Cigarette smokers self-administer intravenous nicotine.

Human volunteers who smoked cigarettes were given the opportunity to press a lever that resulted in intravenous injections of saline or nicotine. Nicotine injections were taken in orderly patterns that were related to unit dose, whereas patterns of saline injections varied widely. Furthermore, the volunteers reported that nicotine produced subjective effects similar to those produced by administration of abuse drugs such as morphine or cocaine.