Ro4938581 is a nootropic drug invented in 2009 by a team working for Hoffmann-La Roche, which acts as a subtype-selective inverse agonist at the ñ<sub>5</sub> subtype of the benzodiazepine binding site on the GABA<sub>A</sub> receptor. It has good selectivity for the ñ<sub>5</sub> subtype and did not produce convulsant or anxiogenic effects in animal studies, making it a promising potential nootropic. Ro4938581 and a related derivative basmisanil (RG-1662, RO5186582) have subsequently been investigated for the alleviation of cognitive dysfunction in Down syndrome.