by Dr. Al Al-Alhaidari
Cannabis as a Medicine
The use of cannabis as a medical agent has a long history in both folk and professional medicine (Kalant, 2001). Its modern era began in the mid-19th century, when O’Shaughnessy (1843) described the use of crude cannabis preparations in India for the treatment of muscle spasms and convulsions. Later observations recorded its use in Indian folk medicine for the relief of a wide variety of disease symptoms, including pain, diarrhea, fever, anxiety, sleeplessness and lack of appetite (Kalant, 1972). O’Shaughnessy sent samples of Indian cannabis to London, where they were analyzed and used to prepare standardized extracts that were incorporated into the British and American pharmacopoeias of recognized drugs and medicinal preparations, leading to the wide use of cannabis in medical practice in many parts of the world.
In the 20th century, however, the medical use of cannabis gradually decreased because of its unreliability, which resulted from the variable composition of the extracts and their limited shelf life. Cannabis was largely replaced by purified single drugs, both natural and synthetic, with more reliable potency and stability. For example, a variety of natural and synthetic opium-like drugs replaced cannabis as pain relievers, and barbiturates replaced cannabis as sleep-inducers and anti-convulsants. When cannabis was made illegal in many countries between the years 1923 and 1952, this move provoked relatively little opposition because the drug had largely fallen out of use by that time.
The revival of interest in cannabis in Western countries in the 1960s was related principally to its nonmedical use by young people to produce euphoria and facilitate social interaction (the “high”). However, as scientific interest revived, the exploration of its potential therapeutic uses was renewed, and has increased greatly since the discovery of the endocannabinoid system and its widespread physiological activity in many different body organs and tissues, described later in this report.
Uses of Cannabis and Cannabinoids as Medicine
(a) Nausea and vomiting
In many countries, including Canada, cannabis and individual cannabinoids are approved for relief and prevention of nausea and vomiting caused by anti-cancer and anti-HIV chemotherapy. This action is exerted through the endocannabinoid system , and might be effective against nausea due to some other causes, such as diffuse cancer .
(b) Appetite stimulation
Cannabis and cannabinoids are also approved for stimulation of appetite in AIDS patients with a severe loss of body weight. However this action, exerted through CB1 receptors, mainly increases intake of carbohydrates, not of protein, and is therefore not very effective for restoration of tissue mass. A recent clinical trial .found that dronabinol was also moderately effective in stimulating appetite in patients with severe anorexia nervosa, although the trial was only of four weeks duration so additional research is needed to speak to long-term efficacy.
(c) Pain relief
In Canada, Sativex® is approved for the relief of neuropathic pain (pain due to disease of the nervous system), of pain and spasticity (muscular stiffness) due to multiple sclerosis, and of severe pain due to advanced cancer. Sativex is undergoing clinical trials in the United States and is available on a limited basis by prescription in the United Kingdom and Spain. Numerous studies have confirmed the efficacy of smoked or vaporized cannabis or of oral cannabinoids in relieving neuropathic pain , in both short-term and longer-term trials . However, doses of oral dronabinol or smoked cannabis that were high enough to give a significant relief of pain also had significant psychoactive effects that some consider to be indicative of risk of addiction , and some clinicians regard the pain-relieving effect of cannabis as insufficient to outweigh its adverse effects .
(d) Anti-inflammatory actions
The endocannabinoids, as well as THC and other cannabinoids acting through CB1 receptors, and CBD acting through non-cannabinoid receptors, are all able to decrease the formation and release of chemical factors that give rise to inflammation . The endocannabinoid and the inflammatory systems co-exist in most tissues of the body, and the ability of CBD and some other cannabinoids to suppress inflammation reactions has been shown experimentally in such tissues as the endothelial lining of blood vessels .
(e) Uses in psychiatry
Post-traumatic stress disorder
The early use of cannabis for relief of anxiety, tension and sleeplessness is reflected in modern studies with cannabinoids. THC, CBD and THC–CBD combinations have been reported to improve sleep quality and duration as an additional benefit in patients being treated primarily for complaints such as pain, Parkinson’s disease, sleep apnoea, anxiety disorders and post-traumatic stress disorder (PTSD) .
Conclusions and Implications
Based on the available evidence, the approved therapeutic use of cannabis is mainly limited to the treatment of nausea, vomiting and certain types of pain, and the stimulation of appetite in AIDS patients. Further research is needed to determine its most appropriate use relative to that of other current treatments for nausea and pain. The possible benefits of combining cannabinoid therapy with other drugs might well lead to better methods of clinical use. Much of the more recent research has focused on a broad range of other proposed therapeutic uses for cannabinoids (e.g., multiple sclerosis, cancer, epilepsy, inflammatory conditions) and the results from this work are encouraging, but not yet well-enough supported by properly designed clinical trials to permit their recommendation for those clinical uses.