Background: Sildenafil relaxes the muscle cells of the penis arterioles by inhibiting phosphodiesterase-type 5 (PD-5), inactivating the nitric oxide-stimulated cyclic guanosine monophosphate. We investigated whether this effect of Sildenafil is also displayed on the muscles of the hypertensive lower oesophageal sphincter (LES).
Methods: In 14 patients with symptomatic hypertensive LES, oesophageal motility was recorded by means of a low-compliance manometric system with five manometric ports for the oesophageal body and a sleeve for the sphincter. After a basal period of 60 min a tablet of Sildenafil 50 mg (group A; seven patients) or one of placebo (group B; seven patients) ground and dissolved in 20 cc of water was infused in the stomach, randomly and in double-blind manner. Recording continued for a further 60 min. Sphincter tone and pressure wave amplitude were measured each minute and the values averaged for each 5-min period for the post-infusion period of 60 min. The values of the whole post infusion period, the lowest values among the 5-min periods (nadir values) and the values of the last 5-min periods were compared with the basal values in each group, and those of group A were compared with the corresponding values of group B.
Results: Sphincter tone and wave amplitude showed after Sildenafil a significant decrease comparable that of the basal period and the placebo. The inhibitory effect reached its maximum 10 min after the infusion and lasted approximately 1 h.
Conclusions: Sildenafil inhibits the lower oesophageal sphincter tone and pressure wave amplitude of patients with symptomatic hypertensive LES. These findings suggest a clinical application of PD-5 inhibitors in the treatment of spastic oesophageal motor disorders.