There is an interesting article about transdermal cannabidiol (CBD) being useful for moderating the brain damage caused by binge drinking – here is the enthusiastic High Times review. As positive as I am about CBD, I think a few caveats are in order. First and most obviously this is a rat study and is far from proving anything in humans.
The original article is set to come out in Pharmacology Biochemistry and Behavior and is an interesting read. In their introduction of what is known, they point out that previous studies have shown positive effects of antioxidants, including CBD, on the neurodegenerative effects of alcohol. They also note that CBD is poorly absorbed by the oral route, with a bioavailability of only 6%.
The initial part of the experiment looked at different strengths of CBD gel. The blood levels of CBD for different formulations was measured, as well as what the differences were in neurodegeneration after alcohol binging. There was a decrease noted, though it was only with the highest strength of the gel and there wasn’t a dose dependent effect noted (generally, effect should increase with increasing drug strength – this increases the confidence that the result is due to the drug, rather than statistical error/randomness).
The second part of the study used a different formulation altogether of gel vehicle, though one designed to deliver a similar plasma level to the gel strength that was effective in part one of the experiment. The authors report that the transdermal formulation and the intraperitoneal injection produced a similar reduction in neurodegeneration from alcohol toxicity. Once again I have issues with the dose response relationship as they also seem to demonstrate that the intraperitoneal injection produces blood levels of CBD that are an order of magnitude greater than those achieved with the patch and yet the neuroprotective effect is not significantly different between the two.
In the conflict of interest section it is also noted that two of the four authors have significant shareholdings in Alltranz, a company which has recently been issued a patent for the transdermal administration of cannabidiol Transdermal patches are an excellent way to deliver medications and have shown particular success with fentanyl and nicotine. Transdermal cannabinoids would be a welcome addition to clinical practice and I wish Alltranz well with their further developments. However, I don’t believe that you can draw any conclusions from this study about whether transdermal cannabidiol is useful in humans for warding off neurological injury from alcohol excess. It wouldn’t be wrong to take a CBD capsule after a night of heavy drinking; in that there may be benefit and there is unlikely to be any harm.