A series of pyrido [1, 2-a] benzimidazoles (PBIs) with substitution on the N5-nitrogen has been synthesized and found to possess high affinity for the benzodiazepine (BZD) site on the GABA-A receptor. The compounds evaluated include those bearing a heteroalkyl group and heterocyclic rings. The most promising of these compounds is ethoxymethyl analogue 24, which has an IC50 of 0.1 nM for the BZD site on the GABA-A receptor and has been ...