FAST warmly congratulates Andriy Gorbenko on successfully defending his dissertation, *Clearing the Haze: Investigating the Clinical Pharmacology of Cannabinoids*, at Leiden University. The doctoral research was conducted at the Centre for Human Drug Research (CHDR), and the defense took place on June 11, 2026.

New clinical research shows that cannabidiol (CBD) does not reduce the undesirable effects of THC. In fact, a high dose of CBD (450 mg) significantly enhanced the psychoactive effects of oral THC—including the feeling of being “high”—and led to higher concentrations of THC and its active metabolite, 11-OH-THC, in the blood. Even lower doses of CBD (30 mg) increased exposure to THC. The researchers suspect that CBD inhibits the breakdown of THC via the cytochrome P450 enzyme system. Furthermore, no improvement in the analgesic effect of THC was observed. The results thus contradict the commonly held assumption that CBD can mitigate the adverse effects of THC and underscore the importance of considering potential drug interactions when CBD and THC are used concurrently.

The research was conducted under the supervision of advisor Prof. Dr. Geert Jan Groeneveld and co-advisors Jules Heuberger and Saco de Visser (scientific director of FAST). Although this study focused on the interaction between CBD and THC, the findings are also relevant to the broader development of therapies based on psychoactive substances. The research demonstrates how important it is to carefully assess the pharmacological interactions, efficacy, and safety of such substances.

This aligns well with FAST’s mission to accelerate the development of innovative, therapy-oriented applications of psychoactive substances, including psychedelics. This collaborative approach contributes to a solid scientific foundation for the development and sustainable implementation of new treatments.

More information
The full dissertation, *Clearing the Haze: Investigating the Clinical Pharmacology of Cannabinoids*, is available via CHDR. Download the dissertation here.