Conduite automobile et cocaïne : bases bibliographiques pour un consensus de la Société française de toxicologie analytique

Cocaine is the second-most consumed illegal drugs in France, after cannabis. It is mainly consumed by snorting (in hydrochloride form) or smoking (as a base). After absorption, cocaine is highly metabolized in two main metabolites, benzoylecgonine (BZE) and ecgonine methylester (EME). Assay methods are separative techniques either in liquid or gas chromatography coupled to a mass-spectrometry detection. It is highly recommended to measure cocaine and its main metabolites BZE and EME. Indeed, cocaine is relatively unstable in blood in vitro, and can be transformed into metabolites by the action of erythrocyte and plasmatic esterases. A sampling on 2.5% sodium fluoride blood tubes reduces the instability. For the same reason, samples should be conserved at -20 °C and not at +4 °C where degradation occurs after 48 hours. In the context of driving under influence, most countries quantify in whole blood but some chose plasma or serum. Under optimum conditions of conservation, cocaine will persist in blood for 3 to 8 hours, and up to 24 hours in the urine. The detection window is longer in chronic users. Benzoylecgonine is conventionally found up to 24 hours in the blood and between 40 and 60 hours in the urine. The cut-offs applied vary according to European countries. Some countries have only a cut-off for cocaine, such as France (50 μg/L), while many countries also have a cut-off for BZE, such as Belgium or Finland. It is now accepted that cocaine disrupts driving ability, but a danger threshold has not been clearly identified. Different experts recommended a threshold value of cocaine in the blood between 2 and 50 μg/L according to the countries from which the risk of having an accident or disturbed behavior is significantly increased. In France, the French Society of Analytical Toxicology (SFTA) proposed a threshold of 10 μg/L for cocaine. In most studies, the oral fluid concentrations of cocaine are higher than in blood, but there is no correlation between these two matrices. The effects of cocaine depend on the quantity consumed, the used route of administration, the subjects and related substances. Craving is a major component of addiction to cocaine. Complications can be very numerous, mainly cardiovascular type, but also pulmonary, ENT, neurological and psychiatric complications.