Effect of theophylline, terbutaline, and their combination on the immediate hypersensitivity skin-test reaction

Methylxanthines and beta agonists can be expected to inhibit the antigen-induced hypersensitivity skin-test reaction by affecting cyclic 3', 5'-adenosine monophosphate (cyclic AMP) metabolism, yet in vivo studies produce conflicting results. The discontinuation of these drugs prior to skin testing may result in the exacerbation of asthmatic symptoms; however, if these drugs are maintained, the validity of the test remains in question. To determine the effect of these drugs on the skin-test response, 15 patients received theophylline, terbutaline, the combination, and placebo in a double-blind study. No statistically significant difference (p greater than 0.05) was found for the areas of wheal and flare in response to injected allergens or histamine, between placebo and theophylline, terbutaline, and their combination. A marginal decrease in wheal area in response to codeine following combination therapy was observed. Therapeutic theophylline and terbutaline serum concentrations were documented. There is no need to discontinue theophylline or terbutaline prior to skin testing.