Characterization Of Allergic Rhinitis Symptomotology Induced By a Nasal Allergen Challenge (NAC) Titration In a Dust Mite Sensitize Population

Allergic rhinitis signs and symptoms can be safely and precisely evaluated using nasal allergen challenge (NAC) titration. Eligible skin test positive dust mite subjects underwent NAC titration. Challenge titration began with bilateral instillation of 100uL of saline. Increasingly concentrated doses of dust mite allergen were instilled until a positive reaction was elicited. Primary endpoint was Total Nasal Symptom Score (TNSS, 0 to 12 scale) the sum of nasal itching, congestion, rhinorrhea, and sneezing (0 to 3 scales). A positive NAC was defined as TNSS > 8 within 15 minutes of instillation. Secondary measures included investigator evaluated inflammation (0 to 4 scale). Twenty-one (21) subjects were screened and 13 successfully completed NAC titration. Baseline TNSS scores were 0.38+0.87 increasing to 9.2+1.2 following the qualifying challenge. Individual post-NAC scores were: itching, 2.0±0.8; congestion, 2.5±0.5; rhinorrhea, 2.4±0.5; and sneezing, 2.1±0.5. The post NAC Nasal Inflammation Score (NIS) was 2.6+1.5. The dose of allergen needed for qualification varied from 2 to 8 concentrations. Twenty-five percent of subjects demonstrated negative correlation between signs and symptoms R= -0.85. NAC titration is a useful tool for characterizing the rhinitis response of a study subject to a particular allergen. Additionally, the NIS may be useful as an enrichment tool for clinical trials.