Gabazine, a γ-aminobutyric acid type A (GABA<sub>A</sub>) receptor antagonist, has previously been reported to inhibit the binding of [<sup>3</sup>H]NCS-382, a representative ligand of the high-affinity binding site for the neuroactive substance γ-hydroxybutyric acid (GHB). We herein report a study on the structural determinants of gabazine for binding to (i) the orthosteric binding site of the GABA<sub>A</sub> receptor and (ii) the high-affinity GHB binding site. Expanding the structural diversity of available ligands for the high-affinity GHB binding sites, this study identified 2-(imidazo[1,2- b]pyridazin-2-yl)acetic acid as a novel ligand-scaffold leading to analogues with relatively high affinity ( K<sub>i</sub> 0.19-2.19 μM) and >50 times selectivity for the [<sup>3</sup>H]NCS-382 over [<sup>3</sup>H]muscimol binding sites. These results highlight that gabazine interacts with the high-affinity GHB and orthosteric GABA<sub>A</sub> receptor binding sites differently and that distinct analogues can be generated to select between them. To facilitate further in vivo studies, a promising prodrug candidate for brain delivery was identified.