Cocaine: patterns of use, route of administration, and severity of dependence.

We contacted and interviewed 150 cocaine users in south London community settings. Most were taking cocaine regularly, but not daily, and in substantial doses. Three main routes of administration were used: smoking (40%), intranasal (32%), and injecting (24%). Injectors reported having used cocaine more frequently, in higher doses and for longer periods of time. Despite their frequent and extensive use of cocaine, the overall level of dependence was low for the great majority of the sample. Two-thirds (66%) of the full sample (and two-thirds (65%) of the crack smokers) reported only minor signs of dependence during the year prior to interview. Route of drug administration was related to severity of dependence. Cocaine taken by injection was associated with the highest levels of dependence; intranasal use was associated with the lowest levels, and crack smoking was intermediate between the two. There had been substantial changes in the initial route by which cocaine was used, with a clear trend away from injection on the first occasion of use. Those who first used cocaine before 1986 were more likely to have used the drug either intranasally or by injection. Cocaine users who first tried the drug after 1987 were increasingly likely to take it by smoking crack. Women and black (predominantly Afro-Caribbean) subjects were more evident in this sample of cocaine users than has previously been reported in many UK studies.