Medicines based on maghemite for the simultaneous reduction of gastrointestinal sodium reabsorption of phosphate and

The invention includes a substance based on nanocrystalline maghemite having a crystal size between 0.5 and 4 nm, which is smaller is defined five percent by weight of the total iron a magnetite content by the content of divalent iron ions and the transport of sodium and simultaneously phosphate in the gastrointestinal intestinal wall reduced from the gastrointestinal contents into the bloodstream and thus improve the imbalance of electrolytes and water and mineral balance in patients with impaired renal function when administered orally in combination with suitable pharmaceutical excipients.