedly since 1972, the U.S. Department of Justice initiated 2024 rulemaking to reschedule cannabis to Schedule III of the Controlled Substances Act. The majority of 2024 public comments supported descheduling, decriminalizing, or legalizing marijuana at the federal level.
Cannabis, also known as marijuana or weed, among other names, is a non-chemically uniform drug from the cannabis plant. Native to Central or South Asia, the cannabis plant has been used as a drug for both recreational and entheogenic purposes and in various traditional medicines for centuries. Tetrahydrocannabinol (THC) is the main psychoactive component of cannabis, which is one of the 483 known compounds in the plant, including at least 65 other cannabinoids, such as cannabidiol (CBD). Cannabis can be used by smoking, vaporizing, within food, or as an extract.
Nabilone, sold under the brand name Cesamet among others, is a synthetic cannabinoid with therapeutic use as an antiemetic and as an adjunct analgesic for neuropathic pain. It mimics tetrahydrocannabinol (THC), the primary psychoactive compound found naturally occurring in Cannabis.
Nabiximols is a specific Cannabis extract that was approved in 2010 as a botanical drug in the United Kingdom. Nabiximols is sold as a mouth spray intended to alleviate neuropathic pain, spasticity, overactive bladder, and other symptoms of multiple sclerosis; it was developed by the UK company GW Pharmaceuticals. In 2019, it was proposed that following application of the spray, nabiximols is washed away from the oral mucosa by the saliva flow and ingested into the stomach, with subsequent absorption from the gastro-intestinal tract. Nabiximols is a combination drug standardized in composition, formulation, and dose. Its principal active components are the cannabinoids: tetrahydrocannabinol (THC) and cannabidiol (CBD). Each spray delivers a dose of 2.7 mg THC and 2.5 mg CBD.
Cannabis tea is a cannabis-infused drink prepared by steeping various parts of the cannabis plant in hot or cold water. Cannabis tea is commonly recognized as an alternative form of preparation and consumption of the cannabis plant, more popularly known as marijuana, pot, or weed. This plant has long been recognized as an herbal medicine employed by health professionals worldwide to ease symptoms of disease, as well as a psychoactive drug used recreationally and in spiritual traditions. Though less commonly practiced than popular methods like smoking or consuming edibles, drinking cannabis tea can produce comparable physical and mental therapeutic effects. Such effects are largely attributed to the THC and CBD content of the tea, levels of which are drastically dependent on individual preparation techniques involving volume, amount of cannabis, and boiling time. Also in common with these administration forms of cannabis is the heating component performed before usage. Due to the rather uncommon nature of this particular practice of cannabis consumption in modern times as well as the legality of cannabis throughout the World, the research available on the composition of cannabis tea is limited and based broadly around what is known of cannabis as it exists botanically.
Geoffrey William Guy is a British pharmacologist, physician, businessman and academic, who co-founded GW Pharmaceuticals and has developed treatments using compounds found in cannabis, which are the first cannabis-based medicines approved by and available on the British National Health Service (NHS).
Cannabis strains is a popular name to refer to plant varieties of the monospecific genus Cannabis sativa L.. They are either pure or hybrid varieties of the plant, which encompasses various sub-species C. sativa, C. indica, and C. ruderalis.
In the United States, the use of cannabis for medical purposes is legal in 38 states, four out of five permanently inhabited U.S. territories, and the District of Columbia, as of March 2023. Ten other states have more restrictive laws limiting THC content, for the purpose of allowing access to products that are rich in cannabidiol (CBD), a non-psychoactive component of cannabis. There is significant variation in medical cannabis laws from state to state, including how it is produced and distributed, how it can be consumed, and what medical conditions it can be used for.
Dronabinol, also known under the brand names Marinol and Syndros, is a generic name for the molecule of delta-9-tetrahydrocannabinol in the pharmaceutical context. It has indications as an appetite stimulant, antiemetic, and sleep apnea reliever and is approved by the FDA as safe and effective for HIV/AIDS-induced anorexia and chemotherapy-induced nausea and vomiting only.
The long-term effects of cannabis have been the subject of ongoing debate. Given that the use of cannabis is illegal in most countries, clinical research presents a challenge and there is limited evidence from which to draw conclusions. In 2017, the U.S. National Academies of Sciences, Engineering, and Medicine issued a report summarizing much of the published literature on health effects of cannabis, into categories regarded as conclusive, substantial, moderate, limited and of no or insufficient evidence to support an association with a particular outcome.
GW Pharmaceuticals Limited is a British pharmaceutics company known for its multiple sclerosis treatment product nabiximols which was the first natural cannabis plant derivative to gain market approval in any country. Another cannabis-based product, Epidiolex, was approved for treatment of epilepsy by the US Food and Drug Administration in 2018. It is a subsidiary of Jazz Pharmaceuticals.
Charlotte's Web is a brand of high-cannabidiol (CBD), low-tetrahydrocannabinol (THC) products derived from industrial hemp and marketed as dietary supplements and cosmetics under federal law of the United States. It is produced by Charlotte's Web, Inc. in Colorado. Hemp-derived products do not induce the psychoactive "high" typically associated with recreational marijuana strains that are high in THC. Charlotte's Web hemp-derived products contain less than 0.3% THC.
The Cannabinoid Research Initiative of Saskatchewan (CRIS) was founded in 2017 as an interdisciplinary research team of clinician researchers (medical and veterinary), basic scientists, and social scientists. CRIS aims to obtain scientific evidence about the application of Cannabinoids and Medical cannabis to humans and animals, for health, disease and disorders. The team was initially based at the University of Saskatchewan, in Saskatoon, Saskatchewan, Canada but includes researchers based at the University of Regina and University of Alberta. A strategic management executive committee coordinates activities and develops research opportunities. The sections of CRIS include: Analytical Evaluations, Human Clinical Studies, Biomedical studies, Veterinary Sciences, Knowledge Translation and Studies of Cannabinoids and Society. CRIS members participate in the Canadian Consortium for the Investigation of Cannabinoids, and the International Cannabinoid Research Society.
{{cite journal}}
: CS1 maint: multiple names: authors list (link)