Effect of midazolam on memory.

The effect of a single bedtime dose (7.5 or 15 mg) of 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazol[1,5-a] [1,4]benzodiazepine (midazolam, Ro 21-3981, Dormicum) on memory was investigated in young, healthy adults. 2 h after drug intake the subjects were awakened and presented with a series of tasks. Recall was assessed immediately following the task presentation and after awakening in the morning. Immediate recall at night was impaired by the 15 mg dose. A further, dose-dependent decrement of recall from night to morning was observed. In contrast to the immediate deficit, the delayed amnestic effect showed little interindividual variability, was largely independent of the type of task, and was significant even for the 7.5 mg dose. Recall of a list of words learnt before drug intake was not impaired by the lower dose, and was enhanced by the higher dose. The results indicate that two separate processes underlie the immediate and the delayed anterograde amnestic action of benzodiazepines.