Question

All of the following statements about B- adrenergic agonists used to treat asthma are correct EXCEPT? A. Inhaled β-agonists used in clinical practice are selective for β receptors at usual doses, but become less selective at escalating doses B. Inhaled β-agonists are functional antagonists of constriction and result in relaxation of the airway smooth muscle regardless of mechanism of constriction C. Repeated exposure to inhaled β-agonists results in up-regulation of the β receptors which allows for decreased doses over time D. Long acting β-agonists are not used for acute symptoms and are not intended as first-line therapy for worsening asthma E. Long acting β-agonists are effective in controlling night-time symptoms and exercise-induced symptoms

Answer 1

C. Repeated exposure to inhaled β-agonists results in up-regulation of the β receptors which allows for decreased doses over time is not correct. Repeated exposure to β-agonists can lead to down-regulation (desensitization) of β receptors, reducing their effectiveness over time, rather than up-regulation.