Effect of ipratropium on nasal reactivity to histamine and eosinophil influx in perennial allergic rhinitis.

In a double-blind, placebo-controlled study nasal saline and histamine provocation tests were performed in patients with perennial allergic rhinitis in order to assess changes in eosinophil influx and non-specific nasal reactivity after 8 days of treatment with ipratropium bromide. A "nasal pool" method was used to trace changes in protein level and eosinophil influx into nasal secretions. Treatment with ipratropium 80 mg q.i.d. caused a significant decrease in the albumin and total protein level in saline washings and induced a five-fold increase in eosinophils as compared to the placebo treatment. The nasal mucosal response to histamine, assessed as the number of sneezes and protein level, was more responsive to ipratropium treatment than the mucosa from placebo-treated subjects. Since eosinophil numbers were correlated with an increase in the vascular and sneezing responses, it appears that ipratropium potentiates inflammatory mechanisms when used in subjects with an allergy in the nasal mucosa.