Phosphate binder

 ( Nephrology Procedures ) 

Phosphate binders are 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.

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Mechanism of action 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.

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Medical use For people with chronic kidney failure, controlling blood plasma phosphate is important because it is associated with bone pathology and regulated together with serum calcium by the parathyroid hormone (PTH).

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Adverse effects Calcium carbonate

• GI effects (nausea, vomiting, constipation)
• Risk of cardiovascular calcification
• Risk of hypercalcemia

Lanthanum carbonate

• GI obstruction
• Bile duct obstruction
• Hepatic impairment
• No hypercalcemia risk

Sevelamer carbonate

• GI effects (nausea, vomiting, constipation, flatulence)
• No hypercalcemia risk

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Choice of agent There have been limited trials comparing phosphate binders to placebo in the treatment of hyperphosphatemia in people with chronic kidney disease. When compared with people receiving calcium-based binders, people taking sevelamer have a reduced all-cause mortality.

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Types

+ Summary of Common Oral Phosphate BindersBurtis, C.A.; Ashwood, E.R. and Bruns, D.E. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 5th Edition. Elsevier. pp1552 ! Phosphate Binder !! Brands !! Advantages !! Disadvantages
Risk of aluminum toxicity
Requires frequent monitoring-extra cost
Calcium containing-potential risk of hypercalcemia and ectopic calcification
Parathyroid hormone oversuppression
Gastrointestinal side effects
Efficacy pH dependent
Calcium containing-potential risk of hypercalcemia and ectopic calcification
Parathyroid hormone oversuppression
Gastrointestinal side effects
Large tablets & capsules, nonchewable formulation
Relatively costly
High pill burden
Large tablets, nonchewable formulation
Gastrointestinal side effects
Binds fat-soluble vitamins
Relatively costly
Gastrointestinal side effects
Larger tablet size may cause choking if not chewed well
Ferric Citrate	Auryxia	Iron based	Very costly
			Tablets can be toxic to young children
			Stool discoloration - may turn them black, obscuring intestinal bleeding

• Calcium acetate/magnesium carbonate

1. Lederer E, Ouseph R, Erbeck K. Hyperphosphatemia, eMedicine.com, URL: Hyperphosphatemia: Practice Essentials, Background, Pathophysiology, Accessed on July 14, 2005.

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External links

• High Phosphate Control - Official Fosrenol Homepage
• Phosphate Binders: What Are They And How Do They Work? - American Association of Kidney Patients*
• Phosphate Binders - National Kidney Foundation
• Phosphate Binders - Northwest Kidney Centers - a center that provides services for people with ESRD in the Seattle area.
• High Phosphate - Phosphorus Control - Information for healthcare professionals on the treatment and management of hyperphosphatemia

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Common Phosphate Binders

• Lanthanum - medlineplus.org
• Sevelamer - medlineplus.org
• Sevelamer - Renvela.com

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