d-Amphetamine increases choice of cigarette smoking over monetary reinforcement

Rationale: Psychomotor stimulants previously have been found to increase th e frequency of cigarette smoking, but it is unclear whether this is due to a nonspecific increase in general activity or a specific increase in the re inforcing effects of smoking. Objectives: To investigate whether d-amphetam ine increases the relative reinforcing effects of cigarette smoking. Method s: Ninety minutes after d-amphetamine (7.5, 15 mg/70 kg) or placebo adminis tration, 13 male and female subjects participated in 3-h sessions during wh ich they could make a maximum of 20 choices between cigarette smoking (two puffs per choice), earning money ($0.25 per choice), or neither. In separat e sessions, using the same subjects, the effects of d-amphetamine on the fr equency of ad libitum smoking was assessed. Results: During choice sessions , d-amphetamine dose-dependently increased smoking choices from 4.2 +/-0.6 to 5.7 +/-0.6. During sessions in which subjects smoked ad libitum, d-amphe tamine increased number of cigarettes smoked from 2.8 +/-0.4 to 3.8 +/-0.6. Breath carbon monoxide (CO) levels, a measure of smoke exposure, showed co rresponding dose-related increases. Conclusions: These results are consiste nt with previous findings that d-amphetamine increases smoking and provide evidence that this effect is due to a drug-produced increase in the relativ e reinforcing effects of cigarette smoking.