Background & aims: Sildenafil shows an intense and prolonged inhibitory effect on the smooth muscle cells of the human corpus cavernosum by blocking phosphodiesterase type 5 that destroys nitric oxide-stimulated cyclic guanosine monophosphate. We investigated if sildenafil possesses a similar effect on the esophageal musculature of patients with achalasia, where there is an impairment of nitric oxide production similar to that of functional impotence.
Methods: In 14 patients affected by achalasia with an esophageal diameter of </=5 cm, esophageal motility was recorded with a low-compliance manometric system. After a basal period of 30 minutes, a 50-mg tablet of sildenafil dissolved in water was infused in the stomach in 7 patients and one of placebo in the other 7 patients, randomly and in double-blind manner, continuing the recording for 60 minutes.
Results: Lower esophageal sphincter tone, residual pressure, and wave amplitude after sildenafil showed a significant decrease compared with both the basal period and the placebo group, with a marked interpatient variability. The inhibitory effect reached its maximum (about -50%) 15-20 minutes after the infusion and lasted <1 hour. Propagation of pressure waves was not modified by sildenafil.
Conclusions: Sildenafil inhibits the contractile activity of the esophageal musculature of patients with achalasia, decreasing lower esophageal sphincter tone and residual pressure as well as contraction amplitude.