Modulation of ethanol intake by serotonin uptake inhibitors

The most commonly prescribed agents for decreasing ethanol intake are alcohol-sensitizing drugs; however, their efficacy is unproven, they are associated with toxicity, and there are several contraindications for use. A program to identify and test new drugs to decrease ethanol intake has focused on drugs that enhance central serotonergic neurotransmission and consistently attenuate ethanol consumption. Animal studies have shown consistent findings with direct and indirect serotonin (5-HT) agonists. Ethanol intake decreased after the administration of 5-HT precursors, 5-HT uptake inhibitors, intracerebral 5-HT, and postsynaptic 5-HT agonists; in contrast, destruction of serotonin-containing neurons with 5,6- or 5,7-dihydroxytryptamine increased ethanol intake. Administration of zimelidine (200 mg/day p.o.) to 16 healthy alcohol abusers was associated with a significant increase in number of abstinent days and a decrease in number of drinks consumed. Approximately 50% of the subjects were responders, 35% were partial responders, and 10%-15% were nonresponders. In a recent double-blind crossover study, citalopram, an even more selective serotonin uptake inhibitor, produced similar results. Because serotonin uptake inhibitors acted rapidly and subjects were not clinically depressed, this action is distinct from antidepressant effects. These drugs most likely interfere with the neurobiologic mechanisms regulating ethanol intake and provide an innovative approach for modulating the use of alcohol in problem drinkers.