The term “enterosorption” was first defined as the net gain of substances into the alimentary canal and in the context of a method of sorption therapy using orally administered sorbent materials or “enterosorbents”, was first used in the Soviet Union.
Enterosorbents are a group of materials which include activated carbons or charcoals, inorganic minerals, polymeric and silicon-containing resins. More recently they have been termed oral or intestinal adsorbents.
The term enterosorption is used to describe the process in which an enterosorbent travels along the gastrointestinal tract during which time it can adsorb certain molecules, but itself is neither absorbed from the gut into the systemic circulation, nor metabolised and is thus excreted unchanged. Charcoal has been used medically for many centuries, but it is only since the 1940s that its gastrointestinal adsorbent capacity has been demonstrated. For acute poisoning activated charcoal use is the intervention of choice to eliminate the poison from the gastrointestinal tract (GIT) and prevent its absorption by the body. Enterosorbents derived from calcium montmorillonite clays, such as NovaSil have been shown to adsorb aflatoxin B1 in vitro and be clinically effective in decreasing biomarkers of aflatoxin in the blood. However, charcoal is limited to short-term use as they are potent non-selective adsorbents. Regular use of enterosorbents over a longer period to treat medical conditions associated with chronic intoxication where sequestration of gut of toxins produced by the body or from bacterial species could be beneficial to patients, require a different set of physicochemical characteristics than for acute poisoning treatment. These include a material that is safe to be used over the longer-term, which can still adsorb target molecules such as bacterial toxins but shows negligible interactions with medications and micronutrients.
Enterosgel is an enterosorbent with an excellent safety record for over 30 years in the CIS countries, where it has been used in newborns to the elderly. It is listed in the governmental guidelines to treat wide range of pathologies from acute intestinal infections to side effects of chemo- and radiotherapy. In Europe, Enterosgel is a class IIa medical device and recommended as a symptomatic treatment of acute diarrhoea and chronic diarrhoea associated with Irritable Bowel Syndrome (IBS). Recent clinical studies have confirmed that Enterosgel improves the outcome in children and adults with acute diarrhoea (gastroenteritis), chronic diarrhoea including IBS with diarrhoea (IBS-D) and therapy induced diarrhoea in cancer patients.
Enterosgel is an organosilicon compound, polymethylsiloxane polyhydrate (PMSPH) which is formed from methylsiloxane by polycondensation. It comprises microglobules which contain porous space filled with water; these connect into larger particles (<250 µm in size) forming a hydrogel. The gel is amorphous and insoluble in water. Owing to its gelatinous nature, Enterosgel has a unique porous structure with a specific surface area of 150–250 m2/g dry weight. It has pores in the microporous range (below 2 nm in diameter) but mostly wide mesopores and small macropores in the range from 2 nm up to 100 nm in diameter. Enterosgel is composed of PMSPH and water in the ratio of 70/30 by weight, which has been found experimentally to have the highest pore volume ca. 1.5–1.6 cm3/g.
Generally, enterosorbents are non-selective in their adsorption, however, Enterosgel is reported as having an unusual and unique adsorption profile, showing an increasing sorption capacity with the increase in the molecular weight of the solute. This characteristic could be advantageous in limiting the unwanted adsorption of small molecules such as pharmaceutical drugs. Previous studies by Bardakhivska, et al., have shown that Enterosgel has lower adsorption activity towards certain anti-tuberculosis and anti-HIV preparations compared to activated charcoal.
Although Enterosgel is used in many clinical applications, the main mechanism of therapeutic action is still not fully understood; it is thought to be molecular adsorption of biological toxins from the gut. In this article we investigated Enterosgels mechanism of action, by examining in vitro adsorption capacity for bacterial toxins and bile acids, and interaction with the selected pharmaceutical drugs Cetirizine and Amitriptyline hydrochloride, assessing Enterosgels potential as a supportive therapy in complex treatment of conditions associated with the build-up of toxins in the GIT.*
*Howell, C.A., Mikhalovsky, S.V., Markaryan, E.N. et al. Investigation of the adsorption capacity of the enterosorbent Enterosgel for a range of bacterial toxins, bile acids and pharmaceutical drugs. Sci Rep 9, 5629 (2019). https://doi.org/10.1038/s41598-019-42176-z