Evaluation of the sedative properties of PK 8165 (pipequaline), a benzodiazepine partial agonist, in normal subjects

The sedative properties of two doses (50 and 150 mg) of a benzodiazepine partial agonist, PK 8165 (pipequaline), were compared to diazepam 10 mg and placebo in 12 normal volunteers. The assessment, performed before drug intake and 2 and 5 hours after drug intake, included a battery of visual analogue scales and standardized computerized tests (labyrinths, series of digits, colour test, and Zazzo test). Results showed that, at low dose, PK 8165 is not only devoid of any sedative effect but presents psychostimulating properties. In contrast, diazepam 2 hours after intake and PK 8165 150 mg, 5 hours after drug intake induced a significant decrease in performance compared to placebo. This study suggests that small doses of PK 8165 merits further development as an anxiolytic/psychostimulating drug devoid of sedative properties.