URINE BENZODIAZEPINES SCREENING OF INVOLUNTARILY DRUGGED AND ROBBED OR RAPED PATIENTS

Objective: This study involved 35 patients who claimed to have been dr ugged before being robbed or raped, despite urine negative toxicologic screening by immunoenzymatic methods. The urines were frozen for furt her investigations, including enzymatic hydrolysis of urinary conjugat es, liquid-solid extraction and, finally, immunoenzymatic screening of concentrated urine extract. Methods: Urine benzodiazepines were analy zed by immunoenzymatic assay before and after enzymatic hydrolysis com bined with extraction. Results: On direct immunoenzymatic screening, 1 7 of the 35 urine samples were benzodiazepine positive. Enrichment of preserved specimens improved the detection threshold from 200 ng/mL to 50 ng/mL and 10 of the 18 negative urines became positive. Conclusion : This method allowed us to demonstrate the benzodiazepines in half of previously negative urine samples. Benzodiazepine screening is partic ularly problematic because of low dosage, rapid elimination, failure t o detect conjugated metabolites by immunoenzymatic reagents and high t hreshold of sensitivity for certain substances.