Effect of Sildenafil on hypertensive lower oesophageal sphincter

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.