An investigation into the effects of cetirizine on cognitive function and psychomotor performance in healthy volunteers

Objective: The cognitive and psychomotor effects of 2.5, 5 and 10 mg cetirizine, a second-generation H-1 receptor antagonist, were compared with loratadine 10, 20 and 40 mg, promethazine 25 mg and placebo in 24 healthy Volunteers in a double-blind, randomised cross-over study. Methods. Following each dose, subjects were required to perform a series of tests of cognitive function and psychomotor performance at 1.5, 3 and 6 h post-dose. The test battery consisted of critical flicker fusion (CFF), choice reaction time (CRT), compensatory tracking task (CTT) and assessment of subjective sedation (LARS). Results: Cetirizine and loratadine at all doses tested were not significantly different from placebo in any of the tests used. However, as expected for a verum, all measures with the exception of CTT were significantly disrupted by promethazine (P < 0.05). Promethazine caused a reduction in CFF threshold at all test points; these differences were significant at 3h and 6h post-dose (P < 0.05). There was also a significant increase in total reaction time at 3 h post-promethazine administration. Subjective reports of sedation were significantly greater following the administration of promethazine at all time points (P < 0.05). Conclusions: These results allow the conclusion that cetirizine at its recommended therapeutic dose of 10 mg is demonstrably free from disruptive effects on aspects of psychomotor and cognitive function in a study where the psychometric assessments have been shown to be sensitive to impairment, as evidenced by the effects of the positive control, promethazine 25 mg.