Detection of benzodiazepines in human hair by radioimmunoassay

OBJECTIVE: In this preliminary investigation, we sought to determine whether a standard benzodiazepine radioimmunoassay (RIA) could detect three benzodiazepines in human hair. DESIGN: Hair samples of 20-50 strands (minimum 10 mg) were cut from eight patients receiving diazepam, two patients receiving alprazolam, three patients receiving lorazepam, and two negative controls. Samples were treated with ethanol and phosphate buffer washes at 37 degrees C to remove external contamination. The protein hair matrix was destroyed using proprietary procedures, then analyzed with Abuscreen RIA designed to detect various benzodiazepines and their metabolites, using oxazepam as a reference standard. SETTING: Patients were hospitalized in a locked psychiatric facility. PATIENTS: Twelve patients with chronic psychiatric conditions who had received therapeutic dosages of benzodiazepines for 1-11 months were included in the sample. One outpatient who reported heavy prior diazepam use was also included. MAIN OUTCOME MEASURE: Detection of benzodiazepines was well above a 1.5 ng/10 mg cutoff level with the Abuscreen assay. RESULTS: Diazepam was readily detected, but alprazolam and lorazepam were not detected. CONCLUSIONS: There is no test that can currently determine duration and extent of prior benzodiazepine use. Hair analysis for diazepam offers a potential, new clinical and research tool for characterizing prior level and extent of usage.