Vapourised pot means a higher high

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A smokeless method of vapourising and then inhaling pot packs a much more powerful punch than simply smoking weed, according to research published in JAMA Network Open, reports Dennis Thompson for HealthDay. That could raise safety concerns for users – around driving, for example.

Marijuana vaporizers heat pot to a temperature just below combustion, allowing people to inhale the intoxicating chemical THC from the plant material without breathing in any smoke.

This method produced much more intoxication in a small group of test participants than smoking the same amount of marijuana through a typical pot pipe, according to the report published online on 30 November in JAMA Network Open.

The study participants also had more adverse effects associated with their pot use when they used vaporizers, and had more pronounced impairment of their ability to think and control their movements, the researchers said.

“It’s often a fine line between someone getting the drug effect they desire and having a drug effect that’s too strong, and maybe produces paranoia and adverse effects that are uncomfortable for the person,” said lead researcher Tory Spindle.

“That sort of thing might be more likely with vaporizers,” he added. Spindle is a postdoctoral research fellow at Johns Hopkins University School of Medicine, in Baltimore.

These vaporizers aren’t to be confused with “vaping” – a term used to describe electronic cigarettes.

Survey data has shown that vaporizing is becoming a more popular method of using pot, particularly in states that have legalized recreational use of the drug, Spindle said.

“It heats it to a temperature that doesn’t reach combustion,” Spindle said of the vaporizing devices. “If you look at the cannabis after it’s done vaporizing, it doesn’t turn into the black ash material it would when you smoke it. It looks exactly like it did when you put it in.”

To see if vaporizers deliver a different high than smoking pot, Spindle and his colleagues recruited 17 healthy adults who were not frequent marijuana users and asked them to both smoke pot from a pipe and inhale the fumes produced by a vaporizer.

The same 25-milligram dose of pot produced a significantly stronger high when vaporized than when smoked, the findings showed. Pre-rolled joints sold at dispensaries typically contain 1 gram of pot.

People on vaporized pot also showed greater impairment than when they smoked the drug, based on testing that gauges the ability to think, reason and perform fine motor skills.

Vaporized pot came with more side effects as well, including heart racing (24 percent versus 18 percent for smoked), paranoia (17 percent versus 10 percent), hunger (38 percent versus 33 percent), dry mouth (67 percent versus 43 percent), and red eyes (25 percent versus 16 percent).

Blood tests revealed that people had much higher levels of THC in their circulation after using a vaporizer, about 14.4 nanograms per milliliter (ng/mL) of blood compared with 10.2 ng/mL when they smoked pot.

The effects typically wore off between six to eight hours for both vaporized and smoked pot, the researchers said.

Heating but not burning pot appears to ensure that more of the weed’s high-producing chemicals are imbibed by the user, Spindle said.

“Our theory is that when you combust cannabis, more of the THC is lost due to the combustion process,” Spindle said. “The vaporizer is a more efficient delivery method than the smoked cannabis.”

People who don’t use marijuana regularly should approach vaporizers with caution, said Nadia Solowij, a professor at the University of Wollongong in Australia.

“There is a perception that it is a safer route given that it avoids burning the plant matter, thus reducing toxins formed by that process,” said Solowij, who wrote an editorial accompanying the new study.

“These findings raise concerns for inexperienced users, which include those using [pot] both recreationally but also trying cannabis for medical reasons,” she added.

“It may be wise to use a smaller amount of cannabis in a vaporizer to achieve the desired effect,” Solowij concluded.


Acute effects of smoked and vaporized cannabis in healthy adults who infrequently wse cannabis–A crossover trial

Key points

How does smoked and vaporized cannabis acutely influence subjective drug effects, cognitive and psychomotor performance, and cardiovascular measures in healthy adults who infrequently use cannabis (>30 days since last use)?


In a crossover trial of 17 healthy adults, inhalation of smoked and vaporized cannabis containing 10 mg of Δ9-tetrahydrocannabinol (THC) produced discriminative drug effects and modest impairment of cognitive functioning, while inhalation of a 25-mg dose of THC was associated with pronounced drug effects, increased incidence of adverse effects, and significant impairment of cognitive and psychomotor ability. Vaporized cannabis produced greater pharmacodynamic effects and higher concentrations of THC in blood compared with equal doses of smoked cannabis.


Significant, sometimes adverse, drug effects can occur at relatively low THC doses in infrequent cannabis users, and accordingly these data should be considered with regard to regulation of retail cannabis products and education for individuals initiating cannabis use.


Vaporization is an increasingly popular method for cannabis administration, and policy changes have increased adult access to cannabis drastically. Controlled examinations of cannabis vaporization among adults with infrequent current cannabis use patterns (>30 days since last use) are needed.


To evaluate the acute dose effects of smoked and vaporized cannabis using controlled administration methods.

Design, setting and participants

This within-participant, double-blind, crossover study was conducted from June 2016 to January 2017 at the Behavioral Pharmacology Research Unit, Johns Hopkins University School of Medicine, and included 17 healthy adults. Six smoked and vaporized outpatient experimental sessions (1-week washout between sessions) were completed in clusters (order counterbalanced across participants); dose order was randomized within each cluster.

Interventions. Cannabis containing Δ9-tetrahydrocannabinol (THC) doses of 0 mg, 10 mg, and 25 mg was vaporized and smoked by each participant.

Main outcomes and measures

Change from baseline scores for subjective drug effects, cognitive and psychomotor performance, vital signs, and blood THC concentration.


The sample included 17 healthy adults (mean [SD] age, 27.3 [5.7] years; 9 men and 8 women) with no cannabis use in the prior month (mean [SD] days since last cannabis use, 398 [437] days).

Inhalation of cannabis containing 10 mg of THC produced discriminative drug effects (mean [SD] ratings on a 100-point visual analog scale, smoked: 46 [26]; vaporized: 69 [26]) and modest impairment of cognitive functioning. The 25-mg dose produced significant drug effects (mean [SD] ratings, smoked: 66 [29]; vaporized: 78 [24]), increased incidence of adverse effects, and pronounced impairment of cognitive and psychomotor ability (eg, significant decreased task performance compared with placebo in vaporized conditions).

Vaporized cannabis resulted in qualitatively stronger drug effects for most pharmacodynamic outcomes and higher peak concentrations of THC in blood, compared with equal doses of smoked cannabis (25-mg dose: smoked, 10.2 ng/mL; vaporized, 14.4 ng/mL).

Blood THC concentrations and heart rate peaked within 30 minutes after cannabis administration and returned to baseline within 3 to 4 hours. Several subjective drug effects and observed cognitive and psychomotor impairments persisted for up to 6 hours on average.

Conclusions and relevance

Vaporized and smoked cannabis produced dose-orderly drug effects, which were stronger when vaporized. These data can inform regulatory and clinical decisions surrounding the use of cannabis among adults with little or no prior cannabis exposure.

Vaporized pot means a higher high Acute Effects of Smoked and Vaporized Cannabis in Healthy Adults Who Infrequently Use CannabisA Crossover Trial


Tory R. Spindle, PhDEdward J. Cone, PhDNicolas J. Schlienz, PhD; et al;John M. Mitchell, PhDGeorge E. Bigelow, PhDRonald Flegel, MSEugene Hayes, PhD, MBA; and Ryan Vandrey, PhD.

Vaporized pot means a higher high Acute Effects of Smoked and Vaporized Cannabis in Healthy Adults Who Infrequently Use CannabisA Crossover Trial





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