title: Lack of Clinically Relevant Interaction of Cetirizine on Theophylline Disposition in Healthy Subjects: A Placebo-Controlled Study.
abstract: The possible interaction of a steady-state cetirizine treatment, a nonsedating H(1) antihistamine, on the disposition of a single I.V. infusion of theophylline was studied in six healthy male volunteers. As a corollary, it was checked whether this single theophylline administration modified the steady-state condition of cetirizine. A three-period, two-treatment, crossover design was used, each period being separated by a washout of 1 week. Each period consisted of the oral administration of 10 mg cetirizine or of a matching placebo every 12 h for 3½ days, the last intake being followed, 1 hour later, by a single 1-h I.V. infusion of 240 mg theophylline or of placebo. The sequence of treatments (A = cetirizine + theophylline placebo, B = cetirizine placebo + theophylline, C = cetirizine + theophylline) was alloted by a double Latin-square randomization. The repeated administration of cetirizine induced a 3% decrease of the urinary elimination of unchanged theophylline; the total body clearance of theophylline was marginally (+5%) and not significantly modified. Theophylline slightly lengthened the elimination half-life of cetirizine (from 8.3 to 9.9 h), without modification of its apparent total body clearance; the half-life of cetirizine remaining in the normal range. These subtle modifications are not clinically relevant and it may, thus, be considered that cetirizine exerts no pertinent interaction on theophylline disposition.
authors.affiliation: Laboratoire de Pharmacothérapie, Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: R.
authors.initials: R
authors.lastname: Hulhoven
authors.forename: J. P.
authors.initials: JP
authors.lastname: Desager
authors.forename: C.
authors.initials: C
authors.lastname: Harvengt