N-OXIDES OF PYRIDYLMETHYL -PIPERAZINE AND -PIPERIDINE DERIVATIVES

N-oxides of certain pyridylmethylpiperazine and -piperidine derivatives are provided as alternatives to or as "prodrugs" of their respective parent compounds, as well as pharmaceutical compositions containing these N-oxides, methods for preparing them, and compositions comprising them. The N-oxides have the formula (a) wherein the substituents have the meanings given in the description, and wherein the oxidized nitrogen atom can be the nitrogen atom in the pyridyl ring of R5, or the nitrogen atom in the piperidine ring (when Z is carbon) or either one of the nitrogen atoms in the piperazine ring (when Z is nitrogen), or both the nitrogen atom connected to R5 via a methylene group, and the nitrogen atom in the pyridyl ring of R5, and tautomers, stereoisomers, pharmacologically acceptable salts, hydrates, and solvates thereof. In addition, the N-oxides and compositions can be used as medicaments useful in the treatment of affections or diseases of the central nervous system caused by disturbances in either the dopaminergic or serotinergic systems.