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Attenuation of propranolol-induced bronchoconstriction by frusemide
J D Myers1, M A Higham, B H Shakur
1Department of Medicine (Respiratory Division), Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Thorax
|December 24, 1997
Summary
Inhaled frusemide significantly reduced propranolol-induced bronchoconstriction in asthma patients. This suggests frusemide may offer protection against indirect airway challenges, similar to sodium cromoglycate.
Area of Science:
- Respiratory Medicine
- Pharmacology
- Clinical Trials
Background:
- Inhaled propranolol induces bronchoconstriction in asthma via an unclear indirect mechanism.
- Inhaled frusemide is known to attenuate various indirect bronchoconstrictors.
- The study investigated frusemide's protective effect against propranolol-induced bronchoconstriction in asthma.
Purpose of the Study:
- To determine if inhaled frusemide can prevent bronchoconstriction caused by inhaled propranolol in patients with mild asthma.
- To compare the effects of frusemide and placebo on propranolol-induced airway narrowing.
Main Methods:
- Twelve mild asthma patients underwent three study days.
- Propranolol provocative concentration causing a 20% FEV1 reduction (PC20FEV1) was determined.
- Patients received either nebulized frusemide or placebo in a double-blind, randomized crossover design before propranolol challenge.
Main Results:
- Frusemide did not exhibit acute bronchodilator effects.
- Frusemide significantly reduced the maximum fall in FEV1 post-propranolol challenge (11.8%) compared to placebo (18.2%).
- The median difference in maximum % fall in FEV1 was 3.6%.
Conclusions:
- Inhaled frusemide attenuates propranolol-induced bronchoconstriction in asthma patients.
- This finding supports the hypothesis that frusemide and sodium cromoglycate share similar airway protective mechanisms.
- Frusemide's ability to block indirect bronchoconstrictor challenges is further evidenced.