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.
While most consumers find the taste of macrogol itself to be very mild and unobjectionable, the electrolytes contained in formulations for purging and cleansing give the solution an extremely salty and bitter taste.Polyethylene glycol-electrolyte solution is a prescription product sold under various brand names including Colyte, Gavilyte, Golytely, Nulytely, Moviprep, and Trilyte. Research
PEGylation
When attached to various biopharmaceutical medications (which are proteins), macrogol results in a slowed clearance of the carried protein from the blood. This makes for a longer-acting medicinal effect and reduces toxicity, and it allows for longer dosing intervals. It also reduces the proteins immunogenicity. Examples for PEGylated proteins include peginterferon alfa-2a and -2b, which are used to treat hepatitis C, pegfilgrastim, which is used to treat neutropenia, and pegloticase for the treatment of gout. Nerves and spinal cords
There is evidence demonstrating PEG-induced repair of specific nerve cells in animal models:

It has been shown that macrogol can improve healing of spinal injuries in dogs. One of the earlier findings is that macrogol can aid in nerve repair in earthworms. The subcutaneous injection of macrogol 2000 in guinea pigs after spinal cord injury leads to rapid recovery through molecular repair of nerve membranes. The effectiveness of this treatment to prevent paraplegia in humans after an accident is not known yet. Macrogol is being used in the repair of motor neurons damaged in crush or laceration incidents in vivo and in vitro. When coupled with melatonin, 75% of damaged sciatic nerves were rendered viable.