Every day there is more research in which it is shown that cannabis can be both an adjunct to existing conventional drugs to treat pain, as an alternative, natural, organic or ecological, effective and cheaper medicine for these drugs.
Pain is a universal disorder that is one of the biggest challenges for public health, both in clinical and economic terms and that not only affects the person who suffers it, but has an immense impact on their environment. There is nothing more desperate for a patient and his relatives than the first’s suffering of chronic pain, which when not treated properly can affect the dignity of the person. Numerous medical pathologies present with pain: arthritis, migraines, neuronal lesions, cancer and much more. Numerous drugs for the treatment of pain are currently available with a varying degree of efficacy, according to each patient and each pathology. Every day there is more research in which it is shown that cannabis can be both an adjunct to existing conventional drugs to treat pain, as a substitute medicine for these drugs. In fact, among all patients who use medicinal cannabis, one of the main pathologies for which they use it is to treat chronic pain.
Patients registered in the medical cannabis programs of the United States, 92.2% of patients use it for the treatment of severe and chronic pain (173). A sample of 628 medical cannabis users in Canada, pain was among the three main symptoms. 72% of the patients reported that cannabis was always useful and 24% that it was frequently. Although slightly more than half of the total sample said to use other medications; Of these, almost 80% said that cannabis had fewer side effects than other drugs (174). Having this reference, it can be understood that even in this sense the acceptance of medical cannabis can be favorable for the scientific world, providing important value to patients and their obstacles to good health.
Clinical trials in chronic pain relief
In relation to an international sample that included patients from different European and North American countries, the main medical condition for which patients used medical marijuana was also chronic pain (29.2%) (175). In a survey conducted in the United Kingdom among patients who self-medicated with cannabis, 40% reported doing so for the treatment of pain and, in Spain, a survey conducted on 2250 patients on the use of medical cannabis to treat their medical conditions, Of which 5.8% responded, 44.6% said they used it to treat pain symptoms (176). Regarding the relief of symptoms, in a North American survey composed of 97% of patients with chronic pain, the degree of relief they experienced when using cannabis was asked: on a scale of 0 to 10 pain intensity, the decrease The average was 5 points (7.8 to 2.8) between before and after using cannabis, which implies an average relative decrease of 64%. Half of the respondents also reported experiencing relief from stress and anxiety secondary to the disease and almost half (45%) reported relief from insomnia. The majority of patients (71%) did not report experiencing adverse effects (177). These analyzes and also in other statistics we see the increase in use and positive applications, it is a fact that in many countries the legalization for its medical use is already being implemented and it will grow in high demand.
Receptors, endogenous cannabinoid system and effects
The endocannabinoid system works retrograde, that is, inhibiting the activation of signals in response to excessive neuronal activity. This inhibition of neuronal firing manifests itself in the pain pathways in the form of analgesia and reduced pain sensitivity. There is a great abundance of CB1 receptors both in the brain areas responsible for processing pain, and in the peripheral nerves that transmit painful sensations to the brain, as well as in the brain areas related to the effective assessment of pain (fronto-limbic areas). On the other hand, CB2 receptors play an important role in reducing inflammatory processes and, above all, in signaling pain and can be of particular relevance in chronic pain states. In addition, both anandamide and 2-AG have been shown to have analgesic properties in numerous animal model studies (178). The knowledge of the involvement of the endogenous cannabinoid system, together with the accumulation of evidence from animal research, indicates that pharmacological modulation by means of cannabinoids is an extremely interesting strategy for the treatment of refractory and chronic pain states.
So far, clinical trials have been carried out both with marijuana and with different natural and synthetic cannabinoids in which more than 1000 patients have participated, showing efficacy in different types of chronic pain, the majority of studies with patients with neuropathic pain ( 179) (a type of pain resulting from a lesion in the central and / or peripheral nervous system) that occurs in diseases of the nervous system such as multiple sclerosis, but also in other types of diseases such as diabetes. Both THC and its synthetic analogs (nabilone and dronabinol) and Sativex have been found useful in clinical trials conducted so far. For its part, the CBD, in addition to also possessing analgesic properties (180), its ability to reduce the adverse psychological effects of THC, as well as its potential as an anxiolytic, makes its combination with THC, or its presence in herbal cannabis, help with THC to facilitate its analgesic property.
Not only THC and CBD, the main phytocannabinoids of the cannabis plant, have analgesic properties. Other non-psychoactive phytocannabinoids such as tetrahydrocannabivarin (THCV), cannabigerol (CBG) and cannabichrome (CBG) are also throwing evidence. And what is more interesting: it seems that the terpenes present in the cannabis plant also interact with the phytocannabinoids to synergistically enhance the analgesic effect with them (181). Terpenes are molecules that provide smell and aroma to many food products and are designated by different regulatory agencies, including the FDA (Food and Drug Administration), as “generally recognized as safe.” This phenomenon makes the use of the cannabis plant, with its rich composition in different cannabinoids and terpenes, considered a more interesting strategy than the administration of isolated compounds (182), and that there is even evidence of studies in animal models that They point in that direction (183).
Finally, there are more and more clinical studies (184), research based on surveys (185) and anecdotal cases (186), which show how in patients with chronic pain in treatment with opiates, the use of marijuana allows them to reduce the amounts of opioids they drink. Something, on the other hand, that is in line with animal and pharmacological research, in which there are abundant studies in which it has been found that the combination of cannabinoids with opiates acts synergistically (187) so that lower doses are needed of opiates to achieve the analgesic effect, which considerably reduces the risk of overdose, which, unlike cannabis, in the case of opiates can be fatal. In fact, a recently published study has found that in the US states where the use of medical marijuana is legalized, the number of overdose deaths caused by analgesic drugs, mainly opiates, is 24.8% lower than in the other states (188).
Reference and support
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