Do serotonin uptake inhibitors decrease smoking? Observations in a group of heavy drinkers

Serotonin uptake inhibitors have been reported to alter several consummatory and drug self-administration behaviors in rats. These observations suggest important therapeutic applications in humans. While evaluating zimelidine and citalopram effects on ethanol intake, we also assessed smoking behavior. Five male heavy drinkers smoking 29.7 +/- 9.0 (mean +/- SD) cigarettes a day were randomly allocated to receive zimelidine (200 mg/day orally) or placebo in a double-blind crossover study. Another 17 male heavy drinkers smoking 21.1 +/- 14.3 (mean +/- SD) cigarettes a day were randomly allocated to receive citalopram (20 or 40 mg/day orally) or placebo in a double-blind crossover study. In both studies, subjects were not trying to modify their smoking or drinking and received no advice or other treatment to do so. Zimelidine had no effects on the number of cigarettes smoked (F1,4 = 1.80, not significant (NS]. Neither citalopram dose had an effect on smoking (citalopram 20 mg: F1,8 = 0.06, NS; citalopram 40 mg: F1,7 = 0.68, NS). Because intrasubject variation is small, this trial was of sufficient size to exclude with 99.99% confidence the possibility that these drugs decrease smoking behavior by 50%. Since serotonin uptake inhibitors can attenuate ethanol intake in humans, these drugs may have differential effects on consummatory behaviors.