The aim of the present study was to see whether people with a known history of illicit drug abuse (IDRUG) shift towards benzodiazepines, zolpidem and zopiclone (BZD-Z) when they have to prove their abstinence from IDRUG.

We analysed 133 hair samples originating from persons in illicit drug AMPs (abstinence monitoring programs). Regranting of driver's licence was the most common motivation for proof of abstinence. To test a shift in drug consumption, hair samples of 87 cases (65 %) with request to analyse for IDRUG were additionally analysed for BZD-Z. The BZD-Z method includes 19 benzodiazepines and Z-drugs. In 46 of the cases (35 %) both IDRUG and BZD-Z analysis was requested by the public principals. An extraction suitable for illicit drugs and BZD-Z was used: 50 – 100mg hair is washed with water, isopropanol and acetone 4mL each and cut into small pieces. Then 20mg of washed hair is pulverised in a ball mill and internal standards are added. Extraction is done by addition of 1.5mL of a 1:1 mixture of formiate buffer (200mM pH 5) and methanol followed by overhead shaking during at least four hours. After centrifugation the liquid is separated and evaporated using nitrogen. The dried sample is reconstituted with 500μL water for injection into the LC-MS/MS system consisting of a Dionex ultimate 3000 HPLC equipped with a Phenomenex kinetex XCB 50 x 2,1mm and an AB Sciex 4000 Qtrap mass spectrometer operated in MRM mode. Analysis of ethylglucuronide (EtG) was performed only on special request.

In 91 (68 %) of the 133 cases none of the investigated substances (IDRUG, BZD-Z, EtG) were found. In 42 (32 %) of the cases 1 – 6 substances were detected. No BZD-Z analysis was ordered in 87 cases – thereof low and medium BZD-Z concentrations were found in 8 (9 %) cases. In 4 of these cases a regular consumption has to be considered. An additional BZD-Z analysis was ordered in 46 cases. 8 (19 %) samples tested positive. The hair concentrations in 3 cases implicated a regular ingestion. Most frequently detected BZD-Z substances were diazepam and its derivatives and zolpidem, followed by lorazepam and midazolam.

When looking just at previously defined analytes in AMPs, we conclude that potentially addictive BZD-Z consumption will remain undiscovered in a few cases. It is therefore crucial for road safety that road traffic examination is performed by specially trained medical staff. In the field of traffic medicine, physicians and psychologists are trained to recognise addictive behaviour, which helps to reduce the probability of inadequate AMP settings.