CBD is a major phytocannabinoid and can account for up to 80% of the plant's extract. Generally speaking it is a non psychoactive component, but it is nonetheless physiologically active, and contributes greatly to the medicinal effect of the plant. So it can be considered a non-euphorant, but in low doses can act as a stimulant, but with higher doses is actually a sedative. CBD has been proven to be a protector of neurons, a neuroprotectant, particularly in the brain, as well as peripheral tissues and nerves. For this reason, CBD may be effective in brain injury, concusiion, and concussive traumatic encephalopathy (CTE) as for example in football players.
As an immunomodulatory agent, it can have a consequence on your immune system, and be a benefit in some diseases. Like THC it is also anti-inflammatory, and an analgesic agent for specific types of chronic pain and nueropathic diseases. It is a strong anti-convulsant and proven to be very useful in prevention and reduction in epileptic seizures, in both adults and children. For this purpose high doses are given, and also strains high in CBD are being advanced and developed. A drug epidolex, by GW Pharmaceuticals in the UK, has been used succesfully in epilepsy and soon coming to the US.
CBD has an interesting and somewhat complex interaction with THC. On one hand, CBD acts as an indirect antagonist of the CB1 and CB2 receptors, thus limiting THC's effect by occupying receptor space that becomes unavailable for THC binding. On the other hand, it may increse THC activity by increasing the receptor density for THC. In this fashion it may potentiate THC's effects. Also, CBD may exert a pharmacological action thru it's inhibition of FAAH (fatty acid amide hydrolase) which breaks down THC. By inhibiting the breakdown of the enzyme to degrade THC it raises the levels in the body, as well as those of other endocannabinoids (anadamide) so it can enhance their effects. It prolongs the effect of THC by this same mechanism.
Cannabidiol may also prolong the effects of THC via inhibition of cytochrome P450, another enzyme that breaks down THC. CBD has also been found to be an antagonist of GPR55, a receptor found in the brain, so it also effects neural transmission thru this effect. It has been shown to delay the re-uptake of endogenous neurotransmitters adenosine and anadamide. It has been shown to activate the 5HT receptor and increase serotonin levels by preventing the reuptake of serotonin from the pre synaptic neuron. This increase in serotonin may be involved in the antidepressant, anxiolytic, and neuroprotective effect.
Hemp products and hemp plants, from the species cannabis ruderalis, is often high in CBD and an excellent source. CBD is also found in tinctures for subligual use, pills, capsules, lotions, and in cannabis with a high CBD:THC ratio. CBD purchased thru non reputable sources, and usually the internet, may not be effective due to low potency or inexact concentrations. It is notable as well that CBD is potentiated by THC to some extent and more therapeutic in combination, ie. THC and CBD together.
CBD research is ongoing, and techniques of extraction and methods of use are still evolving. Basically for medical cannabis to be truly therapeutic, both THC and CBD are necessary. For this reason, please insure that the strains being used have each of these ingredients, especially when used medicinally.