The REMEDi HS system is a broad-spectrum drug identification system designed for emergency toxicology screening and forensic applications, and total analysis time is about 20 minutes. The system has a software routine that uses an internal standard to perform quantitative analysis for target compounds when calibrators are available. Further, response factors are supplied for rapid estimates of drug concentrations when calibrators are not available. The present study of drug concentrations showed that slopes of regression lines between the rapid estimate method and the internal standard method were generally within 20 percent of unity, in agreement with manufacturer claims. Semiquantitative estimates based on the response factor method also showed good agreement with results obtained using multipoint calibration. The estimates were sufficient for clinical differentiation of routine and toxic drug levels. Study findings demonstrated that the REMEDi HS system is particularly useful in rapidly estimating drug concentrations in emergency case samples when calibrators are not readily available and that the system can be used for the therapeutic monitoring of ranitidine, bromisovalum, lidocaine, and diphenhydramine. 21 references, 3 tables, and 3 figures