Same, but different: Development and application of enantioselective methods in pharmaco-toxicological analysis

Since more than fifty years, researchers’ understanding of chiral compound chemistry has been increasing and becoming ever more important in the pharmaceutical and biochemical sectors. Indeed, the existence and the peculiar properties of chiral substances is one of the most evident and valuable examples of how specific, apparently minor physical-chemical properties can have a huge impact on the biological interactions of molecules. It is now well established that the enantiomers of, e.g., a drug substance can produce widely different clinical effects, and that a single enantiomer can be responsible for the full therapeutic effect, or the full toxicity, of a racemic mixture. Obviously, intermediate cases can also exist, where one enantiomer is slightly, or much, less active than the other, or has different biological effects¹. Acknowledging this situation, every new active pharmaceutical ingredient (API) having a chiral nature must be treated as if the optical isomers were altogether different molecules, unless the manufacturer can demonstrate that no significant differences exist in their pharmacodynamic and pharmacokinetic characteristics. Therefore, enantioselective analytical methods have become one of the staples in the study of new APIs and drug candidates, as well as in the toxicological and forensic fields. Some interesting applications of enantioselective separations are presented herein. Examples are made of both liquid chromatography (LC) separations using polysaccharide-based chiral stationary phases (CSPs), and of capillary electrokinetic chromatography (CEKC) separations using cyclodextrins (CDs) as chiral pseudo-stationary phases. These methods were developed for the chiral determination of clenbuterol in miniaturised biological samples for pharmaco-toxicological purposes, and of amphetamine precursors in seized bulk samples for forensic investigations, with satisfactory enantioselective performance and applicability potential^2,3.

¹ M.M. Coelho, C. Fernandes, F. Remião, M.E. Tiritan, Molecules 26 (2021) 3113.
² M. Protti, P.M. Sberna, R. Sardella, T. Vovk, L. Mercolini, R. Mandrioli, J. Pharm. Biomed. Anal. 195 (2021) 113873.
³ M. Protti, R. Mandrioli, J. Gonzalez-Rodriguez, L. Mercolini. J. Chrom. Open 2 (2022) 100032.