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Tenn et al. Allergy Asthma Clin Immunol (2018) 14:5 Allergy, Asthma & Clinical Immunology https://doi.org/10.1186/s13223-017-0227-4 RESEARCH Open Access Onset of action for loratadine tablets for the symptomatic control of seasonal allergic rhinitis in adults challenged with ragweed pollen in the Environmental Exposure Unit: a post hoc analysis of total symptom score Mark W. Tenn1,2,3, Lisa M. Steacy2, Charlene C. Ng4 and Anne K. Ellis1,2,3* Abstract Background: Loratadine is a second-generation, non-sedating antihistamine used for the relief of allergic rhinitis symptoms. Previous studies reported that when loratadine was encapsulated, the onset of action for symptom relief was 180 min. However, unmodifed loratadine tablets were not evaluated at that time. Using data from a previously published Environmental Exposure Unit (EEU) study comparing azelastine nasal spray with loratadine tablets, ceti- rizine tablets, and placebo, this post hoc analysis determines the onset of action of loratadine tablets (i.e. unmodifed) by analyzing the total symptom score for the relief of nasal and ocular seasonal allergic rhinitis (SAR) symptoms. Methods: A Phase IV, randomized, single-center, double-blind, placebo-controlled, double-dummy, four-way crossover study was conducted in the EEU. Seventy participants were randomized sequentially into one of the four treatments during ragweed pollen exposure. Nasal and ocular symptom scores were self-reported by the participants and recorded. The original study analysis was carried out by evaluating the nasal symptom scores only. For this post hoc analysis, both nasal and ocular data from the loratadine and placebo treatment arms were analyzed. The primary endpoint for this analysis was the onset of action of loratadine as measured by the change in total symptom score (TSS) from baseline in comparison to placebo. The onset of ocular symptom relief using the total ocular symptom score (TOSS) was also reported. Results: Loratadine tablets demonstrated a signifcant and durable improvement in both TSS (P .005) and TOSS (P .013) at 75 min post-treatment administration compared to placebo. The mean proportion of= participants report- ing= none or mild for all component symptoms of TSS and TOSS at 75 min and thereafter was signifcantly higher in the loratadine (TSS, P .0005; TOSS, P .0001) vs. placebo treatment arm. = ≤ Conclusions: The onset of action of loratadine tablets was 75 min for the relief of nasal and ocular symptoms in adults with SAR. These results suggest a faster onset of action for loratadine tablets (75 min) compared to previously reported studies which were conducted with modifed (i.e. gelatin-encapsulated) loratadine tablets (180 min). Trial registration Clinicaltrials.gov identifer NCT00561717 Keywords: Allergic rhinitis, Environmental Exposure Unit, Loratadine, Onset of action, Ragweed pollen, Seasonal allergies, Outdoor allergy *Correspondence: [email protected] 3 Division of Allergy & Immunology, Department of Medicine, Queen’s University, Kingston, ON K7L 2V7, Canada Full list of author information is available at the end of the article © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Tenn et al. Allergy Asthma Clin Immunol (2018) 14:5 Page 2 of 7 Background encapsulated form to the currently available marketed, Allergic rhinitis (AR) is an infammatory upper respira- non-encapsulated tablet form. Te aim of the current tory disorder involving IgE-mediated infammation of study was to conduct a post hoc statistical analysis using the nasal mucosa that afects approximately 10–30% of data from the Ellis et al. [10] study to determine the onset the world population [1–3]. Individuals with seasonal of action of unmodifed loratadine tablets in the EEU. allergic rhinitis (SAR) can be reactive to several types of pollen allergens (such as those from ragweed, grass, and Methods tree pollens), experience symptoms such as sneezing, Study design and treatment nasal congestion, nasal and nasopharyngeal itching, and Te clinical methodology of the trial has been published have ocular symptoms like red/itchy and watery eyes [4]. elsewhere [10]. In brief, the trial was a Phase IV, rand- Oral antihistamines are the frst line treatment for SAR, omized, single-center, double-blind, placebo-controlled, of which second generation agents are preferred due to double-dummy, four-way crossover study (clinicaltrials. fewer sedative efects, and a lack of impairment of cogni- gov identifer NCT00561717). Te