[The effect of adrenergic beta agonists on morbidity and mortality of asthma]

The frequency and severity of asthma are increasing, and since 1960 two "epidemics" of deaths have occurred. During the first one, in the 1960's, a beta-adrenergic agonist with low specificity administered in high doses was blamed and usually exonerated. During the second epidemics, in the 1975-85 period, fenoterol (a moderately selective beta-adrenergic agonist) administered in high doses was also blamed, but its noxious effects have not yet been definitely confirmed. The hypotheses concerning the potential hazards of beta-adrenergic agonists inhaled for long periods are interesting, as they incite us to think and possibly to revise our therapeutic approach, but they should not lead to an unfounded panic. These drugs may exert their potential noxious effects at several levels. They might increase the inflammation of the bronchi and result in tachyphylaxis, but these mechanisms do not seem to be responsible. When given in very high doses beta-adrenergic agonists produce hypokalaemia which is a cause of arrhythmias; this mechanism may explain some of the noxious effects of these drugs, but it has never been confirmed in clinical practice. Thus, the suggested causes of the increase in severity of asthma are multifactorial. From the data now available no firm conclusion can be drawn concerning the effects of this class of drugs, but they should incite physicians to caution and, above all, to a better prescription of anti-asthma treatments.