The Cannabis plant is a natural product from which more than 100 apparently unique metabolites (cannabinoids) have been identified. Many of these have been found in human plasma following consumption of Cannabis preparations. The most well-recognised is tetrahydrocannabinol, THC, because of its well-documented psychotropic effects mediated through activating CB1 cannabinoid receptors. It has been used clinically as an anti-emetic and for treating glaucoma.
Cannabidiol, CBD, is also a prominent metabolite from the plant, which lacks the psychotropic effects of THC, since it is not an agonist at CB1 cannabinoid receptors. It is in advanced trials for treating childhood epilepsy, but may also have benefit in schizophrenia or post-traumatic stress disorder. The molecular mechanisms of action of CBD are not precisely defined, but may involve multiple targets.
A standardised combination of THC and CBD is available in many countries, including the UK as a licensed medicine for treating the symptoms of multiple sclerosis.
There is a lack of clear understanding of the biological effects of the majority of the other cannabinoid metabolites from the plant, which may have applications in inflammatory disorders, nausea and metabolic disorders, such as type II diabetes.
In many countries, Cannabis itself is licensed as a medicine for indications such as pain relief or the weight loss associated with terminal cancer or AIDS. However, preparations from Cannabis are highly variable in terms of the spectrum and concentrations of cannabinoid content, as well as other compounds present in the plant, such as the terpenoids, which have also been proposed to have independent bioactivity.
Commentary by Steve Alexander (@mqzspa) & Anthony Davenport