Clinical pharmacology of serotonin-altering medications for decreasing alcohol consumption

Abstract

Variations in serotonin neurotransmission influence alcohol consumption (AC). Levels of 5-HT and metabolites are low in some brain regions of alcohol preferring rats and in CSF of alcoholics. Pharmacological treatments which enhance serotonergic neurotransmission (uptake inhibitors, releasers, agonists) consistently reduce AC in rats. Serotonin uptake inhibitors (SUI; e.g., citalopram, fluoxetine) have been studied extensively in humans. In several double-blind randomized, placebo-controlled clinical trials, SUI have consistently decreased AC by averages of 15% to 20% in nondepressed mildly/moderately dependent alcoholics who received no other treatment. Effects were dose-dependent and not related to side effects (few and mild) or changes in anxiety or depression (not observed). SUI also decreased desire to drink and liking for alcohol, thus suggesting a mechanism for effects. Other drugs acting on the 5-HT system have been tested in humans, but results are difficult to interpret. For example, buspirone, a 5-HT1A receptor partial agonist, reduced anxiety and alcohol craving, but not AC; a 5-HT partial agonist, m-CPP, increased alcohol craving in abstinent alcoholics; modest reductions in AC were observed with a 5-HT3 antagonist, ondansetron (0.5 mg/day, but not 4 mg/day). The therapeutic potentials of these medications are being studied. For example, SUI effects on AC were enhanced by a brief psychosocial intervention. Since SUI decrease urge to drink, they may be suitable pharmacological adjuncts in relapse prevention strategies. SUI and other serotonin-altering medications are promising new neuropharmacological treatments for reducing AC.