Z944 is an orally available, state-dependent, potent and selective T-type calcium channel blocker (hCav3.1/Cav3.2/Cav3.3 IC50 by voltage clamp = 50/160/110 nM under ~30% inactivated state & 130/540/260 nM in the closed state) over non-T-type voltage-gated channels (rCaV2.2 IC50 = 11 µM/30% inactivated & 150 µM/closed; hERG/rCaV1.2/hNaV1.5 IC50 = 7.8/32/100 µM). Z944 effectively suppresses seizure activity in the GAERS (absence epilepsy rats from Strasbourg) model in vivo (10-30 mg/kg qod ip.) with no adverse cardiovascular effects or neurotoxicity.