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Cardioselective beta blocker treatment in patients with reversible airways disease
Beta adrenergic blocking (B-B) drugs have major beneficial effects in hypertension and certain cardiac disorders .
However, B-B drugs are generally considered contraindicated in patients with reversible obstructive airway diseases (OAD) such as asthma and COPD with a reversible component. Salpeter et al of the Santa Clara Valley Medical Center In San Jose, CA reviewed the Cochrane Airways Group Database to assess studies of the effects of currently used more cardioselective B-B drugs on mild to moderate OAD. Theyanalyzed the results in controlled studies comparing airflow patterns in individuals with OAD started on cardioselective B-B drugs vs added placebo.
Based upon findings in 19 studies, they found that use of a single dose of cardioselective B-B agents resulted in a small (8%) mean decrease in baseline FEV-1. However, there was a 14% greater mean increase in bronchodilator response to inhaled beta-agonists in such individuals when compared to that seen in those taking placebo instead of the B-B agents. After use of these B-B agents by asthmatics for a few days to several weeks, there was no significant decrease in FEV-1, no increased asthmatic symptoms and no increase in the use of beta-agonist inhalers. Use of cardioselective B-B drugs without intrinsic sympathomimetic activity was followed by an increased (13%) response to inhaled beta agonists, a response not seen following use of B-B with intrinsic sympathomimetic activity.
EDITOR'S COMMENTS
It is generally recognized that the recently developed B-B which are more selective for the beta 1 adrenergic pathways in the heart (cardioselective) present less potential problems for asthmatics than do the earlier, less selective. B-B agents such as propanolol which affects both the beta-1 and beta-2 pathways. The analysis described above concluded that at least short-term use of these cardioselective B-B drugs does not aggravate mild-moderate asthma.
As stated by the authors, their analysis does not permit comment about tolerance of these drugs by those with more severe asthma or whether use of these drugs affects the frequency of acute asthmatic exacerbations. Their puzzling finding of an increased bronchodilator response to inhaled beta- 2 agonists in those taking B-B agents which have no intrinsic sympathomimetic activity is of interest but of only limited clinical relevance.