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ABSTRACT To evaluate the acute effects of two histamine H(1)-receptor antagonists on nocturnal sleep architecture and on next day cognitive function and psychomotor performance.
This was a single-site, randomized, double-blind, 3-way crossover study, comparing the effects of a single dose of chlorpheniramine (6 mg), fexofenadine (120 mg) and placebo in 18 healthy (male and female) Japanese volunteers aged 20-55 years. Volunteers were resident for 3 days and each period was separated by a minimum 5-day washout period. The three treatments were administered at 23.00 h. Overnight sleep was measured from 23.00 h to 07.00 h using polysomnography. Residual effects were studied at 07.00 h and 9.00 h the next morning, with the latency to sleep (sleep latency test) measured at 09.30 h.
Compared with placebo, chlorpheniramine increased the latencies to sleep onset and rapid eye movement (REM) sleep (p < or = 0.05 for both), and reduced the duration of REM sleep (p <or= 0.01), but this was not observed with fexofenadine. As far as residual effects the next morning were concerned there were decrements in performance with chlorpheniramine, but not with fexofenadine. Chlorpheniramine 6 mg impaired divided attention (p < 0.001), vigilance (p < 0.05), working memory (p < 0.0001) and sensori-motor performance (p < 0.01), and the latency to daytime sleep was reduced (p < 0.0001). Six adverse events possibly related to study medication were reported during the study, three of which were related to placebo, two to fexofenadine and one to chlorpheniramine.
These findings suggest that a single nocturnal dose of fexofenadine has advantages over the first-generation antihistamine chlorpheniramine, being free of disruption of night-time sleep and detrimental effects on cognitive performance the next day. It is likely that this advantage will remain with chronic ingestion, but this would need to be confirmed.