Sibutramine : A new weight loss agent without evidence of the abuse potential associated with amphetamines

Sibutramine is a serotonin and norepinephrine reuptake inhibitor that has shown efficacy as a weight loss and weight maintenance agent. Because of the abuse liability and physical dependence potential of amphetamines and related antiobesity agents, this study evaluated the abuse potential of sibutramine and compared it with that of dextroamphetamine and placebo in recreational stimulant users. Thirty-one male recreational stimulant users participated in this single-site, Latin square crossover study that compared the effects of two doses of sibutramine (20 mg and 30 mg) to dextroamphetamine (20 mg and 30 mg) and placebo, using a series of validated subjective scales or questionnaires. For scales measuring stimulation and euphoria, there was a greater mean response for dextroamphetamine 30 mg versus 20 mg, with both doses having a significantly greater stimulant and euphoric effect than placebo at the majority of time points (p < 0.05); responses for both doses of sibutramine were statistically indistinguishable from placebo at all time points. Responses to "street value" and "most enjoyed study session" questions confirmed that sibutramine lacks abuse potential; mean cash value estimates of street value were significantly greater for both dextroamphetamine doses than for placebo or either sibutramine doses (p < 0.05), and the rank order of session enjoyment placed both doses of sibutramine last. Together with the relatively late Tmax of the active metabolites (3-4 hours), this short-term, single-dose study provides strong evidence that sibutramine does not have the potential for abuse that is characteristic of amphetamines and that it is indistinguishable from placebo in abuse potential.