Cannabis was in the news again recently with reports that prolonged and frequent use of a form of cannabis called skunk leads to a 5-fold increased risk of psychosis. Like no other illicit narcotic, cannabis has evoked more debate about its use with some proclaiming its dangers and others lamenting its therapeutic powers. The pharmacology of cannabis has become entangled in its politics which has unfortunately tarnished all sides of the argument.
Cannabis could be classified as a herb with particularly potent pharmacologic effects. Like all herbs (and herbal medicines) the product is a heterogeneous mix of chemicals that alters depending upon the plant variety and growing conditions. Skunk is at one end of the spectrum containing high quantities of tetrahydrocannabinol (THC) the main psychoactive component as well as a range of chemicals called terpenoids, that give cannabis its pungent aroma. At the other end of the (illegal cannabis) scale is hash, which contains lower amounts of THC but higher levels of another component called cannabidiol (CBD) which does not appear to be psychoactive and may act as an inhibitor of THC. This is not to say that hash is a safe drug, as CBD still has complex and only partly understood pharmacological effects. In fact this month the University Hospital Düsseldorf in Germany identified a number of deaths that were likely to be cannabis related (although others disagree - the arguments continue).
It may be surprising to some but there is yet another variety of cannabis that is low in THC and high in CBD that is sold legally - in some states in the USA anyway. The variety is called Charlotte’s Web, named after a 6-year old girl called Charlotte Figi who suffers from Dravet syndrome (a form of severe epilepsy). Her seizures have been controlled by the use of this particular variety of cannabis and CBD has now been developed into a pharmaceutical drug by GW Pharmaceuticals. The same company is developing cannabis-related drugs for multiple sclerosis and there is evidence to suggest CBD may have utility in cancer therapy.
Of course, the development of successful drugs from plants is nothing new; digoxin for the treatment of angina is probably the most commonly quoted. Development of legitimate pharmaceuticals from cannabis is marred on both sides however, as research is limited by inhibitory legalities on the one hand and on the other, there are those that will just believe in its magical properties irrespective of the evidence. Good scientific enquiry into cannabis related pharmaceuticals is clearly warranted and then let the science decide which side is right.