Different effect of codeine/paracetmol on driving performance in a monotomous surrounding as a function of age

Introduction Epidemiological studies revealed that drug consumption is suspected to increase the risk of driving accidents. Among drugs, the association of codeine/paracetamol who is considered one of the most effi cient to ease pain as compared to other analgesics of level II in the WHO classifi cation, could decrease vigilance and thus impair driving performance. However, few experimental study evaluated codeine effects on driving, and they only tested these effects on young healthy drivers whereas elderly people represent a large part of drivers and are used to consume this type of drugs. The objective of the present communication is to compare the behavioural effect of therapeutic dose of codeine/paracetamol on simulated driving in subjects of different age.

Methods The effects were evaluated in two groups of 16 subjects, young (2030 years) and aged (55 to 65 years). One hour of monotonous driving performance was evaluated after 1 dose of codeine/ paracetamol (20mg/400mg) intake and compared to a placebo in a double blind and balanced design. Pills were taken at 8AM, monotonous driving task was performed with a monoscreen driving simulator one hour after at the theoretical plasma peak concentration of the drug. Participants had to keep a constant speed of 110km/h and a stable trajectory in the center of the right place. Standard deviation of both the lateral position and the speed, the number of road exits were analysed. Plasmatic concentration of codeine, morphine and paracetamol were determined at the beginning and at the end of the experiment.

Results They showed that the minimal therapeutic dose of codeine/ paracetamol used here differently affect driving performance in function of age. Young subjects performances did not vary after drug intake whereas aged subjects performance were impaired. In particular aged subjects standard deviation of lateral position on the lane (SDLP), which is considered as the most sensitive parameter to investigate durgs effects, increased after the minimal therapeutic dose of codeine/paracetamol. Moreover, aged subjects seemed to eliminate the drug more slowly than young subjects. These results are in agreement with our past study on the effects of zolpidem revealing that this hypnotic which did not appear at risk for driving in healthy young subjects could be at risk for aged subjects. These results underline the necessity to evaluate the effects of drugs in several aged range.