7-Aminoclonazepam is superior to clonazepam for detection of clonazepam use in oral fluid by LC–MS/MS

Abstract Background Clonazepam (CLON) is not only frequently prescribed in addiction management but is also commonly abused. Therefore many addiction clinics perform oral fluid (OF) testing, which unlike urine is not subject to adulteration, to monitor CLON compliance. However, CLON and other benzodiazepines can be challenging to detect in OF due to their weakly acidic nature and their presence in low concentrations. We determined the optimal technical and clinical approach for the detection of CLON use using OF. Methods We measured CLON and its primary metabolite 7-aminoclonazepam (7AC) by liquid chromatography–tandem mass spectrometry in OF specimens over a 2 month period. The samples were collected using the Orasure Intercept OF sample collection device. Results One hundred samples were presumptive-positive for 7AC and/or CLON. 91 (91.0%) confirmed positive for 7AC (median, range: 4.2, 0.5–316.7 ng/ml) using the ion ratio test, while only 44 of the 100 (44.0%) samples confirmed positive for CLON (median, range: 3.7, 0.5–217.2 ng/ml) using the ion ratio test. In OF the levels of 7AC were approximately 2.4-fold higher than CLON. The use of 7AC as an analyte for the detection of both CLON compliance and undisclosed use is also recommended. Conclusions 7AC should be the analyte measured in OF for the detection of CLON use.