The invention relates to N-[2-hydroxy-3-(1-piperidinyl)-propoxy]-pyridine-1-oxide-3-carboxamidine and its optically active enantiomers. (R)-(-)-N-[2-hydroxy-3-(1-piperidinyl)-propoxy]-pyridine-1-oxide-3-carbox- amidine and (S)-(+)-N-[2-hydroxy-3-(1-piperidinyl)-propoxy]-pyridine-1-oxide-3-carbox- amidine. Furthermore, the invention relates to the preparation of N-[2-hydroxy-3-(1-piperidinyl)-propoxy]-pyridine-1-oxide-3-carboxyimidoyl chloride, which may be used as an active ingredient of medicaments, and the preparation of the optically active enantiomers of this compound using the compounds of the invention as intermediate substances.