One of the complications I face with clinical practice in Florida is that for the past couple of years, the state has allowed the use of so called Medical Marijuana and Cannabis. Since the law went into effect, dispensaries have cropped up in every city and town and I am informed by a patient that acquiring a prescription for MM from an MD affiliated with a dispensary is as easy as showing up and signing a few forms. None of my patients who have been prescribed MM had a physical exam by the dispensing physician and there is no follow up unless the patient requests one. The non medical dispensary operators are given carte blanche to suggest dosage and delivery mechanisms and some patients who have expressed concerns about addiction and other negative side effects have been told that MM “works for everyone” and that there are “absolutely no negative side effects, ever”.
Because marijuana is currently classified by the US federal government as Schedule I, “a drug with no medical use”, studies that discuss medical marijuana are limited in both number and scope. Many studies compare smoking habits and respiratory distress among cigarette and cannabis smokers, as well as symptoms of abuse and addiction in recreational users, but few address the side effects of medical marijuana.
One study in Canada described the most common side effects of cannabis use in patients with non-chronic cancer pain as “cognitive side effects” and dry mouth. In the United States, nabilone may produce similar “cognitive side effects” or psychiatric symptoms, hypo and hypertension, and tachycardia if the prescribed dosage is too high. Dronabinol has also been associated with a “cognitive side effects,” sleepiness, or withdrawal symptoms lasting up to 48 hours that appeared in only one study, which promptly stopped dispensing the medication. The categorization of cannabis as Schedule I, therefore, is a double-edged sword: because few clinical trials have been run, few negative side effects have been reported.
Effect of cannabis use in people with chronic non-cancer pain prescribed opioids: findings from a 4-year prospective cohort study
~ The Lancet, British Medical Journal, July 2018
In conclusion, cannabis use is common in people with chronic non-cancer pain who have been prescribed opioids, and interest in medicinal use of cannabis is increasing. We found no evidence that cannabis use improved patient outcomes; those who used cannabis had greater pain and lower self-efficacy in managing pain. Furthermore, we found no evidence that cannabis use reduced pain interference or exerted an opioid-sparing effect. ~
Medical marijuana: Do the benefits outweigh the risks?
~ Current Psychiatry · January 2018
There is no clear and convincing evidence MM is beneficial for psychiatric disorders, and Cannabis can impair cognition and attention and may precipitate psychosis. The risks of deleterious effects are greater in adolescents. Cannabis use causes impairment of learning, memory, attention, and working memory. Adolescents are particularly vulnerable to the effects of Cannabis on brain development at a time when synaptic pruning and increased myelination occur. Normal brain development could be disrupted. Some studies have linked Cannabis use to abnormalities in the amygdala, hippocampus, frontal lobe, and cerebellum. From 1995 to 2014, the potency of Cannabis (THC concentration) increased from 4% to 12%.58 this has substantial implications for increased abuse among adolescents and the deleterious effects of Cannabis on the brain.
Heavy Cannabis use impairs motivation and could precipitate psychosis in vulnerable individuals. Cannabis use may be linked to the development of schizophrenia.59
There are no well-conducted Randomized Controlled Trails on the efficacy of MM, and adequate safety data are lacking. There is also lack of consensus among qualified experts. There is soft evidence that MM may be helpful in some medical conditions, including but not limited to CINV, neuropathic pain, epilepsy, and MS-related spasticity. Currently, the benefits of using MM do not appear to outweigh the risks. ~
Cannabis for Chronic Pain: Not Ready for Prime Time
~ American Journal of Public Health January 2019
The use of cannabis (particularly its principal psychoactive constituent, Δ tetrahydrocannabinol or THC) is associated with health risks including lung disease (when smoked), cardiovascular disease, acute pancreatitis, and cannabinoid hyperemesis syndrome. Cannabis users are also at increased risk for occupational injuries, and cannabis-associated “drugged driving”, sometimes fatal, is increasing. Cannabis use during pregnancy has been associated with increased neonatal morbidity or death.Finally, the myth that marijuana is non-addictive has been dispelled by studies of forced abrupt cessation of use indicating potential rebound hyperalgesia and craving. As the health risks associated with cannabis come under increasing scrutiny.
Diminution of gray matter in the brain in chronic cannabis users has long been recognized. Empirically established deficits following months to years of use involve—but are not limited to—executive functioning, information retrieval, learning, abstraction, motor skills, and verbal abilities, with use of higher-THC cannabis resulting in more profound deficits. Psychopathological consequences of cannabis use include acute psychosis, schizophrenia, worsened social functioning in schizophrenia, bipolar disorder, depression, and anxiety (particularly with increasingly common high-sativa content strains).
Objective data on the efficacy of cannabis for pain management are not particularly encouraging.Cannabis can be helpful in relieving neuropathic pain, with the magnitude of analgesia generally contingent on the amount of THC. Unfortunately, higher-THC cannabis, similar to opioids, also produces more cognitive side effects, often rendering patients impaired at work and in activities of daily living. Moreover, much of the earlier clinical trial literature on cannabis for neuropathic pain has been rendered obsolete.
Unfortunately, it remains extremely difficult to conduct clinically relevant medical cannabis research in the United States because of the drug’s Schedule I status, and the requirement that all cannabis used be obtained from a single farm at the University of Mississippi, and it is permitted to grow only 1000 pounds of cannabis for research purposes each year. Even more problematic is that until very recently, the University of Mississippi was permitted to cultivate cannabis with a maximum THC content of 7%, yet 67% of medical cannabis consumers choose to use oils and other concentrates with THC contents as high as 90%. Cannabis for investigation with a higher THC content (13.4%) was obtainable only recently from the National Institute on Drug Abuse (NIDA). Thus, research on the analgesic efficacy of what the DEA considers “strong marijuana” has been flawed.
Adding to these reservations concerning cannabis as an analgesic is that THC is not the most medically relevant constituent of cannabis. Cannabidiol (CBD) is a noneuphoriant cannabinoid with a good safety profile and has activity as both an analgesic and anti-inflammatory. Importantly, CBD modulates the euphoria produced by THC and provides mild anxiolysis. Although it is thought that cannabis contained equal amounts of THC and CBD in pre-agricultural times, when the plant grew wild, users’ and hence growers’ desire to maximize THC content for its euphoric effects has resulted in CBD being all but bred out of the vast majority of cultivated cannabis. Efforts to find cannabis that contains low concentrations of THC and high levels of CBD in dispensaries are often futile. Furthermore, the CBD that is found in common hemp (the most widely used source for commercial non medical CBD oil) is virtually nonexistent.
Few if any health care providers who authorize medical cannabis educate their patients specifically to seek the most “medicinal” forms of the drug. Even if this aspect of sourcing a uniform, well-characterized supply of cannabis for research or clinical purposes were overcome, another fundamental challenge for such studies is that (unlike for morphine or other opioids) blood levels of these agents do not consistently correlate with their in vivo effects. ~
In the last Blog we learned that traditional Chinese medicine and Chinese medical psychiatry do not condone the use of the use of medical cannabis or marijuana for indications of pain management, addiction withdrawal, constipation and lack of appetite does not advise its use given the historical understanding and the negative side effects involved.
In the light of the unsettling safety profile of cannabis, the lack of strong empirical support for its efficacy, the general absence of CBD in what is used “medically,” and the methodological challenges in conducting research suggest that, at present, cannabis should not necessarily be considered an optimal choice as a drug for pain management.
Next time I will explore the future of medicinal marijuana and cannabis and its probable effect on health and society.
Yours in good health,
Robert Kienitz, DTCM