Effect of theophylline on allergen skin tests

The effect of theophylline on allergen-induced wheal and flare responses of 15 adults with atopy was studied in a double-blind, crossover study. After intradermal skin tests to determine baseline wheal and flare responses, subjects were assigned randomly to consecutive seven-day courses of theophylline 16 mg/kg/day (as Aminophylline USP) then of placebo, or the reverse. Subjects were tested with mixed weeds and mixed grasses allergens and with histamine diphosphate, codeine phosphate and a buffered saline control. Skin tests were repeated two hours after the last dose of theophylline or placebo in each treatment course, and serum theophylline concentrations were measured. The surface areas of the wheal and flare responses were measured by planimetry. No statistically significant difference (p greater than 0.05) was found between theophylline and placebo in the suppression of the allergen-induced wheal and flare response. Serum concentrations of theophylline were within the accepted therapeutic range. In therapeutic steady-state serum concentrations, theophylline does not significantly suppress allergen-induced wheal and flare response of atopic patients, and withdrawal of the drug before skin testing is unnecessary.