Vaping Pot More Powerful Than Smoking It

F. Perry Wilson, MD, MSCE


December 04, 2018

Welcome to Impact Factor, your weekly dose of commentary on a breaking medical study. This week, we're going green with a look at a study appearing in JAMA Network Open[1] that takes the lead for my favorite sentence ever to appear in a medical journal:

Source: Spindle TR, et al.[1]

"Historically, cannabis has predominantly been smoked using various implements such as joints, pipes, bongs, and blunts."[1] I think the fact that this carries a footnote is the best part.

In any case, recreational marijuana has been legalized in nine states, and it seems likely that more are on the way. (I'm looking at you, Connecticut Governor-elect Ned Lamont.)

Source: AP/Shutterstock

People who haven't ever smoked pot—or maybe haven't since that one time they tried in college and spent 2 hours trying to define what a "corner" really is—may be trying it again. And when they try, they may use the new hotness of vaping to deliver THC into their bloodstream.

Source: Alamy

Now, thanks to researchers at Johns Hopkins, we have high-quality pharmacokinetic and pharmacodynamic data to suggest just what the reefer will do in that situation.

OK, this is a small study. They took 17 healthy adults who were not frequent users of marijuana—most of them hadn't smoked in at least a year. Each of those 17 individuals came in once a week for 12 weeks.


During their visit they either smoked or vaped pot (at 10 or 25 mg of THC) or placebo pot. These visits were randomized, allowing each participant to serve as her or his own control, allowing for pretty robust conclusions despite the small sample size.

After they inhaled—and by the way, they were forced to smoke all of what they were given—they underwent a battery of cognitive tests and had periodic blood samples [taken] for THC content.

All of the tests told the same story: Vaping delivered substantially more THC to the bloodstream and had substantially greater cognitive effects compared with smoking.

Take a look at the peak THC levels under the different conditions: Vaping 10 mg of THC led to nearly as high THC levels as smoking 25 mg of THC.


And the subjective effects were right in line, too. Vaping led to higher scores for "pleasant" feelings, but also more paranoia and dry mouth.


Cognitive ability suffered more in the vaping group as well, particularly in the "divided attention" task. So, yeah—don't, you know, dooby and drive.


Twenty-five milligrams of THC was enough to make two participants vomit, but those doses actually pale in comparison with what is available at recreational marijuana shops. At a Massachusetts dispensary, for example, a 1-g joint called "Facewreck," containing 22% THC, runs you 15 bucks.[2]


That's roughly 10-fold higher amounts of THC than what was used in the high-dose group in this study.

So, what's the take-home? People who haven't smoked pot in a long time—be careful. The effects are real. If you're going to do it, realize that vaping will deliver more drug, don't operate machinery under any circumstances, and remember that just because a study is small, it doesn't mean that it should totally harsh your mellow.


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