Driving under the influence of gamma-hydroxybutyrate (GHB).

We used an in-house forensic toxicology database (TOXBASE) to evaluate the occurrences of gamma-hydroxybutyrate (GHB) in blood samples from people arrested in Sweden for driving under the influence of drugs (DUID) between 1998 and 2007. Age, gender, and concentrations of GHB in blood were compared and contrasted when GHB was the only drug present and when it occurred along with other drugs. GHB was determined in blood by gas chromatography (GC) after conversion to gamma-butyrolactone (GBL) and analysis of the latter with a flame ionization detector. The cut-off concentration of GHB in blood for reporting a positive result was 8 mg/l, which served as limit of quantitation. The mean and median GHB concentrations were 89 mg/l and 82 mg/l, respectively (2(1/2) and 97(1/2) percentiles 12 and 220 mg/l) in 548 arrested drivers. These individuals were predominantly men (95%) with an average age of 26 +/- 5.5 years (range 15-50 years) and women (5%) were several years older with an average age of 32 +/- 8.0 years (range 19-47). There were 102 individuals (29%) who were arrested more than once with GHB in blood (average approximately 3 times per person) and one as many as 10 times. GHB was the only psychoactive substance detected in 215 cases (39%) at mean and median blood-concentrations of 91 mg/l and 83 mg/l, respectively. These concentrations were not significantly different from poly-drug users. A weak but statistically significant correlation existed between the concentration of GHB in blood and the person's age (N = 548, r = 0.135, P < 0.01). The signs of drug influence noted by arresting police officers included sedation, agitation, unsteady gait, slurred speech, irrational behavior, jerky body movements, dilated pupils, and spitting. The blood concentrations reported here are probably appreciably less than at time of driving (30-90 min earlier) owing to the short elimination half-life of GHB (t ((1/2)) = 30-40 min).