Effect of an oral beta2-adrenergic agonist on lower esophageal sphincter pressure in normals and in patients with achalasia

The effect of the beta₂-adrenergic agonist, carbuterol, was studied on the lower esophageal sphincter (LES) pressure in normals and in patients with achalasia. In normals, the mean LES pressure decreased from 23.1±6.2 mm Hg (mean±sem) to 16.0±5.0 mm Hg at a 4.0-mg dose of carbuterol (P<0.05). In patients with achalasia, the mean LES pressure decreased from 50.1±5.1 mm Hg to 22.7±2.4 mm Hg after a 4.0-mg dose of carbuterol (P<0.01). The duration of action following oral administration exceeded 90 min. These studies indicate that the LES in man has beta₂-adrenergic receptors that mediate a reduction in pressure. The magnitude of LES pressure reduction in patients with achalasia suggests that this drug may be of therapeutic benefit.