Isoetharine Hydrochloride

Isoetharine Hydrochloride is hydrochloride salt of isoetharine which is β2-adrenergic receptor agonist. It can be used to give quick relief for bronchospasm and asthma. However, It may be potent in producing resistantce to β-adrenoceptor stimulants.

The α-ethyl group confers β2-selectivity, and the β-hydroxyl group and catechol nucleus makes this a direct-acting drug. It is susceptible to COMT metabolism; however, the α-ethyl group inhibits MAO. Therefore, one would expect some oral activity.

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 (β1-receptor) adverse effects and it has a low β2-receptor potency compared to newer β2-selective agonists. It has a 2- to 4-minute 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.