Hexahydrocannabinol Pharmacology, Toxicology, and Analysis: The First Evidence for a Recent New Psychoactive Substance

Background: During the last two years, hexahydrocannabinol (HHC), the hydrogenated derivative of tetrahydrocannabinol has been freely sold by internet websites as a “legal” replacement to THC and cannabis in a range of highly attractive branded and unbranded products, some of which are sold as “legal highs”. Potentially, there could be a large demand for HHC products by individuals in Europe and internationally. Methods: Studies reporting HHC pharmacology, toxicology and analysis were identified from Pubmed and Scopus databases, and official international organizations’ websites were considered. Results: HHC showed the effects of the typical cannabinoid on the central nervous system, with lower potency than Δ⁹-THC. A few studies highlighted that 9(R)-HHC is more potent than 9(S)-HHC. This molecule showed an affinity for cannabinoid receptor CB1 both in vitro and in vivo, suggesting a possible therapeutic effect in several pathologies. However, the affinity for the CB1 receptor suggests a possible addiction potential, inducing the users to misuse it. Since actual intoxication cases have not yet been reported, the HHC harmful potential was not described, probably due to the lack of effective analytical methods to detect HHC in biological matrices. Conversely, different analytical assays were developed and validated to separate HHC epimers in natural and non-natural sources. Conclusion: Similarly to other NPS, the HHC represents a cheaper alternative to the controlled Δ⁹-THC. Its monitoring is a crucial challenge for toxicological and forensic purposes. To this concern, it is essential to further investigate HHC to support health providers in the identification of related intoxications.