The effects of an inhaled beta(2)-adrenergic agonist on lower esophageal function - A dose-response study

Study objectives: Albuterol, a beta (2)-adrenergic agonist that is commonly used to treat asthma, reduces bronchial smooth muscle tone. The pharmacody namics of inhaled albuterol on esophageal function were studied in healthy volunteers. Design: A prospective, randomized, placebo-controlled, double-blind crossov er design. Setting: An academic medical center. Patients: Nine healthy, volunteers (five men, four women; age, 22 to 30 yea rs). Interventions: Albuterol (2.5 to 10 mg) or placebo was given via nebulizer. Volunteers were studied at two sessions, 1 week apart, using a 6-cm manome try assembly and a low-compliance pneumohydraulic pump. The percentage of l ower esophageal sphincter (LES) relaxation, the frequency of transient LES relaxations (TLESRs), and the amplitude, duration, and propagation velocity of esophageal contractions were measured at 5 and 10 em above the LES. Dep endent measures were evaluated using two-way, repeated-measures analysis of variance. Measurements and results: Albuterol therapy reduced LES basal tone in a dos e-dependent manner (baseline, 17.0 +/- 2.6 mm Hg; at 10 mg, 8.9 +/- 2.1 mm Hg; p = 0.01). The frequency of TLESRs was not different from placebo (not significant). Albuterol reduced the amplitude of esophageal contractions at 5 cm above the LES (baseline, 72.5 +/- 18.6 mm Hg; at 10 mg, 48.8 +/- 10.0 mm Hg; p < 0.05). A significant reduction in esophageal body contractile a mplitudes was noted at 10 em (F[1,6] = 7.05; p < 0.05). Conclusions: Inhaled albuterol reduced LES basal tone and contractile ampli tudes in the smooth muscle esophageal body in a dose-dependent manner. Inha led beta (2)-agonists may increase the likelihood of acid reflux in a subse t of patients who receive cumulative dosing.