Determination of illegally abused sedative-hypnotics in hair samples from drug offenders

Abstract

As several sedative-hypnotics are distributed illegally and are available domestically through media like the internet, their abuse is becoming a serious social problem. In the present study, four legal cases involving abuse of diazepam, midazolam, and/or zolpidem were proved by hair analysis using a simultaneous quantification method for the determination of diazepam (and its metabolites), lorazepam, midazolam, and zolpidem, which are often illegally abused in Korea, in hair that was developed and validated. Drugs and metabolites in hair were extracted using methanol followed by solid-phase extraction. The extracts were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and analyzed using gas chromatography-mass spectrometry in selected ion monitoring mode. The validation parameters of the method, including selectivity, linearity, limits of detection and quantification (LOQ), recovery, intra- and interassay precision and accuracy, and processed sample stability, were satisfactory. Moreover, the developed method was successfully applied to actual cases. In case 1, which involved a pop singer who was detained for suspected drug abuse, the concentrations of diazepam and nordiazepam were 5.7 and 2.0 ng/mg in nonpigmented hair and 6.6 and 1.8 ng/mg in pigmented hair, respectively. In case 2, 0.4 ng/mg zolpidem was detected in hair from a drug abuser who purchased illegally through the internet, and 0.2 ng/mg midazolam was detected in hair from an illegal drug seller in case 3. In case 4, diazepam (lower than the LOQ), nordiazepam (0.7 ng/mg), and zolpidem (0.7 ng/mg) were detected in hair from a medical doctor who abused drugs using forged prescriptions.