Blood GHB concentrations and results of medical examinations in 25 car drivers in Norway.

Purpose: information on the clinical effects associated with whole blood gamma-hydroxybutyrate (GHB) concentrations is sparse. We have investigated possible relationships between GHB blood concentrations and clinical effects in car drivers.
Methods: in Norway, the police stop car drivers suspected of drug-driving. Medical doctors perform a clinical test of impairment (CTI) and blood samples are screened for drugs/medicines by immunological, enzymatic and chromatographic methods at the Division of Forensic Toxicology and Drug Abuse. GHB is a part of our extended drug-testing programme. GHB is standardly measured as GBL by gas chromatographic method. All the results were stored in a database. This database was searched between 2000 and 2007 for car drivers positive only for GHB, called GHB-drivers. A control group with a completely negative blood analysis, including GHB, called control-drivers, was included in the study.
Results: twenty-five car drivers had only GHB in their blood. The police reported that 78% showed unsafe driving behaviour and seven were involved in car accidents, without serious injury. A total of 61% of the drivers were found to be sleepy or in an even more reduced state of consciousness. The median GHB blood concentration was 1,262 (range 592-2,191) μmol/L, measured a median of 69 min after the police had stopped the driver from driving. The GHB blood concentration tended to increase with increasing impairment and reduced consciousness. Clinical findings were normal- to large-sized pupils (86%), impairment as the final conclusion (84%), impaired balance/nystagmus (62 and 54%, respectively), congested/shiny conjunctiva (67%), apathetic, aggressive or abnormal behaviour (65%), reduced short-term memory (67%), reduced/absent pupillar reaction to light (65%), heart rate ≤ 70 beats/min (56%), and some level of reduced consciousness (56%). In the control-drivers, 15.6% were found by the medical doctors to have reduced consciousness or impaired.
Conclusions: the median GHB blood concentration of the 25 car drivers was high. Most drivers had clinical impairment that was not explainable by injuries, with depressive effects on the central nervous system and sympathomimetic effects on eyes. Effects on impairment and consciousness tended to be concentration-dependent. The number of drivers who were impaired or had reduced consciousness was highly increased in GHB-drivers compared to controls. Based on these results, we conclude that the GHB-drivers most probably drove in an unsafe manner due to impairment by GHB.