New Synthetic Opioids: What Do We Know About the Mutagenicity of Brorphine and Its Analogues?

Since 2019, a growing number of structurally diverse, non-Fentanyl-related novel synthetic opioids (NSOs) have emerged, but little is still known on the toxic profile of several of the molecules belonging to this class. Regarding long-term toxicity, few studies have investigated the genotoxic potential of NSOs, and no genotoxic data at all are available for the subclass of Brorphine-like benzimidazolone opioids. To deepen and broaden our understanding of their toxicological profile, this study was aimed at evaluating the genotoxicity of Brorphine and four of its analogues (Orphine, Fluorphine, Chlorphine and Iodorphine) on human lymphoblastoid TK6 cells employing a flow cytometric protocol of the "In Vitro Mammalian Cell Micronucleus (MN) test". The results show a statistically significant MNi increase for Fluorphine, Chlorphine and Iodorphine, but not for Brorphine and Orphine, demonstrating for the first three the ability to induce chromosomal damage. Afterwards, Brorphine and Orphine were tested on TK6 cells also in the presence of an exogenous metabolic activation system (S9 mix) to consider the possible genotoxic hazard posed by their metabolites as well. Also, under this experimental condition, no statistically significant increase in the MNi frequency was detected.