Last update and review: July 10, 2020.
Short summary.
Simethicone is an effective defoaming agent both in vitro and in vivo. Gas bubbles coalesce and are dispersed by means of its surface action. Clinically, it has been shown to be effective in the treatment of patients with symptoms of gastrointestinal gas and bloating and in patients with postoperative abdominal distention.
Based on a 1968 article by Rider (1).
Experiences with the use of simethicone.
“7% of patients exhibited a multitude of tiny, tenacious bubbles, probably representing small air-pockets surrounded or held together by adherent mucus in the stomach”.
Rider found that approximately 7% of patients undergoing routine gastroscopic examination in his practice exhibited “a multitude of tiny, tenacious bubbles, probably representing small air-pockets surrounded or held together by adherent mucus in the stomach”. “The presence of these bubbles was so extensive that it prevented a complete examination, since the mucosa could not be visualized adequately.” Simethicone was very effective in abolishing this condition. Forty mg may be given orally in a lactose tablet prior to gastroscopy.
After simethicone, there is an almost instantaneous obliteration of the bubbles.
Rider, 1968 (1):
There is an almost instantaneous obliteration of the bubbles. In some patients, frothy bubbles may be seen regurgitating through the pylorus or through a gastroenterostomy stoma, and it can be observed that the bubbles or froth disappear promptly upon contact with the gastric mucosa which has been exposed to simethicone.
There is clinical evidence indicating that simethicone is effective in relieving symptoms in patients with GI gas and bloating.
Rider, 1968 (1):
There is a good deal of clinical evidence indicating that simethicone is effective in relieving symptoms in patients with GI gas and bloating, and there is objective evidence, as demonstrated by simple roentgenograms of the abdomen, to show a decrease in gas shadows following the use of this agent.
“The majority of patients who complain of intestinal gas and bloating do not have organic diseases.”
The majority of patients who complain of intestinal gas and bloating do not have organic diseases of the gastrointestinal tract. The most common cause appears to be air swallowing, accompanied by an inability to eliminate effectively the gas either by belching or by passing flatus. Every time one eats, drinks, or swallows saliva, atmospheric air enters the stomach. Spasm in the gastrointestinal (GI) tract, especially at the sphincters, impedes the normal passage of gas.
Analysis: In our opinion, excessive production of intestinal gas by intestinal bacteria is a more important cause of flatulence and bloating. Altered absorption of abdominal gas is another plausible cause. Rider further described the latter in his article.
Rider, 1968 (1):
An- other factor may be that the gas present in the GI tract may be trapped by numerous small pockets of air surrounded by adherent mucus. There is evidence to show that the latter incident occurs. During gastroscopic examinations, not only have tenacious bubbles been observed in the stomach, but also regurgitation of bubbles through the pylorus and through gastroenterostomy stomas has been seen.
Silicones (simethicone) have a marked defoaming effect both in vitro and in vivo through thteir ability of changing the surface tension.
There is no question that silicones (simethicone) have a marked defoaming effect both in vitro and in vivo. They have the ability of changing the surface tension which prevents sticky materials from adhering to each other. This appears to be the basis of their physical action.
What is the primary mechanism of action of simethicone?
Rider, 1968 (1):
However, the primary mechanism of action is due to the effect of simethicone in breaking up the small air-pockets, allowing them to coalesce into a larger mass which is easier for the patient to expel, can only be presumed. There are other mechanisms of action which can be postulated. For example, it is possible that the liberated GI gas is more readily absorbed through the intestinal mucosa into the blood stream because of the change in surface tension and the reduction of adherent mucus. Further studies are indicated to determine other possible mechanisms of action.
Selected references:
1. Rider. Ann N Y Acad Sci. 1968;150(1):170-177.