Pulmonary function response to EDTA, an additive in nebulized bronchodilators

Background: Some nebulized bronchodilator solutions contain additives, such as EDTA, benzalkonium chloride (BAC), or bath. Objective: Although BAG-induced bronchoconstriction has been well documented in patients with asthma, there is no information on the effects of EDTA on FEV1 when inhaled in the amounts that would be administered during emergency department treatment of asthma, Methods: Eighteen subjects with stable asthma and airway responsiveness to methacholine were randomly assigned to inhale up to four 600-mug nebulized doses of EDTA, BAC (positive control), and normal saline (placebo) in a double-blind crossover manner on separate days. FEV1 was measured 15 minutes after each dose. Treatments were repeated every 20 minutes until FEV1 decreased by 20% or greater or a maximum of 4 doses were administered. Results: Mean +/- SD maximum percent decrease in FEV1 was 1.8% +/- 5.8% after EDTA, 16.6% +/- 13.9% after BAG, and 3.6% +/- 8.2% after placebo (P <.001); there was no significant difference between EDTA and placebo. Conclusion: The amount of EDTA contained in maximum recommended doses of nebulized bronchodilators does not induce bronchospasm. In contrast, BAC induces clinically important bronchospasm, which could decrease the efficacy of a bronchodilator during an emergency.