Cannabinoids are a group of chemical substances which affect their specific receptors in the body, CB1 and CB2. They are naturally produced in the body (endocannabinoids), extracted from the cannabis plant (phytocannabinoids), or synthesized by human to exert a similar action (synthetic cannabinoids). Although these compounds were formerly known since long period of time, the discovery of the endocannabinoid system, including the specific receptors, grasped the attention of scientists to the possible medicinal applications of cannabinoids.
As such, the mechanisms of action of different compounds were extensively investigated. The major plant-derived cannabinoids are tetrahydrocannabinol (THC) and cannabidiol (CBD). The former is considered the main psychoactive component, which means that it causes remarkable changes in brain function, perception, and mood. On the other hand, CBD mimics the physiological action of THC but without exerting a psychoactive action. This study reviewed the different effects of THC and CBD therapy on the body.
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Some experimental studies on rats revealed that CBD might augment the depressant action of THC, while reducing its excitatory and emotional side effects. However, other reports showed that there is no effect of adding CBD to THC preparations. In human, evidence demonstrated that CBD infused to patients receiving THC resulted in reduction of anxiety and panic but with more pleasurable symptoms. In contrast, the “high” sensation was reduced in some patients who smoked cannabis with THC along with CBD therapy. Given that the effects of THC on convulsions were promising, it is plausible that adding CBD would be effective with minimal side effects.
The use of oral cannabis extracts has been studied in multiple diseases. For example, Cannador extract (containing variable proportions of THC and CBD) was effective only at high doses for the treatment of spasms (involuntary muscle contraction). Furthermore, a combination of THC and CBD led to improvement of spasticity in patients with multiple sclerosis involuntary movements that can be seen in the Parkinsonian patients over long periods of oral treatment.
When it was given via the oromucosal route, THC and CBD therapy was highly efficacious for controlling neuropathic pain, spasm, and spasticity with few side effects and/or withdrawal symptoms.
Recent studies showed that CBD may be beneficial to ameliorate the symptoms of Alzheimer’s disease and reduce the behavioral and psychotic adverse effects of THC. Additionally, such combination would improve the motor and nervous disturbances in amyotrophic lateral sclerosis. In addition to this neuroprotective effect, the combined therapies of CBD and THC can selectively kill cancer cells despite the scarcity of relevant clinical trials.
A combination of THC and CBD therapy would potentially augment the action of THC with minimization of its side effects. More cannabinoid compounds may be added to this combination to potentiate its actions and this should be considered in future clinical trials.