Background: Sildenafil shows an intense and prolonged inhibitory effect on the smooth muscle cells of corpus cavernosum arterioles by blocking phosphodiesterase-type 5, which inactivates the nitric oxide-stimulated cyclic guanosine monophosphate.
Aim: To investigate whether this inhibitory effect is also displayed on the musculature of the gastroduodenal tract.
Methods: In 16 normal subjects, antroduodenal motility was recorded by means of a low-compliance manometric system. Ten minutes after the appearance of a phase III of the migrating motor complex, a tablet of sildenafil 50 mg, dissolved in 20 mL of water, was infused in the gut of eight patients, or a placebo in the other eight patients, randomly and in a double-blind manner, continuing the recording for 90 min. The frequency and amplitude of antral and duodenal waves, measured during the first 60 min after infusion in the two groups, were compared statistically. In addition, the duration of antral and duodenal phases I, and the number of phases III occurring during the whole 90 min after infusion, were compared in the two groups.
Results: Antral and duodenal wave frequency and amplitude were significantly lower during the first 60 min after sildenafil administration. Both antral and duodenal phases I were significantly longer after sildenafil than after placebo, and the number of phases III which occurred during the 90 min after sildenafil was significantly lower than after placebo.
Conclusions: Sildenafil inhibits interdigestive motor activity of the antrum and duodenum.