Vaping Δ⁹-tetrahydrocannabinol (Δ⁹-THC) in liquid forms: pharmacokinetics, pharmacodynamics, and regulatory implications

Introduction: Little is known about the pharmacokinetics (PK) and pharmacodynamics (PD) of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) when vaped in liquid formulations. As the prevalence of vaping Δ⁹-THC in liquid forms grows, understanding the factors that influence PK/PD profiles is critical to guide future research and cannabis regulation. Areas covered: Currently, no human studies have elucidated the PK/PD profile of Δ⁹-THC from vaped liquids, as confirmed by searches of PubMed and Embase. Using existing research on smoked cannabis and nicotine-containing e-cigarettes, this review examines the potential influence of product potency, vaporization efficiency, consumer use behaviors, aerosol bioavailability, and other constituents on the PK/PD profile of Δ⁹-THC vaped in liquid forms. Further, we hypothesize whether PK/PD of Δ⁹-THC in liquid forms may differ from smoked cannabis and address potential regulatory implications (United States-focused) of novel vaping products. Expert opinion: While more potent than smoked cannabis, vaped liquid formulations with Δ⁹-THC may have a similar PK/PD profile through modulation of Δ⁹-THC delivery by consumer use behaviors. Potential health effects of high-potency vaping products with Δ⁹-THC in liquid form need to be carefully studied. Lastly, researchers should continue to think creatively about how this important work can progress, while restrictions on Δ⁹-THC continue to hinder research.