The development of subsensitivity to nebulized atropine sulfate

Ten adult asthmatic subjects were tested for response to inhaled atropine sulfate before and after 3 weeks of inhaled atropine therapy. Four of the ten initial responders no longer responded after the 3 weeks. The mean FEV1 increase was 0.49 L before treatment and 0.30 L after treatment (P = .025). Subsensitivity to the effects of atropine develops, but may be limited to a subset of patients.