Introduction The aim of this proof-of-concept study was to assess whether nasal adenosine monophosphate (AMP) challenge may be used to quantify dose response to topical fluticasone propionate (FP) in persistent allergic rhinitis (PER).
Methods Eligible subjects with PER entered a randomized double-blind crossover study of 2 weeks of intranasal FP at 100 μg or 400 μg daily, with a 2-week placebo washout period before each randomized treatment. Measurements after each washout or treatment comprised: peak nasal inspiratory flow (PNIF) response to nasal AMP (the primary outcome), domiciliary PNIF, the mini rhinoconjunctivitis quality of life questionnaire (miniRQLQ), symptom scores, nasal nitric oxide levels and overnight urinary cortisol:creatinine ratios.
Results Thirteen patients completed per protocol. Maximal PNIF response to AMP was attenuated 0.9% (95% confidence interval −7.1 to 9.0, P=NS) by FP 100 μg, and 12.9% (4.8–20.9, P=0.009) by FP 400 μg. The 400–100 μg difference was 12.0% U (2.6–21.3, P=0.049). None of the other outcomes were responsive enough to detect any significant treatment effects. The standardized response means to FP 400 μg were 81% for AMP challenge, 54% for domiciliary PNIF, 53% for miniRQLQ, 24% for symptom scores and 18% for nasal nitric oxide. No adrenal suppression was detected at either dose.
Conclusion FP exhibited dose-related suppression of nasal airway hyperresponsiveness to AMP challenge, but without associated detectable adrenal suppression at the higher dose. Moreover, the AMP response demonstrated the highest signal to noise ratio compared with other outcome measures in PER.