According to North American researchers, early research suggests that a popular non-psychoactive compound derived from marijuana may help prevent or treat COVID-19, and that this warrants further investigation in rigorous clinical trials.
Several recent laboratory studies on cannabidiol, or CBDThe results were promising, attracting media attention.
However, many other potential COVID treatments that have shown promise in test tubes, from hydroxychloroquine to various drugs used to treat cancer and other diseases, have ultimately failed to show benefits for COVID-19 patients when studied in clinical trials.
Marsha Rosner of the University of Chicago led a team that found that CBD appeared to help curb SARS-CoV-2 in infected cells in laboratory experiments. "Our results don't say it will work in patients. Our results argue for a clinical trial," she said.
Using small doses of highly purified CBD that approximate what patients receive in an oral drug already approved for severe epilepsy, for example, Rosner and colleagues found that CBD did not prevent the coronavirus from infecting cells in the test tubes.
Instead, it acted soon after the virus entered the cells, preventing it from replicating in part through effects on the inflammatory protein interferon. They found similar effects in infected mice, according to a report published in Science Advances.
"When they looked at a group of adults with severe epilepsy, the researchers found that those taking approved CBD had lower levels of COVID-19. But a retrospective look at a small number of patients does not provide conclusive information. Only extensive clinical trials can do that," said Rosner.
"I know my message is not something people want to hear," she said.
Small doses of tetrahydrocannabinol (THC) - the ingredient in marijuana that causes high cannabidiolic acid (CBDA), cannabidivarin (CBDV), cannabichromene (CBC) and cannabigerol (CBG) - did not prevent the virus from entering the cells or stop it from replicating, his team found.
"Not only did THC not work, but its combination with CBD prevented CBD from working," Rosner said.
NO COVID CARE AT THE CBD CLINIC
A separate team recently reported in the Journal of Natural Products that high doses of CBG and CBDA prevent the coronavirus from entering cells.
Richard van Breemen of Oregon State University told Reuters that the doses his team tested were not toxic to cells. "It is not yet clear that such high doses would be safe for humans," his team said.
"You want the lowest effective dose possible," Rosner said, because of the potential side effects when the drug is filtered through the liver.
The CBD her team tested was over 98 % pure, while the purity of commercial products is much lower. "People should not run out and get CBD from their favourite dispensary," she said.
CBD products have become widely available in many forms and have been promoted - often without evidence from clinical trials - as treatments for pain and other ailments.
Small trials of CBD in humans with COVID-19 are ongoing.
In a completed study, Brazilian researchers randomly assigned 105 patients with mild to moderate COVID-19 to receive CBD or placebo for 14 days with standard care. CBD had no apparent effect, according to an October report in Cannabis and Cannabinoid Research.
In another proof-of-concept study at the Sheba Medical Center in Israel, researchers randomly assign patients with mild COVID to receive CBD or a placebo.
A preliminary trial at Rabin Medical Center, also in Israel, aims to test the effect of CBD in critically ill patients. However, study leader Dr Moshe Yeshurun told Reuters that increasing the number of participants has been difficult because the current wave of Omicron-induced coronavirus "consists mainly of patients with mild to moderate disease".
Rosner's team is exploring the possibility of a clinical trial that would probably focus on asymptomatic or mild cases of COVID. Meanwhile, she fears that media reports exaggerating the potential of cannabinoids will lead people to self-medicate with CBD, and thus stop using masks and avoid vaccines.
They added: "We wish we could say specifically" that a certain dose of cannabinoids is useful, she said, but at this stage "antibodies induced by vaccines and antibody-based drugs are much more effective in blocking infection".
We remind our dear readers that CBD is not yet considered a medicineAs the benefits of CBD on the body are not yet proven, we invite you to contact your doctor to find out the best use of your CBD.