No abstract

Background and objective: Changes in cannabis legalization regimes in several countries have influenced the diversification of cannabis use. There is an ever-increasing number of cannabis forms available, which are gaining popularity for both recreational and therapeutic use. From a therapeutic perspective, oral cannabis containing Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) is a promising route of administration but there is still little information about its pharmacokinetics (PK) effects in humans. The purpose of this systematic review is to provide a general overview of the available PK data on cannabis and THC after oral administration. Materials and Methods: A search of the published literature was conducted using the PubMed database to collect available articles describing the PK data of THC after oral administration in humans. Results: The literature search yielded 363 results, 26 of which met our inclusion criteria. The PK of oral THC has been studied using capsules (including oil content), tablets, baked goods (brownies and cookies), and oil and tea (decoctions). Capsules and tablets, which mainly correspond to pharmaceutical forms, were found to be the oral formulations most commonly studied. Overall, the results reflect the high variability in the THC absorption of oral formulations, with delayed peak plasma concentrations compared to other routes of administration. Conclusions: Oral THC has a highly variable PK profile that differs between formulations, with seemingly higher variability in baked goods and oil forms. Overall, there is limited information available in this field. Therefore, further investigations are required to unravel the unpredictability of oral THC administration to increase the effectiveness and safety of oral formulations in medicinal use.

Recently, several countries authorized the use of cannabis flowering tops (dried inflorescences) with a standardized amount of Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD) and their acidic precursors [Δ-9-tetrahydrocannabinolic acid A (THCA-A) and cannabidiolic acid (CBDA)] to treat neurogenic pain. We studied the acute pharmacological effects and disposition of cannabinoids and their metabolites in serum, oral fluid, sweat patch and urine of 13 healthy individuals treated with medical cannabis decoction and oil. Cannabinoids and their metabolites were quantified by ultrahigh performance tandem mass spectrometry. Even if the oil contained a significantly higher amount of THC, the absorption of THC and its metabolites were similar in both herbal preparations. Conversely, whereas oil contained a significantly higher amount of CBD and a lower amount of CBDA, absorption was significantly higher after decoction intake. Only cannabinoids present in both herbal preparations (THC, CBD, THCA-A and CBDA) were found in oral fluid, due to the higher acidity compared with that of serum. THC metabolites urinary excretion was always higher after decoction administration. Decoction induced greater feeling of hunger and drowsiness than oil preparation. Pharmacokinetics of cannabinoids, their precursors and their metabolites in biological fluids of individuals treated with cannabis decoction and oil showed a high interindividual variability. The aqueous preparation was generally better absorbed than the oil, even if it contained a minor amount of THC, THCA-A and CBD.