Cetirizine pharmacokinetics and molecular data

List of indications
Absorption Distribution Metabolism Elimination

Absorption
The bioavailability of cetirizine hydrochloride from ZYRTEC-D 12 HOUR Extended Release Tablets is not significantly different from that achieved with separate administration of a cetirizine 5 mg tablet.Return to top

Food interaction
Food had no significant effect on the extent of cetirizine absorption (AUC), but Tmax was delayed by 1.8 hours and Cmax was decreased by 30%.Return to top

Distribution
The mean plasma protein binding of cetirizine is 93%, independent of concentration in the range of 25-1000 ng/mL, which includes the therapeutic plasma levels observed. No plasma protein binding data in humans are available.Return to top

Metabolism
Cetirizine is metabolized to a limited extent by oxidative O-dealkylation to a metabolite with negligible antihistaminic activity. The enzyme or enzymes responsible for this metabolism have not been identified.Return to top

Elimination
After administration of the ZYRTEC-D 12 HOUR Extended Release Tablet, the mean elimination half-life of cetirizine was 7.9 hours.Return to top