Concurrent use and order of use of cocaine and alcohol: behavioural differences between users of crack cocaine and cocaine powder.

AIMS The study investigates patterns of cocaine use and alcohol use when these substances were taken on their own, the order of administration of alcohol and of cocaine when the two substances were taken together, and changes in the doses of alcohol and of cocaine when the two substances were taken together. The study further investigates differences in the combined use of the two substances by users of cocaine powder and crack cocaine. DESIGN Entry criteria for the study were current (previous 30 days) use of both alcohol and cocaine. Study participants (n = 102) were recruited from clinical and non-clinical settings. Data were collected by face-to-face structured interviews. FINDINGS Different patterns of combined cocaine and alcohol use were reported by cocaine powder and crack cocaine users. Cocaine powder users tended to take increased doses of both cocaine and alcohol when these were used in combination. During high-dose crack using episodes, crack users tended to drink lower amounts of alcohol than usual. Cocaine powder users tended to use cocaine and alcohol concurrently. Crack users tended to use alcohol at the end of crack-using sessions. CONCLUSIONS The observed differences are not understood clearly but may be influenced by differential effects of route of administration upon absorption, bioavailability and the balance of euphoric/dysphoric effects. Research studies of the combined use of cocaine and alcohol should distinguish explicitly between the use of cocaine by different routes of administration, and this should be specified in the description of subject samples.