Ethics
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.
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.
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. The ethics around cannabis research is in a state of rapid change.
Research by region
United States
Research
on the medical benefits of cannabis has been hindered by various
federal regulations, including its Schedule I classification. To conduct research on cannabis, approval must be obtained from the Food and Drug Administration, and a license must be obtained from the Drug Enforcement Administration specific to Schedule I drugs. The FDA has 30 days to respond to proposals, while the DEA licensing can take over a year to complete. Prior to June 2015, cannabis research also required approval from the US Public Health Service. The PHS review was not performed for any other Schedule I drugs, and had no deadline imposed.
In addition to the FDA and DEA (and former PHS) requirements, the National Institute on Drug Abuse must review and approve all cannabis research.
The NIDA is the only source licensed by the federal government for the
cultivation and provision of cannabis, and the NIDA will not provide
cannabis without first approving the research. This monopoly maintained by the DEA does not exist for other Schedule I drugs, and there is no deadline established for the NIDA review either. The quality and potency of cannabis supplied by NIDA has also been called into question by some researchers.
As a result of these requirements that have been imposed in the
US, studies involving cannabis have been delayed for years in some
cases, and a number of medical organizations have called for federal policy to be reformed.
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.
In April 2018, after 5 years of research, Sanjay Gupta backed medical marijuana for conditions such as epilepsy and multiple sclerosis. He believes that medical marijuana is safer than opioid for pain management.
Research by medical condition
Cancer
Cannabinoids
have been shown to exhibit some anti-cancer effects in laboratory
experiments, although there has been little research into their use as a
cancer treatment in people. Laboratory experiments have suggested that cannabis and cannabinoids have anticarcinogenic and antitumor effects, including a potential effect on breast- and lung-cancer cells. The National Cancer Institute reports that as of November 2013 there have been no clinical trials on the use of cannabis to treat cancer in people, and only one small study using delta-9-THC that reported potential antitumoral activity.
While cannabis may have potential for refractory cancer pain, use as an
antiemetic, and as an antitumor agent, much of the evidence comes from
outdated or small studies, or animal experiments.
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".
There is no good evidence that cannabis use helps reduce the risk of getting cancer.
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. Cannabis use is linked to an increased risk of a type of testicular cancer.
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.
Dementia
Cannabinoids have been proposed to have the potential for lessening the effects of Alzheimer's disease.
A 2012 review of the effect of cannabinoids on brain ageing found that
"clinical evidence regarding their efficacy as therapeutic tools is
either inconclusive or still missing". A 2009 Cochrane review
said that the "one small randomized controlled trial [that] assessed
the efficacy of cannabinoids in the treatment of dementia ... [had] ...
poorly presented results and did not provide sufficient data to draw any
useful conclusions".
Diabetes
There is emerging evidence that cannabidiol may help slow cell damage in diabetes mellitus type 1.
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".
Epilepsy
A 2016 review in the New 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". The mechanisms by which cannabis may be effective in the treatment of epilepsy remain unclear.
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
– 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).
Epidiolex, a cannabis-based product developed by GW Pharmaceuticals for experimental treatment of epilepsy, underwent stage-two trials in the US in 2014.
A 2017 study found that cannabidiol decreased the rate of seizures in those with Dravet syndrome but increased the rate of sleepiness and trouble with the liver.
Glaucoma
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". As of 2008 relatively little research had been done concerning therapeutic effects of cannabinoids on the eyes.
Tourette syndrome
A 2007 review of the history of medical cannabis said cannabinoids showed potential therapeutic value in treating Tourette syndrome (TS). 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; a 2000 review said other studies had shown that cannabis "has no effects on tics and increases the individuals inner tension".
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).
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". The sample size was small and a high number of individuals either dropped out of the study or were excluded.
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. The authors of the original studies acknowledged few significant results after Bonferroni correction.
Cannabinoid medication might be useful in the treatment of the symptoms in patients with TS, but the 2009 review found that the two relevant studies of cannibinoids in treating tics had attrition bias,
and that there was "not enough evidence to support the use of
cannabinoids in treating tics and obsessive compulsive behaviour in
people with Tourette's syndrome".
Other conditions
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. 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.
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.
Cannabinoids have been proposed for the treatment of primary anorexia nervosa, but have no measurable beneficial effect. The authors of a 2003 paper argued that cannabinoids might have useful future clinical applications in treating digestive diseases. Laboratory experiments have shown that cannabinoids found in marijuana may have analgesic and anti-inflammatory effects.
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.
Cannabis is being investigated for its possible use in inflammatory bowel disease but as of 2014 there is only weak evidence for its benefits as a treatment.
A 2007 review said cannabidiol had shown potential to relieve convulsion, inflammation, cough, congestion and nausea, and to inhibit cancer cell growth. Preliminary studies have also shown potential over psychiatric conditions such as anxiety, depression, and psychosis. Because cannabidiol relieves the aforementioned symptoms, cannabis strains with a high amount of CBD may benefit people with multiple sclerosis or frequent anxiety attacks.
