The effects of fexofenadine at steady-state on sleep architecture: a study using polysomnography in healthy Korean volunteers.

Objectives: To compare the effects of a first-generation antihistamine, chlorpheniramine, with those of the second-generation antihistamine, fexofenadine, at steady-state, on nocturnal sleep architecture in healthy Korean volunteers using polysomnography and the Multiple Sleep Latency Test. We evaluated whether a genetic polymorphism of multi-drug resistance 1 gene (MDR1) could produce variations in pharmacokinetic and pharmacodynamic parameters of fexofenadine. Design/methods: Ten healthy male volunteers received one capsule of fexofenadine 180 mg once each morning or chlorpheniramine 6 mg (2 mg in the morning and 4 mg after 12 h) for 3 days, in a single-site, randomized, double-blind, two-treatment, multiple-dosing, two-way crossover study, with a washout period of 7 days. Overnight polysomnography was measured on the second night of the treatment period. The Multiple Sleep Latency Test was carried out the next morning. Blood samples were taken for the assessment of fexofenadine pharmacokinetics and MDR1 genotyping on the third day. Results: Compared with baseline and fexofenadine, chlorpheniramine significantly increased the latency in rapid eye movement (REM) sleep, with no significant decrease in the percentage of REM sleep. No significant change in latency for REM sleep or percentage REM sleep after dosing with fexofenadine was observed. There was no significant change in the daytime sleepiness with fexofenadine and chlorpheniramine. The effects of MDR1 genotypes and haplotypes on the pharmacokinetics and pharmacodynamics of fexofenadine were not significant. Conclusions: Our findings suggest that fexofenadine and chlorpheniramine at steady-state have no significant effect on nocturnal sleep variables and daytime sleepiness, when compared to baseline.