Study objectives: Albuterol, aβ
2-adrenergic agonist that is commonly used to treat
asthma, reduces bronchial smooth muscle tone. The pharmacodynamics of
inhaled albuterol on esophageal function were studied in healthy
Design: A prospective, randomized,
placebo-controlled, double-blind crossover design.
Setting: An academic medical center.
Patients: Nine healthy volunteers (five men, four women;
age, 22 to 30 years).
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
manometry assembly and a low-compliance pneumohydraulic pump.
The percentage of lower 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 cm above the LES. Dependent measures were
evaluated using two-way, repeated-measures analysis of variance.
Measurements and results: Albuterol therapy reduced LES
basal tone in a dose-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 amplitudes was
noted at 10 cm (F[1,6] = 7.05; p < 0.05).
Conclusions: Inhaled albuterol reduced LES basal tone and
contractile amplitudes in the smooth muscle esophageal body in a
dose-dependent manner. Inhaled β2-agonists may increase
the likelihood of acid reflux in a subset of patients who receive