Immediate adverse reaction to aminophylline

We present a patient who experienced an immediate adverse reaction following intravenous administration of aminophylline. Skin prick, intradermal, and patch tests, RAST and indirect ELISA assays with aminophylline, theophylline and ethylenediamine were negative. A positive histamine release test was found only with ethylenediamine. Single-blind placebo-controlled challenges were positive with aminophylline and negative with theophylline. Our results suggest the reaction was a type I hypersensitivity reaction to ethylenediamine, but a nonimmune mechanism could not be excluded.