Abstract
Purpose: :
Allergic rhinoconjunctivitis (ARC) chamber studies to date have consolidated signs and symptoms from different organs (ie, eye, nose, and ear) into a single aggregate score. By doing this, the manner in which specific drugs act on individual signs or symptoms can be lost or diluted. To effectively evaluate and compare different anti-allergic therapies and their effects on individual ARC symptoms, higher symptomatology must be achieved. A novel clinical model, the Allergen BioCube (ABC), was developed to modify the aeroallergen distribution process to more closely mimic the environment for each subject, and enhance overall levels of ARC signs and symptoms. The use of conjunctival allergen challenge (CAC) after ABC exposure was also explored for its ability to enhance ARC signs and symptoms at following visits.
Methods: :
A single-center, IRB-approved study was conducted. 15 subjects with a history of ARC and sensitivity to ragweed (RW) and dust mites (DM) or RW alone were enrolled and exposed to RW (seasonal) in the ABC (2 hrs on 4 consecutive days; visits 2-5). Subjects sensitive to both RW and DM (n=12) were CACed with either DM (pan-seasonal) (n=6) or placebo (n=6) following ABC exposure (visits 2-4). Subjects underwent re-challenge with RW in the ABC the following day. Conjunctival redness and ocular itching were assessed every 15 min during ABC exposure using standardized 0-4 unit scales. Nasal pruritis, rhinorrhea, sneezing, and congestion were assessed at the same interval using standardized 0-3 unit scales, and were combined to generate a total nasal symptom score (TNSS) (range: 0-12).
Results: :
11 subjects (73.3%) had a positive nasal response, with a mean peak TNSS of 7.84; mean peak individual scores were 1.91 (pruritis), 1.93 (sneezing), 2.07 (rhinorrhea), and 2.14 (nasal congestion). Within this population, minimal ocular signs and symptoms were observed. The addition of CAC with DM did not significantly enhance either TNSS or ocular signs and symptoms in the ABC.
Conclusions: :
The ABC successfully produced clinically significant nasal, but not ocular, signs and symptoms in subjects with ARC. The differing responses of the two organs suggest that the underlying physiological mechanisms may be disparate. Furthermore, the enhanced nasal response seen in the ABC suggests it will be a successful model to show the effect of therapeutic agents on individual components of TNSS.
Clinical Trial: :
http://www.clinicaltrials.gov NCT00985296
Keywords: conjunctivitis • clinical (human) or epidemiologic studies: systems/equipment/techniques • cornea: clinical science