Compounds of formula (I) 1 wherein R.sub.1 or R.sub.2 is an aromatic or non-aromatic ring directly joined or joined by a linker, as represented by L.sub.2 and L.sub.3, to a heteroaromatic core, and X, X', Y, Y', Z, Z', R.sub.1, R.sub.2, R.sub.3, R.sub.3a, R.sub.3b, R.sub.4, R.sub.5, L, L.sub.2, and L.sub.3 are as defined herein, are useful in treating conditions or disorders prevented by or ameliorated by histamine-3 receptor ligands. Also disclosed are pharmaceutical compositions comprising the histamine-3 receptor ligands, methods for using such compounds and compositions, and a process for preparing compounds within the scope of formula (I).