Xyzal Drug Interactions

No interaction studies have been performed with levocetirizine (including CYP3A4 inducers); studies with the racemate compound cetirizine demonstrated that there were no clinically relevant adverse interactions (with pseudoephedrine, cimetidine, ketoconazole, erythromycin, azithromycin, glipizide and diazepam).
Theophylline: A small decrease in the clearance of cetirizine (16%) was observed in a multiple-dose study with theophylline (400 mg once daily) while the disposition of theophylline was not altered by concomitant cetirizine administration.
Ritonavir: In a multiple-dose study of ritonavir (600 mg twice daily) and cetirizine (10 mg daily), the extent of exposure to cetirizine was increased by about 40% while the disposition of ritonavir was slightly altered (-11%) further to concomitant cetirizine administration.
Food: The extent of absorption of levocetirizine is not reduced with food, although the rate of absorption is decreased.
Alcohol: In sensitive patients, the simultaneous administration of cetirizine or levocetirizine and alcohol or other CNS depressants may have effects on the CNS, although it has been shown that the racemate cetirizine does not potentiate the effect of alcohol.