The effects of mixing alcohol and prescription drugs on driving and cognitive performance: A randomised simulator study.

INTERVENTION: Interventions consist of administration of the following substances in a randomised, counterbalanced order at each testing session: Arm 1: single oral dose of codeine 60mg (2 x 30mg tabs) Arm 2: single oral dose of oxazepam 30mg Arm 3: ethanol (target BAC=0.05g/100ml, dose=0.34g/kg) administered as a bolus oral dose to reach the target BAC (vodka mixed with orange juice in ratio of 1:3), followed by an intravenous infusion of 5% ethanol in 5% dextrose for the remainder of the study period to maintain the participant at a BAC of 0.05g/100ml. Participants are required to attend a total of 8 testing sessions, in a random order, comprising of the following conditions: Session 1 ‐ Placebo IV infusion + placebo codeine tablet + placebo oxazepam tablet Session 2 ‐ Placebo IV infusion + 60mg codeine tablet + placebo oxazepam tablet Session 3 ‐ Placebo IV infusion + placebo codeine tablet + 30mg oxazepam tablet Session 4 ‐ Ethanol IV infusion (0.34g/kg) + placebo codeine tablet + placebo oxazepam tablet Session 5 ‐ Ethanol IV infusion (0.34g/kg) + 60mg codeine tablet + placebo oxazepam tablet Session 6 ‐ Ethanol IV infusion (0.34g/kg) + placebo codeine tablet + 30mg oxazepam tablet Session 7 ‐ Placebo IV infusion + 60mg codeine tablet + 30mg oxazepam tablet Session 8 ‐ Ethanol IV infusion (0.34g/kg) + 60mg codeine tablet + 30mg oxazepam tablet A washout period of 72 hours between sessions is adopted in this study. CONDITION: To determine the extent to which commonly prescribed therapeutic doses of codeine and oxazepam, alone and in combination with a moderate dose of alcohol, cause measurable impairment of simulated driving ability and cognitive performance in healthy individuals. PRIMARY OUTCOME: Performances on an advanced driving simulator for each of the study intervention(s) combinations. Performance was measured on parameters of driving such as standard deviation of lateral lane position, mean travel speed, time‐to‐collision and traffic infringements. SECONDARY OUTCOME: Performances on higher order cognitive tests for each of the study intervention(s) combinations as measured by the OSPAT and CANTAB systems. INCLUSION CRITERIA: 1. Adequate cognition and English language skills to validly consent and complete study procedures 2. Holds a current drivers licence 3. Able to provide written informed consent