Abstract

Onset of action is recognized as an important pharmacologic property of allergic rhinitis (AR) medications. This study was designed to evaluate the onset of action of loratadine/montelukast (L/M; 10 mg/10 mg) versus placebo in subjects with ragweed-induced seasonal AR (SAR). A single-center, double-blind, parallel-group study of ragweed-sensitive AR subjects (n = 310) was performed in the Environmental Exposure Unit (EEU). Subjects were exposed to ragweed pollen in the EEU and symptoms were recorded at 30, 60, 90, and 120 minutes before a single dose of L/M or placebo. After dosing, symptoms were recorded for 4 hours, at 15-minute intervals for the first 2 hours and at 30-minute intervals for the final 2 hours. The primary end point was time to onset of action of L/M, defined as the first time point at which the mean change from baseline in total symptom score (TSS) for L/M became and remained significantly better than placebo. Secondary end points included nasal congestion scores and peak nasal inspiratory flow (PNIF). The onset of action of L/M for TSS was 1 hour and 15 minutes (p = 0.005 versus placebo). L/M reduced nasal congestion as indicated by significant improvements in both the nasal congestion score (p = 0.011) and the PNIF measurements (p = 0.007) within 1 hour and 15 minutes postdose. The incidence of treatment-emergent adverse events was similar between groups. The onset of action after treatment with L/M was 1 hour and 15 minutes for TSS, as well as nasal congestion. L/M was well tolerated.