The two most studied compounds in cannabis may not balance each other out like it's commonly claimed.
THC (delta-9-tetrahydrocannabinol) is the main intoxicating part of the cannabis plant, and CBD (cannabidiol) is the main non-intoxicating part.
The two are often pitted against each other, but their effects on the human body may not be in a tug-of-war after all.
A new double-blinded clinical trial has poked a hole in the hypothesis that CBD can take the edge off THC, reducing negative side effects like intoxication, cognitive impairment, or anxiety.
Instead, at high enough doses, CBD seems to actually enhance the intoxicating effects of THC.
In experiments, when participants swallowed 9 milligrams of THC and 450 milligrams of CBD, they reported feeling 'high' in body and mind significantly more than when taking THC on its own.
Analyzing their blood, researchers noticed elevated concentrations of THC and its psychoactive metabolites. They suspect that the high dose of CBD is inhibiting the metabolism of THC in the body, thereby exacerbating its psychoactive effects.
While such interactions were also apparent at a lower CBD dose of 30 milligrams, these smaller amounts did not have a significant impact on subjective feelings of intoxication.
"Regardless of the administration route, the hypothesis that CBD attenuates THC effects remains contentious, and our results add to a growing body of evidence against it," explain the authors of the clinical trial, led by Andriy Gorbenko from the Center for Human Drug Research in the Netherlands.
The current trial was conducted among healthy male and female volunteers between the ages of 18 and 45. Each participant had past experience with cannabis but had not used the drug for at least three weeks before the experiment.
On five separate occasions, participants arrived at the clinic to take an oral drug, which either contained a placebo, pure THC, or a mix of THC and CBD. Neither participants nor researchers knew who was taking what.
In the hours after ingestion, participants had their subjective feelings of pain and intoxication measured using two validated tests. Blood samples were taken before the dose, and then again at multiple intervals up to 8 hours after.
The lower doses of oral CBD did not influence the intoxicating effects of THC, but the highest dose of CBD had a significant impact on most of the psychoactive measures examined.
The team explains that a "drug-drug interaction with CBD as the perpetrator drug and THC as the victim drug appears the most likely explanation for the pharmacokinetic findings of this study."
What's more, the level of CBD did not have any impact on participants' subjective ratings of pain, which supports previous clinical trials that found CBD products don't relieve chronic pain on their own.
The trial is only small, and it only considers oral ingestion of CBD and THC. At this point, however, inhalation studies have yet to produce convincing evidence that CBD mitigates the effects of THC, either.
Neuropharmacologist Geert Groeneveld told Psypost that their team at the Center for Human Drug Research has continued to run trials using very high doses of pure CBD.
"We haven't published this yet," Groeneveld told reporter Eric Dolan, "but we can tell you that there is no evidence whatsoever that CBD is active on the central nervous system. It does not cause sedation or lead to subjective drug effects that can be picked up by our very sensitive test battery… "
Cannabis is now the most regularly used recreational drug in the United States, surpassing even alcohol. It's about time we knew what effect its two main compounds are having on the human body.
