The amnesic action of diazepam, flunitrazepam and lorazepam in man.

Studies in man show that it is possible to reliably study the incidence, degree and duration of amnesia produced by drugs by showing patients 10 postcards and testing their ability to recall or recognise them six hours later. Using this method of study it was found that 1 mg flunitrazepam produced a comparable degree of amnesia to 10 mg diazepam, although its action was slightly longer. This difference was more marked when double doses were studied. The onset of the amnesic action of both drugs occurred within 2 minutes of their intravenous injection and rarely persisted for more than 10-15 minutes. In contrast, with 4 mg lorazepam the onset of amnesia was slower and persisted for up to 270 minutes. This was accompanied by a moderate but not excessive amount of drowsiness. Possible clinical uses for such a drug deserve serious consideration.