Abstract
In 46 never-smoking randomly chosen patients with non-allergic asthma, 40 to 60 years old, a methacholine hyperreactivity test and lung function tests were performed after inhalation of different doses of ipratropium bromide (IB). The grade of hyperreactivity was measured as the cumulative dose of methacholine necessary to produce a decrease in the forced expiratory volume in one second of 20% of the lowest post-NaCl value (PD20). The following lung function tests were carried out: Lung volumes, ventilatory capacity including flow-volume curves, airway resistance and nitrogen single-breath wash-out test. The bronchodilator effect, measured as a change in the different lung function tests for different doses of IB given (0.08 mg, 0.15 mg and 0.25 mg), was correlated to the grade of hyperreactivity (PD20 dose). No or only a slight correlation was found between the grade of methacholine-induced hyperreactivity and the bronchodilator effects of the different doses of IB. These results indicate a lack of correlation between an anticholinergic bronchodilator effect and the grade of methacholine-induced bronchial hyperreactivity, or possibly an insensitivity of the above-mentioned methacholine test.
Highlights
Ipratropium bromide (IB) is a quaternary isopropyl derivative of the muscarinic antagonist atropine
The results of the methacholine test showed a skewed distribution for the PD20 dose between 0.125 and 20 mg/ml, where most patients had a value below 3.0 mg/ml (Figure 1)
Trials have previously been made to investigate the influence of several anti-asthmatic drugs on the bronchial hyperreactivity in both non-allergic and allergic bronchial asthma
Summary
Ipratropium bromide (IB) is a quaternary isopropyl derivative of the muscarinic antagonist atropine. Kraan et a1 (lo), in an investigation of patients suffering from allergic bronchial asthma, compared the effects of budesonide and terbutaline on the bronchial hyperreactivity as assessed by inhalation provocation tests with histamine and propanolol. They concluded that this hyperreactivity was improved by budesonide, but was temporarily increased following treatment with terbutaline. Sheppard et a1 ( 1 4 ) reported that inhaled atropine sulphate totally blocked cold air-induced bronchial asthma, but found that the doses needed were much higher than those required to relieve the resting bronchomotor tone or to block methacholine-induced bronchoconstriction. Poppius et a1 [13] treated patients with mild bronchial asthma with IB in doses 20-50 times higher than those known to have a marked effect on the resting bronchomotor tone in clinically stable bronchial asthma, and found that this treatment had no blunding effect on the bronchoconstrictive response to breathing of cold air during exercise
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