INVESTIGATOR: Donald Abrams, M.D.
STUDY LOCATION: University of California, San Francisco
PROJECT TITLE: Vaporization as a "Smokeless" Cannabis Delivery System
PROJECT TYPE: Clinical Study
The full results of this study have been published in the journal Clinical Pharmacology & Therapeutics. Below is a brief summary of these results.
The purpose of this study was to evaluate the use of a vaporization system (the Volcano; VAPORMED® Inhalatoren) as a “smokeless” delivery system for inhaled marijuana. The study looked at heating marijuana to form a vapor and then comparing drug levels in the blood to those obtained from smoking an identical amount of marijuana from a cigarette. In addition, we compared the tolerability of the two methods and measured expired carbon dioxide to evaluate whether the vaporizer reduces exposure to respiratory toxins.
Eighteen healthy subjects were recruited and admitted to the inpatient ward of the General Clinical Research Center (GCRC) at San Francisco General Hospital to investigate the delivery of marijuana by vaporization compared to marijuana smoked in a standard cigarette. One dose (1.7, 3.4, or 6.8% tetrahydrocannabinol) and delivery system (smoked marijuana cigarette or vaporization system) was randomly assigned for each of the six study days. The analysis suggests that the blood levels of vaporized marijuana are similar to those of smoked marijuana. However, blood concentrations at 30 minutes after drug administration and beyond were significantly higher in vaporized marijuana as compared to smoked marijuana. In addition, the carbon monoxide levels were significantly reduced with vaporization compared with smoked marijuana. Fourteen participants preferred vaporization, 2 smoking, and 2 reported no preference. No adverse events were observed.
In this study, vaporization of marijuana was found to be a safe mode of delivery. Participants had a clear preference for vaporization over smoking as a delivery system for the marijuana used in this trial.
The Institute of Medicine report on Marijuana as Medicine published in 1999 concluded that "scientific data indicate the potential therapeutic value of cannabinoid drugs, primarily THC, for pain relief, control of N & V, appetite stimulation; smoked marijuana, however is a crude THC delivery system that also delivers harmful substances." The report recommended that clinical trials of cannabinoid drugs for symptom management should be conducted with the goal of developing rapid onset, reliable, and safe delivery systems.
Our primary objective in this study is to evaluate the use of a vaporization system (the Volcano; VAPORMED® Inhalatoren; Tüttlingen, Germany; www.vapormed.de) as a "smokeless" delivery system for inhaled marijuana. We will compare plasma levels of delta-9-tetrahyrocannabinol (THC), cannabidiol, cannabinol, and metabolites, including 11-OH-THC, in healthy volunteers after smoking one 3.95% THC marijuana cigarette (using the Foltin puff procedure) to those obtained when the same individual inhales the vaporization product of the marijuana from an identical cigarette processed through the Volcano device. In addition to plasma levels, we will also compare the THC concentration over an 8-hour time period, the subjective high experienced by the patients, and clinical evidence of cannabis effect by evaluating conjunctival hyperemia and heart rate.
We will also compare the tolerability of the two methods of ingestion, and we will measure expired carbon monoxide to evaluate whether the vaporizer reduces exposure to respiratory toxins. Twelve participants will be admitted for a 2-day stay at the General Clinical Research Center (GCRC) at San Francisco General Hospital. They will be randomly assigned to either inhalation of products of a smoked marijuana cigarette or the vaporization products produced by use of the Volcano device. Blood for pharmacokinetic evaluations and measurement of physiologic and psychologic effects of cannabis will be conducted by the GCRC research nursing staff who have been involved in all of our cannabis clinical trials to date. On day 2 of the stay, participants will inhale the alternative product and the same measurements will be obtained. If this study demonstrates that vaporization of cannabis produces significant blood levels and physiologic effects with a tolerable side effect profile, the Volcano may provide a rapid onset, reliable and safe delivery system to be used in future effectiveness studies of medicinal cannabis.