Optimized administration of THC for clinical use by vaporizing

Arno Hazekamp, Renee Ruhaak, Lineke Zuurman, Joop van Gerven, Rob Verpoorte
Division of Pharmacognosy, Institute of Biology, Leiden University, The Netherlands
Center for Human Drug Research, Leiden, The Netherlands

What is currently needed for optimal use of medicinal cannabinoids is a feasible, non-smoked, rapid-onset delivery system. Smoking of cannabis plant material results in the highest bioavailability and consequently pulmonal administration of cannabinoids is considered to be very effective. The goal of this study was to evaluate the performance of the Volcano vaporizer in terms of reproducible administration of pure THC, without the formation of degradation products. Results were used for designing a clinical trial for administration of THC by vaporizing.

Methods: Using the Volcano cannabis vaporizer, THC and its acidic analogue THCA were tested for delivery of THC into the balloon of the Volcano device. The efficiency of vaporizing of these samples was compared with cannabis plant material. Analyses were performed using HPLC and quantitative 1H-NMR. After determination of the dynamics of heating up, and accuracy and stability of vaporizing temperatures of the Volcano, the temperature setting and balloon volume were systematically optimized for maximum evaporation of THC. Factors contributing to loss of THC were evaluated. Several Volcano set-ups were tested to determine variability. After validation, the Volcano was used in a methodology study to determine the effects of pulmonary administration of a rising dose of THC in twelve healthy volunteers, who were subjected to an array of physiological and psychological tests after each administration.

Results: Under optimized conditions the Volcano was found to deliver about 54% of the loaded sample in a reproducible way into the vapor phase without formation of degradation products like delta-8-THC or CBN. In the range of 2 to 8 mg of THC the delivery was found to be linear with the amount of THC loaded onto the vaporizer. Prolonged storage of the balloon before inhalation resulted in an increasing loss of THC by condensation. No significant differences in THC delivery were found between four devices tested. Full results of this phase I clinical trial are not presented here, but a clear dose-dependent effect was found in several of the used tests. During these inhalation studies the fraction of exhaled THC was found to be around 34%. Improvements in the original design of the Volcano were made based on these results for further optimization of the Volcano for administration of pure cannabinoids in a clinical setting.

Conclusions: Using the Volcano for pulmonal administration of THC, a delivery is reached that is comparable to smoking, without the presence of degradation products or harmful byproducts in significant amounts. This study confirms that the pulmonary administration of cannabinoids by evaporation certainly has a clinical potential. With the Volcano a safe and effective cannabinoid delivery system seems to be available to patients. Although our current study has concentrated on the delivery of THC it should be noted that other cannabinoids might also have a role to play for some indications.

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