Irsenontrine (E2027) maleate is a selective and orally active inhibitor of phosphodiesterase 9 (PDE9). It can be utilized in the study of neurological diseases.

Irsenontrine (0.3, 3.3 mg/kg; p.o.) maleate exhibits a significant ameliorative effect on the percentage of exploration of the novel object at 3.3 mg/kg in Scopolamine-induced rats[1]. Irsenontrine (1 mg/kg; p.o.) maleate and memantine hydrochloride (1 mg/kg; p.o.) combined treatment group exhibits a significantly higher percentage of exploration of the novel object than memantine hydrochloride (1 mg/kg) alone[1].