Polymethylsiloxane polyhydrate

Polymethylsiloxane polyhydrate (PMSPH) is a sorbent designed for binding toxic substances of different nature, pathogens and metabolites in the gastrointestinal tract and their excretion. PMSPH is a homogeneous paste-like mass of white or almost white color, odorless.

Enterosorption, enterosorbents

    To remove toxic substances from the body methods of Sorption detoxification are applied based on binding of toxic substances by sorbents:
Hemoperfusion - removal of toxic substances is carried out through the direct contact with blood .^[1] Enterosorption - (innovative method of intestinal adsorbtion) is a method of enteral adsorption based on binding of toxic substances by sorbents. This method has a long history: about 3,000 years ago, substances have been found empirically that are able to bind harmful substances in the gastrointestinal tract. Even in ancient Egypt coal was necessary for external and internal use. Along with coal, clay has also been used since ancient times. Medical properties of coal were noted by healers of the Ancient Egypt, Hippocrates of Cos and his students in the Ancient Greece. Only 2,5 thousand years after foundation of the first famous medical schools on the island of Kos, in the mid 1860s, the name of Hippocrates returned in the history of enterosorption. Hippocratos Yatzidis,^[2] a Greek physician added important new elements to the development of active enteral detoxification and, in particular, of enterosorption. In 1982, the term enterosorption was offered ^[3] to refer to the method of enteral sorption detoxification, while the sorbents used in this method are called enterosorbents. Until the late 1970s coal, clay and other natural sorbents had been used. Side effects caused by the use of coal and other natural clay sorbents have limited their use for a long period. Thus it stimulated the search for new synthetic enterosorbents. As a result, PMSPH, a new silicone gelly-like enterosorbent, was created.

History

PMSPH was synthesized in the late '70s to the early 80 's in the Institute of physical chemistry named after L.V. Pisarzhevsky in Kiev (I.B. Slinyakova, I.M. Samodumova),^[4] where since 1960 a theoretical basis for the formation of porous structure of organosilicon adsorbents with adjustable pore structure and chemical nature of a given surface had been developed and studies on synthesis of organosilicon adsorbents - porous polymers polyorganosiloxane had been conducted.

General Information

Polymethylsiloxane polyhydrate is a gelly-like polymeric organosilicon compound. The gel is dispersed in water to a particle size less than 300 microns in suspension. Microstructure Electron microscopical studies have revealed that the gel-forming matrix has a globular structure and consists of an ensemble of fused globules. The globules bound with siloxane linkages form pores.^[5] The pores are spaces between the globules filled with water. The pore sizes are restricted. Sorption isotherms for hexane and methanol show that the adsorbent has a mesoporous structure.^[5][6] Presence of methyl groups on the surface provides their hydrophobic properties.^[7] PMSPH particles tend to form a continuous network in the suspension to reduce interaction of the hydrophobic groups SiCH₃ with water. These particles can be viewed as 2D sheets rather than 3D solids. Aqueous suspensions of polymethylsiloxane polyhydrate are characterized by high viscosity.^[8]

Mechanism of action

PMSPH is not absorbed in the gastrointestinal tract and is excreted unchanged within 12 hours. A robust porous structure of the gel-forming matrix determines absorptive capacity of the mechanism of molecular adsorption and allows mostly to adsorb toxic substances and metabolites (e.g., bilirubin, protein breakdown products).^[9] Thanks to its gelly-like consistency, PMSPH: a) absorbs macromolecular toxic substances by a mechanism of precipitation in the gel (e.g., bacterial toxins);^[10] b) exhibits protective properties - elastic gelly-like drug particles form a layer on the mucosal surfaces. This layer protects the mucous membranes from exposure to various damaging factors, while its protective properties are manifested universally - in the intestine and on the mucosal surface of other organs. PMSPH absorbs toxic substances from the gastrointestinal tract as well as toxic substances (xenobiotics) trapped in the gastro-intestinal tract, from the surrounding environment. PMSPH also prevents reabsorption of toxins and metabolites spun into the lumen of the blood as well as transferred to the intestine with bile. PMS PH firmly binds and removes pathogenic bacteria.^[11] It should be noted that PMSPH possesses a pronounced ability to absorb lipopolysaccharide molecules. Large lipopolysaccharide molecules coprecipitate in the gel and are excreted.^[10] A daily dose of PMSPH binds 410 mg of Lipopolysaccharide (LPS),^[12][5] which has an extremely high biological activity. LPS can be found in the outer wall of gram-negative bacteria and is released only when the bacteria are destroyed, hence it is also called endotoxin (endo means "inside", inside the bacteria). The main reservoir of gram-negative microflora and lipopolysaccharide is the distal intestine.^[13]
Medical device Category

