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Caroline Johnson: Review of medical cannabis is worth exploring

The case of Billy Caldwell has shone a light on the use of medicinal cannabis in this country and highlighted the need for the government to explore this issue further. I am glad that the Home Office has acted swiftly in granting an emergency licence to allow the return of his cannabis based medicine, and that Billy himself is much better.

Following the government’s announcement of a review of medicinal cannabis, it is worth exploring the differences between this and recreational cannabis.

This boils down to the respective concentrations of two main active ingredients, THC and cannabidiol, present in cannabis. THC makes you feel ‘high’, is illegal above a certain concentration and may cause psychological problems or psychosis, especially if used over a prolonged period of time.

THC concentrations in recreational cannabis vary but are especially high in ‘skunk’ varieties. It has anticonvulsant effects, but may cause seizures in some people too. Cannabidiol, on the other hand, reduces fits, doesn’t make you feel ‘high’ and probably doesn’t lead to psychosis or psychological problems.

It is this component that perhaps offers the most promise. For example, Epidiolex is a quality assured, cannabidiol-based drug, containing less than 0.1% THC (and is therefore legal); it has been used in clinical trials in this country, including in children with epilepsy. Sativex is another cannabis-based drug prescribed in the UK. It contains cannabidiol and THC in roughly equal but low (and therefore in the case of THC, legal) amounts.

All UK medicines undergo rigorous pharmaceutical testing to ensure their quality, safety and efficacy before being prescribed to patients. The same cannot be said of non-medical grade cannabis oils. ‘Cannabis oil’ is a loose term that includes a variety of products containing varying concentrations of key ingredients. They may have a high concentration of THC – a compound believed to precipitate psychotic disorders in some people – or a negligible amount. Without going through the stringent licensing process, patients and doctors cannot be assured of the quality and safety of these products.

As a Consultant Paediatrician, I would not feel comfortable prescribing a drug to children in my care that had not been produced to high standards. Indeed, to write a prescription for a new drug one would need to know how much to prescribe, in what form, in what frequency it should be taken, how it may interact with the patient’s other medications and what the side effects are. Without this information patients may be at risk. The past is littered with examples of unexpected, adverse consequences of medications.

The question is: do we test these products properly so we know what blend of cannabis compounds are safe and ensure they’re properly produced to pharmaceutical standards? Or do we just allow patients to take non-pharmaceutically produced products and see what the outcome is? I believe the answer is clear: we should continue an evidence-based, clinically-led approach to licensing new drugs to ensure that patients are protected. We need to do this without delay so patients can benefit as soon as possible.