Abstract
The aim of the present trial was to compare the sedative effects of second generation antihistamines in healthy adult male volunteers. This randomized, double-blind, cross-over clinical trial compared the effects of single doses of olopatadine 5 mg, ketotifen fumarate 1.38 mg, fexofenadine 60 mg, and placebo on psychomotor function in 15 healthy male subjects who gave written informed consent for participation in the study. For each sedative, sleep latency time was measured using the multiple sleep latency test (MSLT); and psychomotor function was measured by thresholds of critical flicker fusion (CFF), the digit symbol substitution test (DSST), and a Straight line Analog Rating Scale (LARS). Measurements were performed before and 2, 5, and 8h after drug administration. The differences between the drugs and placebo were analyzed by repeated analysis of variance (ANOVA) and paired t-tests as appropriate. Intergroup differences in baseline values of all parameters were not significant. Ketotifen induced the shortest sleep latency at 2h (p＝0.03 vs. fexofenadine, p=0.03 vs. olopatadine) and 5h (p=0.04 vs. fexofenadine) after administration. Ketotifen also showed the most prolonged recognition (CFF down) at 2h (p<0.001 vs. fexofenadine, p=0.03 vs. olopatadine) and 8h (p=0.01 vs. fexofenadine). Olopatadine showed a more prolonged recognition than fexofenadine at 2h (p=0.03). Ketotifen induced the greatest decline in concentration and cognitive function at 8h (p=0.03) according to DSST. The drugs affected objective psychomotor function without causing subjective symptoms as shown by no significant differences in LARS score. The study indicates that the extent of impaired performance, an important adverse drug reaction, may differ even among second generation antihistamines.
