Driving under the influence of drugs (DUID) is a serious global problem and poses a public health risk. With new psychoactive substances (NPS) entering the illicit drug market several years ago, a significant number of highly potent and harmful drugs have become easily available and the use of these substances may impair a person's ability to drive a vehicle safely. Since NPS are not usually covered in routine toxicological analyses used in DUID investigations, only little is known about their prevalence. To gather more information on the prevalence of NPS in cases of impaired driving, a retrospective study was conducted to determine the prevalence of these drugs in blood samples of DUID suspects in southern Germany. A total of 837 blood samples, which were collected in the German federal states Baden-Württemberg and Bavaria in 2017 and 2018, were reanalyzed for designer stimulants and synthetic cannabinoids by liquid chromatography-quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). For the analysis of synthetic cannabinoids, a more sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) screening method was additionally used. A total of 14 cases (1.6%) tested positive for NPS. Designer stimulants were detected in two cases (0.2%) and synthetic cannabinoids were found in 12 cases (1.4%). The rather low prevalence rate of 1.6% estimated in this study suggests that driving under the influence of NPS does not play a large role in southern Germany. Nonetheless, in all cases in which the psychophysical impairment cannot be explained by routine toxicological findings, a screening for NPS should additionally be performed.

Phosphatidylethanol (PEth) has become a widespread marker offering an up to four weeks retrospective window to detect alcohol use. Due to the COVID 19 pandemic, ethanol-based hand sanitizers are frequently used. The aim of this study was to develop and validate a method for determination of up to seven different homologues of PEth from dried blood spots (DBS) after use of an ethanol-based hand sanitizer. Objectives of its preliminary application were to prove whether a threshold of 20 ng/mL for PEth 16:0/18:1 is reached and whether other homologues are formed as well as if positive findings of urinary ethyl glucuronide (UEtG) can be observed with respect to assess monitoring of abstinence control programs. Ten volunteers (8 occasional, 2 regular drinkers) were recruited to excessively use an ethanol-based hand sanitizer on 5 successive days. Dried blood spots and urine samples were collected daily. PEth and UEtG were determined by LC-MS/MS. In total, two volunteers with initial PEth 16:0/18:1-concentrations of 19.3 and 14.6 ng/mL exceeded the threshold of 20 ng/mL six times. Regular drinkers had starting PEth 16:0/18:1-concentrations of 242 and 354 ng/mL, showing a decline of PEth-concentrations in six out of the seven homologues over five days. In teetotalers, formation of PEth species could not be observed. Thus, not satisfying requirements in an alcohol monitoring program with initial PEth-negative blood cannot be explained by a frequent use of ethanol-based hand sanitizer only. In cases of regular alcohol consumption, PEth-homologues are not likely to be further influenced. However, results indicated that individuals with a PEth-concentration close to 20 ng/mL are at risk of exceeding the threshold by using ethanol-based hand sanitizer.

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Aims Phosphatidylethanol (PEth) is only formed when ethanol is present in blood. This direct alcohol marker has been widely discussed, including the minimum amount of ethanol being necessary to form as much PEth as to exceed the threshold of 20 ng/mL in previously PEth negative subjects. In order to corroborate hitherto existing results, a drinking study including 18 participants after a 3-week alcohol abstinence was performed. Methods They consumed a pre-calculated amount of ethanol to reach a blood alcohol concentration (BAC) of at least 0.6 g/kg. Blood was drawn before and periodically seven times after alcohol administration on day 1. Blood and urine were also collected the next morning. Dried blood spots (DBS) were prepared immediately from collected venous blood. BAC was determined by head space gas chromatography and the concentrations of both PEth (16:0/18:1, 16:0/18:2 and five additional homologues) and ethyl glucuronide (EtG) were analysed using liquid chromatography–tandem mass spectrometry. Results Out of 18, 5 participants had concentrations of PEth 16:0/18:1 above the threshold of 20 ng/mL, and 11 out of the 18 subjects had concentrations between 10 and 20 ng/mL. In addition, four persons had PEth 16:0/18:2 concentrations above 20 ng/mL the following morning. All test subjects tested positive for EtG in DBS (≥ 3 ng/mL) and urine (≥100 ng/mL) upon 20–21 h after alcohol administration. Conclusion By combining both a lower cutoff of 10 ng/mL and the homologue PEth 16:0/18:2, the sensitivity to detect a single alcohol intake after a 3-week abstinence increases to 72.2%.