Brain histamine H1 receptor occupancy of newly-marketed non-sedating antihistamines: PET measurement in normal volunteers - Histamine H1 receptor occupancy of antihistamines

There was no significant difference between the mean brain histamine H1 receptor occupancy (H1RO) after levocetirizine administration and fexofenadine administration. Similarly, subjective sleepiness was not significantly different between the two antihistamines and placebo. Neither subjective sleepiness nor plasma concentrations was significantly correlated with the brain H1RO of the two antihistamines. At therapeutic dose, levocetirizine does not bind significantly to the brain H1Rs and does not induce significant sedation.