A simulated car-driving study on the effects of acute administration of levocetirizine, fexofenadine, and diphenhydramine in healthy Japanese volunteers.

OBJECTIVE: Antihistamines are often used for treating allergic rhinitis. However, many older antihistamines cause sedative side effects. The sedative effects of antihistamines on car-driving have been investigated. This has not been investigated for levocetirizine, a new-generation antihistamine, in Asian populations, and so we evaluated its sedative effects in healthy Japanese subjects. METHODS: In this double-blind, placebo-controlled, four-way crossover study, healthy volunteers received single doses of levocetirizine 5 mg, fexofenadine 60 mg, diphenhydramine 50 mg, and placebo at intervals of at least 6 days. Simple brake reaction time and choice brake reaction time task (CBRT), a lateral tracking (LT) task, and a multiple task, a mixture of CBRT and LT task, were used to compare driving performance between the four drugs. Subjective sedation was also assessed. RESULTS: The simple brake reaction time and CBRT, and the CBRT component of the multiple task, did not show any significant differences between the drugs. In contrast, the LT, both as a single parameter and as a component of the multiple task, showed significant differences between diphenhydramine and the newer-generation antihistamines in a manner that corresponds with subjective sedation. CONCLUSIONS: Levocetirizine and fexofenadine did not impair psychomotor performance in subjects performing simulated car-driving tasks, while diphenhydramine did impair psychomotor performance in the subjects. Copyright © 2016 John Wiley & Sons, Ltd.

Dual-task interference in simulated car driving: The psychological refractory period effect when not only the second, but also the first task is ecologically relevant.

The psychological refractory period (PRP) effect denotes the finding that shortening the temporal interval between two tasks leads to increased reaction time in the second task. Earlier work in driving simulators confirmed the emergence of a PRP effect even if the second task (T2) was ecologically relevant, such as in a car-braking task. Here we evaluate the PRP effect if the first task (T1) is ecologically relevant as well. In a driving simulator, participants had to warn pedestrians against crossing the street (T1), and had to brake when the lead car braked (T2). As the temporal interval between tasks decreased, reaction time in T2 increased, confirming once more the emergence of a PRP effect. The PRP effect in our study was larger than in previous studies where T1 was artificial rather than ecologically relevant. This suggests that an ecologically relevant T1 is processed more elaborately, resulting in stronger interference with T2.