Further observations on the effects of subhypnotic doses of midazolam in normal volunteers.

Abstract

Our studies on the effects of subhypnotic doses of midazolam in healthy adult volunteers have been extended with special emphasis on clinical electrophysiological endpoints of sedation and attention coupled with various tests of memory. We measured the many components of the P300 event-related brain potential to infrequent (rare) tones. Midazolam HCl was given in a dose of .02 mg/kg i.v. three times at approximately 15-minute intervals after obtaining baseline electrophysiological recordings and memory test results. Marked individual variation was observed with these small doses of midazolam. Some subjects were markedly sedated, whereas others showed relatively little sedation. Electroencephalogram (EEG) beta activity increased while alpha activity decreased following midazolam. Even though the subjects given midazolam were awake, there was a striking attention deficit that correlated well with the accuracy of counting rare tones and the alterations in various components of the late auditory event-related brain potential.