A drug made from chemicals found in marijuana has now entered human trials as a treatment for schizophrenia.
GW Pharmaceuticals announced on Monday that it has started Phase 2 clinical trials on a drug made from the marijuana compound cannabidiol (CBD).
The company, which holds the only license for growing cannabis in the UK, says the new drug features “purified CBD” as its active ingredient. Early findings show promise for improving symptoms of schizophrenia and suggest the drug can reduce the side effects of current antipsychotics when used together.
While marijuana is known to cause temporary psychosis-like effects, it is not CBD, but THC, that’s responsible. THC is the chemical in marijuana that causes the high. However, studies suggest CBD has an opposite effect.
“CBD is a constituent of traditional cannabis”“CBD is a constituent of traditional cannabis and tends to counteract the effects of THC,” explains Robin Murray, professor of psychiatric research at King’s College London. Some varieties of cannabis have higher CBD levels than others, he adds.
So far, a single trial has been conducted on CBD as an antipsychotic. The study, published in the journal Translational Psychiatry in 2012, compared CBD with the traditional antipsychotic amisulpride and found CBD was just as effective, but caused far less side effects.
Now the challenge for GW Pharmaceuticals is to prove its effectiveness in a larger group of patients.
The company says the Phase 2 trial will enroll 80 patients and will investigate the drug, temporarily known as GWP42003, as an add-on to currently prescribed antipsychotics. Results are expected by the second half of 2015.
GW Pharmaceuticals also makes a marijuana-derived pharmaceutical called Sativex, which is being trialed for cancer pain, and Epidiolex, which is being trialed for children with treatment-resistant epilepsy.
Sativex is already approved in 24 countries for treating spasticity symptoms in multiple sclerosis, and is distributed through agreements with a number of large pharmaceutical companies.
GW Pharmaceuticals is also developing new cannabis treatments for brain cancer, ulcerative colitis, Type 2 diabetes, and adult epilepsy.