The effects of the benzodiazepine antagonist Ro 15-1788 on psychophysiological performance and subjective measures in normal subjects.

Ro 15-1788 is an imidazodiazepine which was initially described as a pure benzodiazepine antagonist lacking in intrinsic actions. Although recent animal work has shown the drug to have differing intrinsic actions depending on the dose, the majority of studies on human subjects conclude that it is a pure antagonist of benzodiazepines. Two oral doses of Ro 15-1788 (30 mg and 100 mg) were compared with 5 mg diazepam and placebo in their intrinsic effects on a range of psychophysiological, performance and subjective measures in 12 healthy adult subjects. At both these doses Ro 15-1788 showed a mixture of agonist (benzodiazepine-like) effects and other non-benzodiazepine-like effects on the variables measured. Although there was no clear-cut dose-response relationship, the results suggested a predominance of benzodiazepine-like effects at the higher dose on physiological measures whilst the lower dose was observed to have greater effects on a number of behavioural and subjective dimensions. The subjective changes were the opposite of those normally found for benzodiazepines.