Driving ability after acute and sub-chronic administration of levocetirizine and diphenhydramine: a randomized, double-blind, placebo-controlled trial.

Author(s): Verster JC, de Weert AM, Bijtjes SI, Aarab M, van Oosterwijck AW, Eijken EJ, Verbaten MN, Volkerts ER

Affiliation(s): Utrecht Institute for Pharmaceutical Sciences, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands. J.C.Verster@pharm.uu.nl

Publication date & source: 2003-08, Psychopharmacology (Berl)., 169(1):84-90. Epub 2003 Apr 30.

Publication type: Clinical Trial; Randomized Controlled Trial

RATIONALE: Sedation following antihistamine use poses a danger to ambulant patients involved in daily activities such as driving. OBJECTIVE: To investigate effects of levocetirizine (5 mg), diphenhydramine (50 mg), and placebo on driving ability during normal traffic. METHODS: Forty-eight healthy volunteers participated in a double-blind, placebo-controlled, randomized clinical trial. Treatments were administrated on days 1, 2, 3 and 4, exactly 1.5 h before the start of the standardized driving test (performed on day 1 and day 4). In the standardized driving test, subjects were instructed to drive with a steady lateral position, while maintaining a constant speed (95 km/h). Primary parameter was the standard deviation of lateral position (SDLP; cm). Statistical analyses were performed separately for day 1 and day 4, using analysis of variance and an equivalence test. Equivalence to placebo was evidenced if the 95% confidence interval lay between -2.6 cm and +2.6 cm. RESULTS: SDLP after levocetirizine was equivalent to placebo on both day 1 (-0.66 cm; +1.12 cm) and day 4 (-0.37 cm; +1.28 cm). In contrast, SDLP after diphenhydramine differed significantly from placebo on both day 1 ( P<0.0001) and day 4 ( P<0.0003). On day 1, the 95% confidence interval of diphenhydramine (+1.85 cm; +3.63 cm) was partially above the upper equivalence limit (+2.6 cm), indicating clinically relevant driving impairment. On day 4, however, the 95% confidence interval of diphenhydramine (+0.74 cm; +2.38 cm) was contained within the acceptance range. CONCLUSION: In contrast to diphenhydramine, driving performance was not significantly affected while using 5 mg levocetirizine once daily.