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Ipratropium bromide: bronchodilator action and effect on methacholine-induced bronchoconstriction
1Research Department, FFLl, Arbetarskyddsstyrelsen, National Board of Occupational Safety and Health, Solna, Sweden.
Summary
Higher doses of ipratropium bromide may benefit some asthma patients by improving bronchodilation and methacholine challenge tolerance. This study explored ipratropium bromide
Area of Science:
- Pulmonary Medicine
- Pharmacology
Background:
- Asthma is characterized by bronchial hyperreactivity.
- Ipratropium bromide is a common bronchodilator used in asthma management.
Purpose of the Study:
- To investigate the effects of different dosages of ipratropium bromide on basal bronchial tone and methacholine-induced bronchoconstriction in asthmatic patients.
- To compare the efficacy of ipratropium bromide delivered via metered-dose inhaler (MDI) versus powder capsules.
Main Methods:
- A placebo-controlled, double-blind study was conducted with 10 asthmatic patients.
- Patients received ipratropium bromide (80 and 200 micrograms) or placebo.
- Bronchial reactivity was assessed using methacholine challenge before and after treatment.
- Drug delivery methods included MDIs and powder capsules.
Main Results:
- Both dosages of ipratropium bromide demonstrated bronchodilator effects and protected against methacholine-induced bronchoconstriction.
- The higher dosage (200 micrograms) showed a slightly more pronounced bronchodilation with powder capsules compared to MDI.
- Some patients experienced greater bronchodilator effects and improved methacholine tolerance with the higher ipratropium bromide dosage.
- Two patients showed no bronchodilator effect but significant protection against bronchoconstriction.
Conclusions:
- A higher than usual dosage of ipratropium bromide may benefit certain asthma patients.
- Anticholinergic effects on the bronchi can occur even without a significant basal bronchodilator effect.