Method Development for the Detection of Synthetic Cathinones and Investigation of Their Metabolism Using Human Microsomes

Abstract

Abuse of designer drugs such as synthetic cathinones presents a challenge to both medical and forensic experts. Detecting cathinone exposure in humans requires a sensitive, reliable method and treatment involves an understanding of the physiological response of the body to these novel compounds. This study focused on developing a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the detection and quantitation of sixteen popular synthetic cathinone analogues. The method was found to be linear from a lower limit of 1ng/ml-10ng/ml, depending on the drug, to an upper limit of 25ng/ml for all tested drugs. This LC-MS/MS method was then employed to study the interaction of specific bath salts, mephedrone (MEPH) and buphedrone (BUPH), with cytochrome p450 (CYP) enzyme systems. The IC50s of MEPH and BUPH were determined to be 10.1 �M and 61.7 �M, respectively, using a fluorescence-based CYP2D6 inhibitor screening kit, demonstrating an inhibiting interaction with CYP2D6. A human liver microsomal preparation consisting of 20 Phase I metabolic enzymes was then tested with MEPH and BUPH, which demonstrated no significant change in parent compound concentration over the course of an hour. These findings suggest that MEPH and BUPH act as a CYP2D6 inhibitors, but are not metabolized as a substrate by the enzymes in the test system.