SLEEPINESS AND PERFORMANCE DURING 3-DAY ADMINISTRATION OF CETIRIZINE OR DIPHENHYDRAMINE

Objective: The sedative effects of cetirizine (10 mg once daily), diph enhydramine (50 mg three times daily), and placebo each administered d uring a 3-day period, were compared with objective measures of sleepin ess and performance. Methods: Twelve atopic subjects received each of the three treatments for 3 consecutive days in a double-blind Latin sq uare design. Subjects received either cetirizine at 8:00 AM and placeb o at 3:00 PM and 10:00 PM; diphenhydramine at 8:00 AM, 3:00 PM, and 10 :00 PM; or placebo at all three times. Sleepiness was measured on days 1 and 3 with the multiple sleep latency test at 9:00 AM, 11:00 AM, 1: 00 pns 3:00 PM and 5:00 PM. performance was assessed with a 60-minute simulated assembly line task at 9:30 AM, 11:30 AM, 1:30 PM, and 3:30 P M. Nightly sleep duration was estimated with actigraphy. Results: Comp ared with placebo and cetirizine diphenhydramine produced marked impai rment only on the first day of drug administration, The multiple sleep latency test and the simulated assembly line task values remained sta ble across days with cetirizine and placebo but improved with diphenhy dramine, resulting in no differences among the three conditions on the third day. Conclusion: Unlike cetirizine, diphenhydramine produced ac ute impairment of alertness and performance. By the third day of admin istration, however this impairment was no longer present, apparently b ecause of development of tolerance to the sedative effects.