Researcher Gleice K. Silva-Cardoso, from the Graduate Program in Psychobiology at the FFCLRP (Faculty of Philosophy, Sciences and Letters of Ribeirão Preto) at USP, believes that CBD is a promising strategy in the treatment of chronic neuropathic pain, since that the cannabinoid system plays an essential role in the pain sensitivity circuit.
The endocannabinoid system (found in the brain and in several other places in the human and animal organism) was discovered in the late 1980s, and, since then, several national and international studies involving the therapeutic effects of CBD have gained strength.
An article by Gleice K. Silva-Cardoso was published in the journal Neuropharmacology. The results are from the pre-clinical phase (tests carried out on laboratory animals), but they showed the therapeutic potential of CBD in reducing the perception of allodynia (pain to light stimuli, such as a simple touch) and thermal hyperalgesia (pain caused by increased heat) in animals with neuropathic pain.
According to professor Christie Ramos Andrade Leite Panissi, from the Department of Psychology at FFCLRP and research advisor, in addition to the decrease in pain, the scientists observed "activation of regions of the central nervous system related to the modulation of emotional responses".
As for the emotional factor, Gleice says that chronic pain never comes alone and is often associated with some comorbidity, "mainly, anxiety and depression". Thus, she believes that the disorder should be dealt with in a multifactorial aspect and not just a physical one.
The researcher's assessments are also based on previous results from another study she carried out at the University of Maryland, in the United States, when she evaluated neuronal activities (communication between neurons and their receptors) in an area located in the brainstem: the parabrachial nucleus, involved in modulating chronic pain perception and which has also been tested for cannabinoid receptors.
Therapy for pain and emotional responses is composed of flavonoids, more than 200 terpenes and more than 100 phytocannabinoids, among which the best known are cannabidiol (CBD, which has no psychoactive effect) and tetrahydrocannabinol (THC, which has a psychoactive effect.
As one of the most studied, cannabidiol is able to activate cannabinoid receptors present in the body and which are part of the endocannabinoid system. These receptors can be activated by endocannabinoid substances (produced by the body) and by cannabis derivatives, such as CBD or another synthetic agent.
Professor Christie highlights that the search for therapeutic agents, "especially for cases of chronic pain resistant to traditional treatments", confirms the relevance of the study, not only for the discovery of new drugs, but to investigate "new uses of compounds already known and the possibilities of their joint action, minimizing possible undesirable side effects.
Gleice considers that her study findings may point to CBD as an adjunct in the treatment of chronic pain that can also reverse anxiety-like behaviours. If this component of Cannabis helps to modulate pain aversion, as noted, it does so by accessing "not only the mechanical relief part of the animal but also the question of this modulation of perception."
Despite celebrating the results, Professor Christie recalls that the study is still pre-clinical and that more research should be carried out on the use of cannabidiol and other cannabis derivatives "until they are indicated for clinical use in the treatment of chronic pain".
Treatments with cannabidiol Gleice reports that, currently, there are "a range of options for studies with the use of cannabidiol in various diseases", mainly focusing on its properties "in comorbidities and neuropsychiatric diseases". The substance has shown analgesic and immunosuppressive pharmacological benefits, with therapeutic action for anxiety, sleep and movement disorders, "which makes it a substance with great therapeutic potential", notes Christie. Products with CBD are already marketed in other countries and "indicated for the treatment of epilepsy, Parkinson's or Alzheimer's, as well as analgesics in terminal cancer patients", says the professor.
But, in Brazil, cannabidiol-based drugs that Anvisa authorizes "have as their main indication the treatment of muscle spasms related to multiple sclerosis", she says.