Physical adsorption of Enterosgel, like most other enterosorbents such as activated charcoal, silica and polymers.
The core structure of main active component of Enterosgel polymethylsiloxane polyhydrate (PMSPH) comprises crumpled 2-dimensional sheets of tetrahedral -Si-O-Si-O-
The surface of nanoglobules has methyl (-CH3) and hydroxyl (-OH) groups bound to the atoms of silicon, Si.
The presence of hydrophilic groups (-OH) and hydrophobic groups (-CH3) makes this sorbent both hydrophilic and hydrophobic, which is rather unique compared with activated charcoal (mostly hydrophobic) and mineral sorbents such as silica (mostly hydrophilic). It allows PMSPH adsorb both hydrophilic and hydrophobic substances from aqueous solution.
The porous structure of polymer hydrogels such as PMSPH has been assessed by Gun’ko et al. (2007). The specific surface area of PMSPH is around 200 m2/g (dry weight). It has both micropores (below 2 nm in diameter) and mesopores (between 2 and 50 nm in diameter), with the mean mesopore diameter of 20 nm, which allows retention of small molecules in micropores and large biomolecules in mesopores. The surface area comprises almost equal contribution of both micro- and mesopores.
The Enterosgel® suspension of 10 g has therefore a surface area of approximately 2000 m2, which is sufficiently large to adsorb significant amount of substances of different molecular weight.
In vitro experiments described in Nikolaev, 2010 and Gun’ko et al., 2007, evaluated the adsorption capacity of PMSPH towards substances of different molecular weight in comparison with other materials used as enterosorbents such as activated charcoal and silica. It has been found that although the adsorption capacity of activated charcoal enterosorbents for small molecular weight substances tested (in the range from 60 Da (urea) to 1355 Da (vitamin B12) is significantly higher than that of PMSPH, the results were reverse for adsorption of large molecules of proteinaceous origin tested, from 23.3 kDa (trypsin) to 150 kDa (immunoglobulin G), with Enterosgel® paste showing 4-14 times higher adsorption capacity than the best activated charcoal and comparable values for adsorption of lipopolysaccharide, LPS calculated per daily dose.
Since the dose recommended for oral administration of PMSPH is substantially larger than that for activated charcoal by weight (approximately 3 times), the adsorption capacity of a daily dose of PMSPH towards small molecular weight substances becomes comparable to that of the daily dose of the latter.
The reason for the difference in the dosage between the two sorbents is the difference in their apparent density (activated charcoal has much lower apparent density hence the volume of the same weight of activated charcoal is about 3 times larger than the volume of PMSPH of the same weight).
The mechanism of this phenomenon has been discussed but there are no conclusive data to support it.
Enterosgel® does not incorporate any medicinal substance, or animal tissues, or blood components.