Reproducibility of nasal function measurements with histamine and adenosine monophosphate nasal challenge testing in patients with allergic rhinitis

Background: Adenosine monophosphate (AMP) acts by releasing inflammatory mediators from mast cells and may be used for bronchial and nasal provocation tests. The aim of the present study was to determine whether AMP could be used in a dose–response manner to evaluate nasal function and to evaluate the reproducibility of nasal function measurements with nasal challenge testing using histamine and AMP in patients with perennial allergic rhinitis. Methods: Nine patients were challenged on three separate occasions for each challenge with doubling doses of either histamine (0.25–8 mg/mL) or AMP (25–800 mg/mL). Challenge measurements were made of peak inspiratory flow rate (PIFR), acoustic rhinometry (AR) and rhinomanometry (Rhino). The provocation concentration (PC30) was calculated in order to produce: (i) a 30% fall in PIFR; (ii) a 30% fall in AR and (iii) a 30% increase in nasal airway resistance in Rhino and a symptom score of 10 (of 40). The mean intrasubject coefficient of variation (CV) was calculated for baseline and the corresponding PC. Results: Baseline CV prior to histamine were 15.1, 19.6 and 15.8 for PIFR, AR and Rhino, respectively; prior to AMP, baseline CV were 12.7, 19.6 and 10.6% for PIFR, AR and Rhino, respectively. For histamine challenge, the PC30 were 26.5, 27.4 and 38.7% for PIFR, AR and Rhino, respectively. For AMP challenge, the PC30 CV values were 46.2, 30.8 and 49.5% for PIFR, AR and Rhino, respectively. There was no significant difference in the provocative dose required to cause a predetermined change in response or the response at 1 mg/mL histamine and 100 mg/mL AMP. Conclusions: Adenosine monophosphate may be used as a challenge agent for nasal challenge testing, although it results in greater variability than histamine.