SB 271046 hydrochloride (SB 271046A) is selective, orally active 5-HT6 antagonist (pKi values are 9.02-8.92, 6.35, 6.55, 6.27 at 5-HT6, 5-HT1A, 5-HT1D and D3, and 6.05, 5.95, 5.76, 5.73, 5.62, 5.55, 5.41, 5.39, 5.27 and < 4.99 at 5-HT1B, 5-HT1F, α1B, 5-HT2C, 5-HT2A, D2, 5-HT2B, 5-HT7, 5-HT4 and 5-HT1E respectively) and is > 200-fold selective over 55 other receptors, enzymes and ion channels. It increases extracellular aspartate and glutamate in the frontal cortex and exhibits anticonvulsant activity (EC50: 0.16 μM).