A potent GABA uptake inhibitor, selective for GAT-1 (IC50 values are 0.13, 550, 944 and 7210 μM for hGAT-1, rGAT-2, hGAT-3 and hBGT-1 respectively). Inhibits transport current competitively (Ki = 7 μM) and transmitter-gated current non-competitively (Ki = 0.03 nM). Able to pass the blood-brain barrier after systemic administration and is active in vivo.