Setin Drug Interactions

No interactions were observed in pharmacokinetic interaction studies when Cetirizine was used concomitantly with pseudoephedrine or antipyrine.
No clinically important interactions have been reported in patients receiving Cetirizine concomitantly with azithromycin, erythromycin, or ketoconazole.
Small decrease in the clearance of Cetirizine was observed in a multiple-dose study when theophylline was administered with Cetirizine; disposition of theophylline was not altered by the concomitant administration with Cetirizine.
In particular, concomitant administration of Cetirizine with macrolides or ketoconazole has never resulted in clinically relevant ECG changes. Concomitantly administration of Cetirizine with drugs known to inhibit cytochrome P450 microsomal enzymes (e.g., azithromycin, erythromycin, ketoconazole) has not been associated with clinically important changes in ECG parameters (e.g., QT_c intervals).
In a multiple dose study of ritonavir and Cetirizine, the extent of exposure to Cetirizine was increased by about 40% while disposition of ritonavir was slightly altered further to concomitant Cetirizine administration.
Concomitant use of Cetirizine with CNS depressants (e.g., alcohol, sedatives, tranquilizers) may result in additive CNS depression.