Common name: Cannabis
Other names: Weed, marijuana, hash, hemp
Latin name: Cannabis sativa
Affinities: Nervous system, immune system
Actions: Analgesic, anodyne, sedative, antispasmodic, hypnotic
Diseases: Multiple sclerosis(1), pain syndromes(1)
Parts used: Flower
Characteristics: Cannabis is a flowering plant native to central Asia and grows wild in open and disturbed habitats like hill-sides and riverbanks (Schultes et al., 1974). It is one of the most widely propagated and genetically variable plants due to extensive human use.
History: The first medicinal use of cannabis appears to have originated from the Himalayan regions of Asia (Kalant et al., 2001). From here it spread gradually into India, North Africa, and across the desert into sub-Saharan Africa. Cannabis was also included in traditional Indian medicine and its uses had similarities with those for which it is advocated in our modern society. These include sedative, anticonvulsant, and anxiolytic actions which made it useful for alcohol and opiate withdrawal, appetite stimulation, analgesia, and relief of diarrhoea. Its first medicinal use in Europe was in England because Professor O’ Shaughnessy, who was living in Calcutta, observed the use of cannabis in traditional Indian medicine. He sent samples back to a firm in London for analysis and clinical trials, cannabis extracts were adopted into the British Pharmacopoeia and later the American Pharmacopeia, and were widely used as a sedative, hypnotic, and anticonvulsant in the later 19th century and early 20th centuries. By 1932, cannabis had been dropped from the British Pharmacopoeia coinciding with the arrival of synthetic drugs and extraction of pure opiates, and its medicinal use declined.
Science: Cannabis contains over 60 aromatic hydrocarbon compounds that are characteristic of the herb, known as cannabinoids (Wade et al., 2004). The principle neuroactive compound of cannabis is 9-tetrahydrocannabinol (THC), but other derivatives have synergistic and therapeutic activity. Of these, the most promising is cannabidiol (CBD) and it is nonpyschoactive and legal. CBD may be legally extracted from hemp. CBD has been found to have anti-inflammatory activity (Costa et al., 2004; Malfait et al., 2000) and results from in vivo models suggest it may be an effective treatment for arthritis. Cannabinoids have been found to kill tumour cells (Carracedo et al., 2006) and a THC compound was found to reduce oxidative stress (Raman et al., 2004). Studies in humans are often using a patented and standardised extract of both THC and CBD called Sativex. There is strong evidence Sativex is effective in reducing some of the symptoms of multiple sclerosis (Wade et al., 2004). There is also good evidence that it is effective in reducing different types of chronic pain, including cancer (Johnson et al., 2010) and neuropathic pains (Nurmikko et al., 2007).
Safety: There are justified concerns that cannabis use may increase the likelihood of certain individuals developing psychosis and schizophrenia (Andréasson et al., 1987). It is associated with lethargy and causes insomnia after long term use and discontinuation. Avoid use when pregnant or breast feeding.
In contrast, the cannabis extract, cannabidiol, is medicinally effective and thought to be safer. It is not psychoactive. Still, avoid during pregnancy and breast feeding as a precaution.
Dosage: For cannabidiol follow the directions on packaging.
Research on models
Anti-inflammatory activity: Researchers have found that CBD reduces inflammation in an in vivo model (Costa et al., 2004). Another study similarly found CBD to reduce inflammation in an in vivo model of arthritis (Malfait et al., 2000).
Anti-tumour activity: One study found that cannabinoids increased apoptosis (cell death) of pancreatic tumour cells (Carracedo et al., 2006).
Anti-oxidant activity: A study found that a THC compound was effective in reducing oxidative stress in the spinal cord of an in vivo model of Amyotrophic lateral sclerosis (Raman et al., 2004).
Research on humans
Multiple sclerosis: A study (n = 160, randomised, double blind placebo controlled) found applying up to 120 mg THC and 120 mg CBD per day (Sativex) for 6 weeks for treatment significantly alleviated spasticity and may reduce bladder symptoms also, but this was not quite significant (Wade et al., 2004).
Cancer pain: One study (n = 177, randomised, double blind placebo controlled) examined whether Sativex reduced pain in patients with intractable cancer related chronic pain who were not adequately responding to opioids (Johnson et al., 2010). Dose varied and was applied as needed. Over two weeks a significant reduction in pain was observed.
Neuropathic pain: A study (n = 125, randomised, double blind placebo controlled) investigated whether Sativex reduced neuropathic pain characterised by allodynia (Nurmikko et al., 2007). Over 5 weeks, substantial reductions in pain metrics were observed that were strongly significant.
Carracedo, Arkaitz, et al. “Cannabinoids induce apoptosis of pancreatic tumor cells via endoplasmic reticulum stress–related genes.” Cancer research 66.13 (2006): 6748-6755.
Costa, Barbara, et al. “Oral anti-inflammatory activity of cannabidiol, a non-psychoactive constituent of cannabis, in acute carrageenan-induced inflammation in the rat paw.” Naunyn-Schmiedeberg’s archives of pharmacology 369.3 (2004): 294-299.
Johnson, Jeremy R., et al. “Multicenter, double-blind, randomized, placebo-controlled, parallel-group study of the efficacy, safety, and tolerability of THC: CBD extract and THC extract in patients with intractable cancer-related pain.” Journal of pain and symptom management 39.2 (2010): 167-179.
Malfait, A. M., et al. “The nonpsychoactive cannabis constituent cannabidiol is an oral anti-arthritic therapeutic in murine collagen-induced arthritis.” Proceedings of the National Academy of Sciences 97.17 (2000): 9561-9566.
Nurmikko, Turo J., et al. “Sativex successfully treats neuropathic pain characterised by allodynia: a randomised, double-blind, placebo-controlled clinical trial.” Pain 133.1 (2007): 210-220.
Wade, Derick T., et al. “Do cannabis-based medicinal extracts have general or specific effects on symptoms in multiple sclerosis? A double-blind, randomized, placebo-controlled study on 160 patients.” Multiple Sclerosis Journal 10.4 (2004): 434-441.