Development and pilot validation of computer-assisted self-infusion of ethanol (CASE): a new method to study alcohol self-administration in humans.

BACKGROUND

Human alcohol self-administration studies employing oral intake are subject to high variability of the resulting blood alcohol concentrations because of idiosyncrasies of gastrointestinal absorption kinetics among subjects. We sought to improve the subjects' opportunity to control their brain alcohol exposure by computer-assisted i.v. self-administration.

METHODS

Instead of drinking, subjects could request increments of their arterial blood alcohol concentration (aBAC) of precisely 7.5 mg% at any time they wanted by pressing a button, provided their aBAC would not exceed 100 mg%. The latency between pushing the button and reaching the new aBAC peak was preset to be 2.5 minutes on the first day and was randomly changed to 1.5 or 3.5 minutes on days 2 and 3 in a crossover design. The necessary rate and amount of alcohol infusion was calculated by the software about once every second. Nine healthy social drinkers (4 females/5 males; mean age 25.0 +/- 4.0 year) participated in 3 sessions each. Outcome measures were mean and maximum observed aBAC, and the number of alcohol requests.

RESULTS

Maximum aBAC was 76.5 +/- 26.3 mg% on average over all experiments. When grouping days 2 and 3 according to latency (1.5 vs. 3.5 minutes), maximum aBAC and the number of requests in the session were significantly higher with the faster rise and all 3 outcome measures were significantly correlated between days. No such correlations were found between the first and either of the following days.

CONCLUSIONS

These data suggest that CASE is practical and safe, and results in considerable alcohol exposure that can be manipulated with parameters chosen for the incremental exposure. Following 1 practice day, test-retest stability was good, suggesting a potential for use in scientific studies.