Use of a compound of formula (A), wherein: ##STR00001## W is a residue which imparts antagonistic and/or agonistic activity at histamine H.sub.3-receptors when attached to an imidazole ring in 4(5) position; R.sup.1 and R.sup.2 may be identical or different and represent each independently a lower alkyl or cycloalkyl, or taken together with the nitrogen atom to which they are attached, a saturated nitrogen-containing ring (i) as defined, a non-aromatic unsaturated nitrogen-containing ring (ii) as defined, a morpholino group, or a N-substituted piperazino group as defined for preparing medicaments acting as antagonists and/or agonists at the H.sub.3-receptors of histamine.