Piperidines derivatives and their use as serotonin receptor antagonists

Pharmaceutical researchers have discovered that the neurons of the brain which contain monoamines are of extreme importance in a great many physiological processes which affect many psychological and personality-affecting processes as well. In particular, serotonin (5-hydroxytryptamine; 5-HT) has been found to be a key to a very large number of processes which affect both physiological and psychological functions. Drugs which influence the function of serotonin in the brain are accordingly of great importance and are now used for a large number of different therapies. The present invention provides compounds of formula (I): which are useful for treating depression, anxiety, and alleviating the symptoms caused by withdrawal or partial withdrawal from the use of tobacco or of nicotine.