study was reviewed tive function compared to frst generation compounds [5, and granted ethical clearance by the Queen’s Univer- 6]. sity Health Sciences and Afliated Teaching Hospital Loratadine is a second generation oral histamine Research Ethics Board. It was conducted in accordance H1-receptor antagonist [7]. Previous studies have dem- with the Declaration of Helsinki (Somerset West Amend- onstrated its efcacy for the relief of SAR symptoms over ment 1996) and the International Council for Harmoni- placebo [8, 9]. However, the onset of action for loratadine sation Guideline on Good Clinical Practice. has been variably reported, ranging from 75 to 180 min Te study was conducted in the EEU and was comprised [10–15]. of a screening visit, a priming period, and four dosing/ As defned per the US FDA draft guidance for the exposure periods with a 13-day washout between periods clinical development programs of AR drug products, the (Fig. 1). After eligibility was determined, qualifying partici- onset of action is the frst time point after start of treat- pants were randomized to a treatment sequence comprised ment when the product demonstrates a statistically sig- of one dose of each of the four study medications—aze- nifcant change from baseline in the primary efcacy lastine nasal spray, loratadine tablet, cetirizine tablet, and endpoint that is greater than placebo and is durable placebo. All study treatments were administered as a com- throughout the dosing period [16]. Since 2000, the FDA bination of an oral tablet (active or placebo) and nasal spray recognized the Environmental Exposure Unit (EEU) as (active or placebo) to maintain study blinding. one of three methods to evaluate the onset of action of Each dosing period consisted of an 8-h ragweed pollen products for AR treatment [16]. In comparison to natural challenge in the EEU (mean pollen levels of 3500 ± 500 allergen exposure studies, controlled allergen challenge grains/m3). Te level of pollen used is consistent with facilities such as the EEU are internationally recognized other EEU studies used to determine the onset of allergy and clinically validated models of AR that can be used to products and provides consistent symptomatic responses evaluate products intended for AR treatment [17]. Te in a predictable time frame at a relevant pollen expo- EEU allows for the simultaneous exposure of a controlled sure level [12, 13]. Participants were administered their quantity of allergen to large groups of study participants. assigned treatment 2 h into the challenge. Nasal and ocu- Confounding environmental variables such as humidity, lar symptom severity was recorded by each participant at air quality, CO 2 levels, and temperature can be tightly designated time points during the challenge. Symptom controlled, creating an environment suitable for the eval- severity was rated on a scale of 0–3 (0, none; 1, mild; 2, uation of novel anti-allergic medication [17–19]. moderate; 3, severe) (Table 1). Appropriate combinations A previously reported EEU study evaluated the onset of symptoms comprised the total nasal symptom score of a topically applied intranasal antihistamine spray for (TNSS), total ocular symptom score (TOSS), and total the improvement of SAR symptoms, and loratadine was symptom score (TSS, an omnibus score comprised of all included as one of the comparator treatments [10]. In nasal and ocular symptoms) (Table 2). that study, an onset of action of 75 min for loratadine was reported based on the evaluation of nasal symptoms Study participants alone [10]. Two prior EEU studies conducted by Day Otherwise healthy male and female volunteers aged et al. [12, 13] suggested a longer onset of approximately 18–65 years were included if they had a confrmed his- 180 min for loratadine. However, the authors evaluated tory of ragweed-induced SAR for the preceding two the onset of action of a commercially available loratadine consecutive pollen seasons. A positive skin prick test tablet they had modifed by encapsulating with gelatin. response (defned as a wheal diameter ≥ 3 mm over dilu- Te authors did not demonstrate bioequivalence of the ent control) to ragweed pollen at screening or within Tenn et al. Allergy Asthma Clin Immunol (2018) 14:5 Page 3 of 7 Placebo Cerizine Loratadine Azelasne Cerizine Placebo Azelasne Loratadine Screening Priming Loratadine Azelasne Placebo Cerizine Azelasne Loratadine Cerizine Placebo Randomizaon to 13-day washout periods treatment sequence Fig. 1 Study diagram Table 1 Rating scale for