Isoetharine 3-agonist

One of the first 8-adrenoreceptor agonists used both currently and in the past as a bron-cholytic is epinephrine or adrenaline, isoproterenol, and especially ephedrine. In treatment and prevention of obstructive respiratory tract diseases, other j3-adrenoreceptor agonists also are used, such as isoetharine, terbutaUne, albuterol, metaproterenol, and also those described in this section—fenoterol (23.3.16), pirbuterol (23.3.22), and procaterol (23.3.25). 

Less selective adrenoceptor agonists such as adrenaline (epinephrine), ephedrine, isoetharine, isoprenaline and orciprenaUne are less safe, being more likely to cause cardiac arrhythmias, a-adrenoceptor activity contributes to bronchoconstriction but a-adrenoceptor antagonists have not proved effective in practice. 

Isoetharine Is dispensed as a solution only for Inhalation administration to treat reversible bronchospasm of asthma. It has fallen Into relative disuse, because with high doses, there Is a significant Incidence of cardiovascular (pi-receptor) adverse effects and It has a low p2-receptor potency compared to newer p2-selectlve agonists. It has a 2- to 4-mlnute onset of action when Inhaled and a duration of action of 3 hours. Isoetharine has adverse effects similar to those of EPI, Including palpitations, tachycardia, nausea and vomiting, dizziness, tremor, and headache. Isoetharine may cause decreased levels of theophylline when coadministered. Cardiovascular effects are a concern when Isoetharine Is taken with other asthma drugs. 

Selective beta2-adrenergic agonists have fewer side effects then epinephrine and are given by aerosol or as a tablet. These include albuterol (Proventil, Ventolin), isoetharine HCl (Bronkosol), metaproterenol sulfate (Alupent), sandeterol (Serevent), and Terbulahne SO4 (Brethine). 

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