Intranasally administered atropine methonitrate treatment of experimental rhinovirus colds

The role of parasympathetic/cholinergic mechanisms in the syndrome of the common cold is not clear. Under double-blind, randomized, placebo-controlled conditions, we intranasally administered the anticholinergic atropine methonitrate (AM) to assess its tolerance in uninfected adults and therapeutic efficacy in volunteers with experimental rhinovirus (RV) colds. Healthy adults given sprays of AM intranasally 250 or 500 micrograms 4 times a day for 5 days developed nasal dryness and systemic side effects more often than did placebo (P) recipients. In 2 separate challenge studies, treatments were begun with AM 125 micrograms 3 times a day (AM = 8, P = 7) or AM 250 micrograms 4 times a day (AM = 9, P = 7) for 5 days, 24 h after intranasal inoculation of RV type 39. The low AM dose was well tolerated but had no effect on nasal mucus weights or nasal symptom scores in persons with RV colds. The higher dose of AM was associated with subjective drying and a reduction in nasal mucus production. These findings suggest that cholinergic mechanisms have a role in the pathogenesis of RV colds but that more work is necessary to determine if anticholinergic compounds will be of practical value in their treatment.