Phosphate binders are medications used to reduce the absorption of dietary phosphate; they are taken along with meals and snacks. They are frequently used in people with chronic kidney failure (CKF), who are less able to excrete phosphate, resulting in an elevated serum phosphate.

These agents work by binding to phosphate in the GI tract, thereby making it unavailable to the body for absorption. Hence, these drugs are usually taken with meals to bind any phosphate that may be present in the ingested food. Phosphate binders may be simple molecular entities (such as magnesium, aluminium, calcium, or lanthanum salts) that react with phosphate and form an insoluble compound.

Calcium carbonate

Calcium-based phosphate binders, such as calcium carbonate, directly decrease phosphate levels by creating insoluble calcium–phosphate complexes which gets eliminated in the feces.

Lanthanum carbonate

Non-calcium-based phosphate binders, including lanthanum carbonate, form insoluble complexes with phosphates in food, thereby reducing the amount of phosphate in the body.

Sevelamer carbonate

Sevelamer is an insoluble polymeric amine, which is protonated once in the intestines and this allows it to bind dietary phosphate. Phosphates are eliminated along with sevelamer, leading to a decrease in the body's phosphate levels.