Direct measurement of daytime sleepiness after administration of cetirizine and hydroxyzine with a standardized electroencephalographic assessment.

Alertness is a vital function, and medications that do not impair this vital function are clinically desirable in terms of safety. In a comparative study to measure daytime alertness objectively, 60 men and women in good health were assigned to receive either cetirizine, 5 mg, 10 mg, or 20 mg, hydroxyzine, 25 mg, or placebo in a randomized, double-blind, parallel-group design. Subjects slept in the laboratory for 2 consecutive nights to facilitate adaptation. During the second night, the subjects' sleep patterns were recorded by electroencephalogram (EEG), electrooculogram, and chin electromyogram. After the second night, subjects were awakened at 7:30 AM and given a single dose of the assigned treatment. Multiple Sleep Latency Tests (standardized 20-minute opportunities to fall asleep in bed while EEG and eye movements are recorded) were given every 2 hours. Subjects who received cetirizine did not differ from control subjects given placebo in any measure of daytime alertness. Subjects who received hydroxyzine were significantly more sedated than were control subjects given placebo for about 4 hours after treatment. The data from this study provide evidence that cetirizine does not differ from placebo with respect to alertness. The usefulness of the specific and sensitive standardized electroencephalogram, compared with alternative assessments of daytime alertness, is discussed.