Administration of theophylline at recommended doses may produce a small (<20%) decrease in the clearance of cetirizine. There is a possible risk for increased cetirizine serum concentrations with large doses of theophylline. Ritonavir increases serum concentrations of cetirizine by approximately 40%, slowing clearance and increasing the elimination half-life. Although not studied, the effect of these drugs on levocetirizine may be similar.[3–5]
Pediatr Pharm. 2010;16(6) © 2010
Cite this: Cetirizine and Levocetirizine Use in Children - Medscape - Jun 01, 2010.