Assessing the effect of patterns of cocaine and alcohol use on the risk of adverse acute cocaine intoxication.

INTRODUCTION AND AIMS Although, in the laboratory, most acute adverse effects of cocaine are dose-dependent and alcohol potentiates some of these effects, there are few observational studies, and scarce awareness that the risk of acute cocaine intoxication (ACI) can increase as the amounts of cocaine and alcohol consumed increase. Our objectives were to assess if the risk of ACI increases with the level cocaine use, both in chronic and binge use; and also to determine whether it increases when a cocaine binge is combined with binge drinking or with regular excessive drinking. DESIGN AND METHODS Hypotheses were evaluated using logistic regression and case-crossover analyses in a sample of 720 young regular cocaine users who did not regularly use heroin, recruited at drug scenes in 2004-2006. All data on ACI, predictor and confounding variables were obtained through a computer-assisted personal interview. RESULTS The annual prevalence of ACI was 21%. In the last year 10.3% of the participants reported cocaine binges (≥ 0.5 g in 4 h). ACI risk increased considerably in the 4 h following a cocaine binge (odds ratio = 34.6; 95% confidence interval 11.5-170.8). Also, it increased with increases in the average level of cocaine used over a long period and when users regularly drank excessively. Finally, the results suggest that the high risk of ACI associated with cocaine binge may increase even more when combined with binge drinking. DISCUSSION AND CONCLUSIONS Awareness of the dose-dependent effect of cocaine on ACI risk, as well as the possible synergistic effect of alcohol, ought to be incorporated into preventive and care strategies.