Effect of sildenafil on gastric emptying in healthy adults.
OBJECTIVE
Phosphodiesterase type 5 hydrolyzes and inactivates cyclic guanosine monophosphate produced by the nitric oxide-stimulated guanylate cyclase. Sildenafil is a potent, reversible, and highly selective inhibitor of this phosphodiesterase. It causes smooth muscle relaxation by increasing intracellular concentrations of cyclic guanosine monophosphate. The aim of this study was to test the hypothesis that sildenafil alters gastric emptying and the intragastric distribution of food in healthy adults.


METHODS
Nine normal subjects (mean age 28 years, range 25-33) were given a placebo or a tablet of sildenafil (50 mg) at different times along with radio-opaque markers. A gastric emptying scan was used to calculate the t(1/2) for gastric emptying (the time taken for the initial radioactivity to fall by 50%). Intragastric food distribution was also assessed using the gastric emptying scan to calculate proximal gastric emptying t(1/2), the proximal volume (the highest activity value in the proximal stomach at any time point in the study), and the distal volume (the highest activity value in the distal stomach at any time point in the study. Gastric emptying of an indigestible solid meal was assessed by calculating gastric clearance of radio-opaque markers.


RESULTS
Sildenafil did not change total gastric emptying or gastric clearance of radio-opaque markers. It shortened the proximal T(1/2), decreased proximal volume, and significantly increased distal volume.


CONCLUSIONS
Sildenafil alters the intragastric distribution of food rather than causing gastric stasis.
Cho
Seung Hyun
SH
Division of Gastroenterology, Department of Internal Medicine, Yongdong Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Park
Hyojin
H
Kim
Jung Hwan
JH
Ryu
Young Hoon
YH
Lee
Sang In
SI
Conklin
Jeffrey L
JL
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors; D000328:Adult; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D005746:Gastric Emptying / Q000187:drug effects*; D006801:Humans; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D010879:Piperazines / Q000009:adverse effects / Q000494:pharmacology*; D011687:Purines; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D000068677:Sildenafil Citrate; D013670:Sodium Pertechnetate Tc 99m; D013270:Stomach / Q000000981:diagnostic imaging; D013450:Sulfones
D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D019275:Radiopharmaceuticals; D013450:Sulfones; D013670:Sodium Pertechnetate Tc 99m; D000068677:Sildenafil Citrate; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human