Phosphate binders
Drugs taken with meals that trap phosphate from food in the gut, to control high phosphate in kidney failure.
What they are
In chronic kidney disease the kidney can no longer excrete phosphate. High phosphate drives secondary hyperparathyroidism, bone disease and vascular calcification. Binders combine with phosphate in food so it leaves in the stool. Options are calcium salts (calcium acetate, calcium carbonate), calcium-free agents (sevelamer, a polymer, and lanthanum carbonate, a metal salt), iron-based binders and, historically, aluminium, now avoided because it accumulates.
Mechanism of action
Taken with meals, they stay in the gut lumen and bind dietary phosphate into compounds that are not absorbed. Less phosphate enters the blood, serum phosphate and the calcium-phosphate product fall, and the stimulus to PTH secretion lessens. Calcium-free binders avoid adding a calcium load to people at risk of vascular calcification.
Target: Dietary phosphate in the gut lumen (no human receptor or enzyme)
Drugs in this class
- SevelamerA calcium-free, non-absorbed polymer taken with meals that binds dietary phosphate in people with kidney disease on…Dietary phosphate in the gut lumen (the drug is not absorbed and has no human receptor)
- Lanthanum carbonateA calcium-free phosphate binder, chewed with meals, for high phosphate in end-stage kidney disease. It shows up on…Dietary phosphate in the gut lumen (the drug acts locally and has no human receptor)
Others in the class
- Calcium acetate
- Calcium carbonate
- Ferric citrate
- Sucroferric oxyhydroxide
- Aluminium hydroxide (short term only)
Test yourself
Think of the answer, then tap the question to see it.
Why must phosphate binders be taken with meals?
They act inside the gut on the phosphate in food; taken on an empty stomach they have nothing to bind.
What is the advantage of sevelamer or lanthanum over calcium-based binders?
They do not add calcium, so they avoid hypercalcaemia and an extra calcium load in people at risk of vascular calcification.
Why are aluminium-containing binders avoided long term in kidney failure?
Aluminium is not excreted and accumulates, causing bone disease and encephalopathy.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - SEVELAMER CARBONATE powder, for suspension (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - LANTHANUM CARBONATE tablet, chewable (DailyMed (U.S. National Library of Medicine), 2026); Sevelamer: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2024).
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Representative model, for educational purposes only.