Notes

1. Giordano 1980.
2. Yatzidis 1964
3. Nikolaev V.G. et al. 1982, pp. 112–114
4. Slinyakova & Denisova 1988, p. 25
5. Nikolaev V.G. et al. 2011, p. 200
6. Slinyakova & Denisova 1988, p. 28
7. Slinyakova & Denisova 1988, p. 27
8. Gun'ko et al. 2007, pp. 130–141
9. Slinyakova & Denisova 1988, p. 52
10. Nikolaev V.G. 2010, p. 40
11. Grigoryev A.V. et al. 1988
12. Nikolaev V.G. 2010, p. 39
13. Helmut Brade 1999, p. 962

Bibliography

• Giordano, Carmelo (1980), Sorbents and Their Clinics Applications, Academic Press, ISBN 5-11-000266-5
• Slinyakova, I.B.; Denisova, T.I. (1988), Kremniy-organicheskiye adsorbenty. Polucheniye, svoystva, primeneniye (Organosilicon-based adsorbents. Preparation, properties, application)., Kiev: Naukova Dumka, ISBN 5-12-000224-2

• Yatzidis, Hippocrates (1964). "A convenient haemoperfusion micro-apparatus over charcoal". Proceedings of the European Dialysis and Transplant Association.
• Nikolaev, V.G; Strelko, V.; Korovin, JYu. (1982). Sorption methods of detoxification and immunocorection in medicine (in Russian) (Theoretical basis and practical use of method of enterosorption ed.). Kharkov. pp. 112–114.
• Gun'ko; Turov; Zarko; Goncharuk (2007). "Comparative characterization of polymethylsiloxane hydrogel and silylated fumed silica and silica gel". Journal of Colloid and Interface Science. 308: 142–156. doi:10.1016/j.jcis.2006.12.053.
• Nikolaev, Volodimir G. (2011). Mikhalovsky, S.; Khajibaev, A., eds. Enterosgel: A Novel Orgnosilicon Enterosorbent with a Wide Range of Med. Application (Biodefence (NATO Science for Peace and Security Series A Chemistry and Biology), Adv. Matherial and Methods for healths protection ed.). Netherlands: Springer. pp. 199–221. ISBN 978-94-007-0219-6.
• Helmut Brade (1999). Endotoxin in Health and Disease. New York: Taylor & Francis. p. 962. ISBN 0824719441.
• Nikolaev, V.G (2010). Enterosgel. Kharkov. p. 39. ISBN 978-966-425-006-8.
• Grigoryev, A.V.; Znamensky, V.M.; Bondarenko, L.G.; Kupchinskiy, L.G.; Samodumova, I.M. (1988). Prozorovskiy, S.V., ed. Adhesion of pathogenic microflora on siliconorganic sorbents (in Russian) (Immunobiologicals of the new generation and methods of their control ed.). Moscow. pp. 114–120.

External links

• National Library of Medicine - Medical Subject Headings
• Journal of Colloid and Interface Science (Volume 308, Issue 1, Pages 1-290; 1 Apr 2007))
• Biomed Experts. Experts in Sorption Detoxification