ELB-139 (LS-191,811) is an anxiolytic drug with a novel chemical structure, which is used in scientific research. It has similar effects to benzodiazepine drugs, but is structurally distinct and so is classed as a nonbenzodiazepine anxiolytic.
ELB-139 is a subtype-selective partial agonist at GABAA receptors, with highest affinity for the α3 subtype, but highest efficacy at α1 and α2. It has primarily anxiolytic and anticonvulsant effects, but produces little sedative effects or ataxia, and has also been demonstrated in rats to increase serotonin levels in the striatum and prefrontal cortex, without affecting dopamine levels. It has been proposed as a possible candidate for a novel non-sedating anxiolytic or anticonvulsant drug for use in humans, but no trials beyond laboratory work in animals have been conducted to date.