Combined vs. single-entity pharmacologic inhibition of induced asthma.

The capacity of single oral doses of theophylline, ephedrine and hydroxyzine, alone and in combination, to prevent antigen-induced changes in airways dynamics was compared in patients with seasonal asthma. Each of the individual components was significantly more effective than placebo. Combinations of theophylline-ephedrine and theophylline-ephedrine-hydroxyzine exerted a significantly greater protective effect than the other treatments. Treatment with theophylline-ephedrine-hydroxyzine was associated with fewer side effects than any other treatment, except hydroxyzine alone.