Model-based analysis on systemic availability of co-administered cannabinoids after controlled vaporised administration.

BACKGROUND: The most important two medicinal cannabinoids are Δ9 -tetrahydrocannabinol (THC) and cannabidiol (CBD). Vaporised administration is superior due to its higher systemic availability, lower individual variability and faster drug delivery. Although it is common THC is co-administered with CBD, the influence of CBD on the pharmacokinetics, especially the systemic availability of THC after vaporised administration, is unknown. AIMS: To investigate the influence of different doses of co-administered CBD on the systemic availability of THC, and to compare the availability of THC and CBD in a sample of frequent and infrequent cannabis users. METHODS: The study used a randomised, double-blind, crossover placebo-controlled design. THC and/or CBD in ethanol was vaporised and inhaled. Plasma concentrations of THC and CBD were analysed. The THC data created in this study were pooled together with published THC pharmacokinetic data in order to cover all the phases of THC disposition. Population pharmacokinetic model of THC was developed based on the pooled data. The model of CBD was developed based on the data created in this study. RESULTS: Population pharmacokinetic models of THC and CBD were developed. With concomitant inhalation of high-dose CBD, the systemic availability of THC decreased significantly. Frequent cannabis users appeared to have higher systemic availability of THC and CBD when high-dose CBD was administered. CONCLUSIONS: The results observed in this study are useful for guiding future pharmacokinetic studies of medicinal cannabinoids, and for development of dosing guidelines for medical use of cannabis in the 'real-world' setting.

Second-Hand Exposure of Staff Administering Vaporised Cannabinoid Products to Patients in a Hospital Setting.

BACKGROUND: In many health settings, administration of medicinal cannabis poses significant implementation barriers including drug storage and safety for administering staff and surrounding patients. Different modes of administration also provide different yet potentially significant issues. One route that has become of clinical interest owing to the rapid onset of action and patient control of the inhaled amount (via breath timing and depth) is that of vaporisation of cannabinoid products. Although requiring a registered therapeutic device for administration, this is a relatively safe method of intrapulmonary administration that may be particularly useful for patients with difficulty swallowing, and for those in whom higher concentrations of cannabinoids are needed quickly. A particular concern expressed to researchers undertaking clinical trials in the hospital is that other patients, nurses, and clinical or research staff may be exposed to second-hand vapours in the course of administering vaporised products to patients. OBJECTIVE: The objective of this study was to take samples from two research staff involved in administering vaporised Δ9-tetrahydrocannabinol to participants in a clinical trial, to examine and quantitate cannabinoid presence. METHODS: Blood samples from two research staff were taken during the exposure period for three participants (cannabis users) over the course of approximately 2.5 h and analysed using tandem mass spectrometry. RESULTS: Blood samples taken over a vaporised period revealed exposure below the limit of detection for Δ9-tetrahydrocannabinol and two metabolites, using tandem mass spectrometry analytical methods. CONCLUSIONS: These results are reassuring for hospital and clinical trial practices with staff administering vaporised cannabinoid products, and helpful to ethics committees wishing to quantify risk.