A neurosteroid anesthetic that directly activates and potentiates GABAA receptor-activated membrane current (IGABA). Efficacy but not potency is determined by the alpha subunit of the receptor (EC50 values are 1.4, 1.8, 2.1, 2.4 and 2.5 μM for α1β1γ3, α1β1γ1, β1γ1, α2β1γ2L and α1β1γ2L isoforms respectively).