retention enema

Polystyrene sulfonates are administered orally (with a meal) or rectally, by retention enema.

They consist of polystyrene sulfonate resins attached to a cation and are administered either orally or by retention enema to patients who are at risk of developing hyperkalaemia (abnormal high serum potassium levels).

The pharmacokinetics of rhein have not been intensively studied in humans, but at least one study in healthy male volunteers found that rhein was better absorbed from oral administration of rhubarb than from a retention enema.