Effect of a selective beta 2 adrenergic agonist and theophylline on skin test reactivity and cardiovascular...

Fenoterol, a selective beta 2-adrenergic agent, and aminophylline in the "therapeutic range" were compared with placebo for their inhibitory effect on skin test reactivity to allergens and histamine. Cardiovascular parameters were also assessed. A new, inexpensive micrometer adaptor to a tuberculin syringe was used to deliver allergens and histamine more accurately. No inhibition of skin test reactivity to antigens or histamine was found after a loading dose or after 1 wk of round-the-clock therapy with these bronchodilators. Although there was increased heart rate after 1 and 2 hr with fenoterol, there was no patient preference for one bronchodilator over the other. The results of this study point out some of the difficulties in trying to extrapolate in vitro findings to in vivo correlates since neither fenoterol nor therapeutic doses of theophylline interfere with immediate skin test reactivity.