Determination of benzodiazepines in clinical serum samples: Comparative evaluation of REMEDi system, aca analyzer, and conventional HPLC performance

Emergency toxicology or drug screening in clinical settings requires rapid qualitative and quantitative analysis with acceptable levels of sensitivity and specificity. The aim of this study was to comparatively evaluate the p erformance of the multi-column HPLC-based REMEDi drug profiling system (Bio -Rad), the aca analyzer (Du Pont), and the bench standard conventional HPLC method in the identification of 12 clinically important benzodiazepines. I n this study, the presence of benzodiazepines in 133 patients' serum sample s were qualitatively and comparatively analyzed by these three procedures. Among these methods, 120 of 133 samples were identified as benzodiazepine-p ositive by conventional HPLC (90%); 127 by aca analyzer (95%); and 84 by RE MEDi (63%). Detection sensitivity of REMEDi for most of the benzodiazepines was found satisfactory when concentrations were greater than 1.0 mu g/mL. When benzodiazepine concentrations were in the ranges of 0.3-1.0 mu g/mL, d etection sensitivity became varied among the benzodiazepine family of drugs by REMEDi method. REMEDi procedure should not be considered as the method of choice for detection of benzodiazepines if expected concentration levels are below 0.3 mu g/mL, with the exception of bromazepam. Conventional HPLC displayed the highest sensitivity and specificity for the detection of ben zodiazepines. In our studies, 36 REMEDi-negative samples were positive by H PLC, although in 16 of the 36 REMEDi negative samples (13.3%), the presence of benzodiazepines was detected but only listed as candidates without posi tive identification of the individual compounds by REMEDi. In our series, h owever, there were no false positives by the REMEDi method whereas aca proc edure showed 13 false positive results (9%) and 6 cases of false negative ( 4%). Our data indicate that the REMEDi procedure can be used on serum samples fo r rapid qualitative screening of clinically important high levels of benzod iazepines with high specificity. However, due to the relatively low sensiti vity of REMEDi in samples with low benzodiazepine levels and relatively low specificity by aca, all samples should be further confirmed by conventiona l HPLC procedure. J. Clin. Lab. Anal. 13:106-111, 1999. (C) 1999 Wiley-Liss , Inc.