Macrogol

solution used as a laxative used to cleanse the colon before colonoscopy, lower gastrointestinal series, or colon surgery. Constipation Macrogol 3350, often in combination with electrolytes, is used for short-term relief of constipation as well as for long-term use in constipation of various causes, including in people with multiple sclerosis or Parkinson's disease as well as constipation caused by pharmaceutical drugs such as opioids and anticholinergics. Whole bowel irrigation with macrogol is part of the bowel preparation before surgery or colonoscopy. Limited data also support its use for the treatment of fecal impaction. Popular types include: macrogol 3350, PEGylation Macrogols are also attached to biopharmaceutical drugs to slow down their degradation in the human body and increase their duration of action, as well as to reduce immunogenicity. This process is called PEGylation. ==Contraindications==

Contraindications for macrogol taken orally as a laxative are intestinal perforation, bowel obstruction, ileus, inflammatory bowel diseases, and toxic megacolon. Allergy to macrogol is rare, and usually appears as an allergy to an increasing number of seemingly unrelated products, including cosmetics, drugs that use it as an excipient, and peri-procedural substances such as ultrasound gel. ==Adverse effects==

Oral macrogol is generally well tolerated. Possible side effects include headache, bloating, nausea, allergies, and electrolyte imbalance, mainly hypokalaemia (low blood potassium levels) and hyperkalaemia (high blood potassium levels). Hyperkalaemia is not an effect of macrogol itself but of potassium salts which are usually part of macrogol formulations. == Interactions ==

The interaction potential is low. Absorption of other pharmaceutical drugs can be reduced because oral macrogol accelerates intestinal passage, but this is seldom clinically relevant. For antiepileptic drugs, such a mechanism has been described in rare cases. ==Pharmacology==

Mechanism of action as a laxative Macrogol is an osmotically acting laxative; that is, an inert substance that passes through the gut without being absorbed into the body. It relieves constipation because it causes water to be retained in the bowel instead of being absorbed into the body. This increases the water content and volume of the stools in the bowel, making them softer and easier to pass, as well as improving gut motility. ==Chemistry==

When sold for gut cleansing (and as a laxative), it is usually in combination with salts such as sodium bicarbonate, sodium chloride and potassium chloride to help mitigate the possibility of electrolyte imbalance and dehydration. Brand names include Cosmocol, Cololyt, Glycoprep, Laxido, Miralax, Molaxole, Movicol, and Osmolax. Polyethylene glycol-electrolyte solution is a fixed-dose combination medication sold under various brand names in the US, including Colyte, Gavilyte, Golytely, Nulytely, Moviprep, and Trilyte. Brand names available in the UK include Cosmocol, Klean-Prep, Laxido, Molaxole, Movicol, Plenvu, Transisoft, and Vistaprep. , polyethylene glycol 3350 is available in the US as a combination with sodium sulfate, potassium chloride, magnesium sulfate, and sodium chloride and sold under the brand name Suflave. It is indicated for cleansing of the colon in preparation for colonoscopy in adults. ==Research==

PEGylation can be PEGylated to form pegloticase, which improves its solubility at physiological pH, increases serum half-life and reduces immunogenicity without compromising activity. Upper images show the whole tetramer, lower images show one of the lysines that is PEGylated. ( PEG-uricase model from reference == References ==