Original Article
Effect of Sildenafil Citrate on Postprandial Gallbladder Motility
Abstract
Objective: Sildenafil stimulates the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway through inhibition of type 5 phosphodiesterase. NO-cGMP pathway causes smooth muscle relaxation. The aim of this study is to evaluate the effects of sildenafil on gallbladder motility.
Methods: Twenty healthy male volunteers (21–35 years old) participated in this randomized, double blind, crossover, and placebo-controlled study. Oral sildenafil (50 mg) or placebo was randomly dispensed to each volunteer on two consecutive days. After the sildenafil or placebo, a special meal with a high fat content was administered. Gallbladder volume was measured using sonography preprandially and at 5, 15, 30, 60, 120 and 180 minutes postprandially.
Results: Sildenafil showed an inhibitory effect on gallbladder contraction in healthy volunteers that began at 30 minutes. Gallbladder volumes showed significant differences at 30 minutes following the test meal (approximately 50-60 min after the sildenafil intake), between placebo (15.4 ± 5.1 mL) and the sildenafil groups (19.3 ± 6.1 mL) (P < 0.05). In addition, gallbladder volume was significantly higher during the refilling phase in the sildenafil group (P < 0.05 at 180 min). Maximal contraction was achieved at 60 minutes in each group.
Conclusions: Sildenafil constituted a significant inhibitory effect on gallbladder discharge in healthy individuals when compared with placebo group. Because of this inhibitory effect, sildenafil consumption for long periods may potentiate risks of gallbladder disorders and gallstone formation resulting from disturbed gallbladder motility.
Key Points
* Sildenafil citrate is widely used for the treatment of erectile dysfunction because of its relaxant effect in vascular smooth muscle cells by inhibiting type 5 phosphodiesterase.
* It has been shown that sildenafil produces a similar effect in the smooth muscles of the esophagus, stomach, and rectum in the gastrointestinal tract.
* A comparable relaxant effect of sildenafil is expected in the gallbladder wall smooth muscle.
* Relaxation of the smooth muscle of the gallbladder wall decreases postprandial emptying in gallbladder.
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