Macrogol, also known as polyethylene glycol (PEG), is used as a medication to treat constipation in children and adults. It is also used to empty the bowels before a colonoscopy. It is taken by mouth. Benefits usually occur within three days. Generally it is only recommended for up to two weeks. It is also used as an excipient.Side effects may include increased bowel gas, abdominal pain, and nausea. Rare but serious side effects may include an abnormal heartbeat, seizures, and kidney problems. Use appears to be safe during pregnancy. It is classified as an osmotic laxative. It works by increasing the amount of water in the stool.Macrogol came into use as a bowel prep in 1980 and was approved for medical use in the United States in 1999. It is available as a generic medication and over the counter. In 2018, it was the 163rd most commonly prescribed medication in the United States, with more than 3 million prescriptions. Typically it is formulated together with electrolytes. Medical uses
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 multiple sclerosis and Parkinsons disease patients (an often-overlooked non-motor symptom) 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.
Hyperkalaemia is not an effect of macrogol itself but of potassium salts which are usually part of macrogol formulations. With excessive use, it can cause diarrhea. Interactions
The interaction potential is low. Resorption 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
Available forms
Macrogol is sold as a non-prescription preparation in the form of powder. 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 SoftLax, Purelax, MiraLax, Laxido, Glycoprep, CosmoCol, Movicol, Cololyt, Osmolax, and others.It is dissolved in water to create a clear and odorless solution which is then drunk.