Preclinical experiments in human cells and mice suggest that cannabidiol, a primary active compound in hemp and marijuana (Cannabis sativa), may prevent SARS-CoV-2 replication early in the course of infection, shortly after the virus has entered the cells.
This is one of the main conclusions of a study published in the journal “Science Advances”, led by researchers from the University of Chicago, in the United States, who nevertheless strongly reject the self-administration of this compound for Covid-19: it is needed more research and unanswered questions remain about the optimal dose, formulation, or mode of administration.
Furthermore, a correlative analysis of 1,212 patients who had a history of using cannabidiol (CBD) to treat seizures showed a substantially lower rate of SARS-CoV-2 infection, compared to matched control groups. This is currently the only FDA-approved use for CBD.
Not for self-consuming
Long Chi Nguyen and his team, who emphasize the importance of not self-consuming this substance, advocate conducting rigorous clinical trials that evaluate the potential of CBD as a therapeutic intervention for Covid-19, including its possible effects throughout the entire course of SARS-CoV-2 infection.
According to the scientists, the results provide “a strong justification for doing so,” says a summary of the article provided by the journal, such as cannabidiolic acid, cannabidivarin, cannabichromene and cannabigerol.
In addition, they also found that tetrahydrocannabinol (THC), the main psychoactive compound in C. sativa grown for use as marijuana, could strongly counteract the antiviral effects of CBD that they observed.
The authors state that this finding “essentially eliminates the feasibility of marijuana serving as an effective source of antiviral CBD.” The researchers treated human lung cancer cells expressing the ACE2 receptor—the key entry point for SARS-CoV-2—with CBD two hours before infection with the virus.After 48 hours, the team observed strong inhibition of viral replication, with no observable toxic effects.
The researchers repeated these experiments with two other human cell types and three variants of the virus (alpha, beta and gamma), all with comparable results.Noting that some previously investigated therapies for SARS-CoV-2 showed promise in cell experiments but did not work well in live animal tests, Nguyen and his team also tested their results in mice expressing the human ACE2 receptor.
They injected mice with CBD twice a day at two different doses for a week before SARS-CoV-2 infection and continued for four days after infection.At both the lowest and highest doses, CBD reduced viral load, and none of the mice lost weight or showed signs of clinical disease.
Preclinical efficacy
“These results establish the preclinical efficacy -tissues and animal models- of CBD as an antiviral drug for SARS-CoV-2 during the early stages of infection,” the authors of the work conclude.
