Phosphate Binders 101
Mindy McCullough, MS, RD, LDN
Phosphate binders (also called phosphorus binders) are often a necessity for people with End Stage Renal Disease (ESRD) on dialysis and sometimes are required for those with Chronic Kidney Disease (CKD) pre-dialysis. Phosphate binders are taken with meals to stop the body from absorbing some of the phosphorus in your food.
Phosphate binders are taken about 5-10 minutes before you eat a meal or snack. Some people prefer to take them immediately after eating, which is also effective. Phosphate binders work by binding phosphorus from foods in the stomach and the gastrointestinal (GI) tract. The phosphorus is then passed through the stool out of the body. Phosphorus binders do not bind all the phosphorus from foods. It has been estimated that they bind about 50% of the phosphorus from the foods we eat leaving the rest to be absorbed into the blood stream.
Why Do We Need Phosphate Binders?
Being compliant with a renal diet plays a major part in controlling serum phosphorus levels; however, even the most compliant person will still consume phosphorus daily because phosphorus is found in almost all the foods we eat. We absorb about 30-40% of phosphorus from plant-based protein foods and 50-60% from animal-based protein foods. Phosphorus is extremely prevalent in our food supply as a preservative. Our bodies readily absorb approximately 90-100% of phosphorus in preservative form. Dialysis only removes approximately 250mg-900mg of phosphorus per dialysis treatment. Due to this, most dialysis patients need to take phosphate binders with meals and snacks to help remove phosphorus before it is absorbed into the blood stream.
What are the Consequences of Uncontrolled Phosphorus?
Some phosphorus is necessary for the body to function properly, but too much phosphorus present in the blood can cause damage to occur. Immediately, elevated phosphorus levels in the blood can cause itchiness and red eyes. Over time, bone health, the ability to heal, and heart health can all be negatively affected. Elevated levels of phosphorus in the blood signals for the release of parathyroid hormone to help balance the phosphorus and calcium in your blood. This pulls calcium from the bones, causing weak bones; and, if left untreated, may cause bone and joint pain. Excess phosphorus in the blood can also cause hardening of the arteries and blood vessels, which can lead to heart problems and blood flow issues. Controlling phosphorus with a low phosphorus diet, adequate dialysis, and phosphate binders are important for phosphorus control to prevent long-term health consequences.
Types of Phosphate Binders
There are multiple phosphate binders on the market. All phosphate binders work when taken as prescribed in combination with a low phosphorus diet. Phosphate binders come in different forms: pills, chewable tablets, liquid, and powdered. Each type of binder has a different binding capacity and in general acts like a magnet to bind with phosphorus in the stomach and GI tract. The amount of binder you need is dependent on the type you are taking and how compliant you are with the low phosphorus diet. Phosphate binders can be adjusted by a healthcare professional based off of lab results and personal tolerance of the binder.
The active ingredient in these binders is calcium.
Phoslyra is a liquid binder that needs to be measured before taken.
Starting dose: 10mL with each meal
PhosLo/Calcium-Acetate come in tablets or capsules.
Strength: 667mg/tablet or capsule
Starting dose: 2 tablets with each meal
Tums is an over the counter medications that can be used as a binder when needed.
Strength: 750mg or 1000mg/tablet
Starting dose: It is preferable that when using Tums as a binder, to purchase the 750mg or 1000mg Tums.
Common adverse reactions with calcium based binders are hypercalcemia, nausea, and diarrhea and/or constipation.
Sevelamer Based Binders
Sevelamer is the active ingredient in these binders. Renvela is the name brand name. Sevelamer Carbonate is the generic form. Sevelamer based binders act like a sponge and soak up the phosphorus in the GI tract.
Renvela/Sevelamer Carbonate come in tablets as well as powder form. The powder must be mixed with water according to the packet directions.
Strength: 800mg/tablet or 0.8g and 2.4g powder form packets
Starting dose: 1 to 2, 800mg tablets or 0.8g and 2.4g powder form packets with each meal
Renagel is available in tablet form.
Strength: 400mg or 800mg tablets
Starting dose: 1 to 2, 800mg tablets or 2 to 4, 400mg tablets with each meal
Common adverse reactions with sevelamer based binders are constipation, nausea, and diarrhea.
Lanthanum Based Binders
Lanthanum is the active ingredient in these binders.
Fosrenol is available as a chewable tablet and must be completely chewed before swallowing. It is also available in powder form and must be taken according to packet instructions.
Strength: 500mg, 750mg, and 1000mg tablets or 750mg and 1000mg powder packets
Starting dose: 1, 500mg tablet or 750mg and 1000mg powder packet with each meal
Common adverse reactions with Fosrenol are headaches, diarrhea, constipation, nausea, and hypocalcemia. It is not widely liked due to its hard, chalky texture.
Iron Based Binders
Over the last few years, two new binders have been introduced to the market. They are iron based and have a much better binding capacity than those already on the market.
Velphoro is sucroferric oxyhydroxide based. It is available as a chewable binder and can be broken or crushed and then swallowed. It can also be dissolved in a small amount of acidic juice or soda and taken that way.
Strength: 500mg/chewable tablet
Starting dose: 1, 500mg tablet with each meal
Auryxia is a ferric citrate based tablet. A possible benefit to taking Auryxia is that ferric citrate is absorbable and may help decrease the use of IV iron and erythropoietin stimulating agents (ESA) in dialysis patients.
Starting dose: 2, 210mg tablets with each meal
Common adverse reactions with iron based binders are dark stools and diarrhea.
Approximate Phosphorus Binding Capacity of Binders
Tips to Remember to Take Your Binders
Taking your binders as prescribed plays a big role in helping to keep your phosphorus levels within the recommended normal limits. Here are some tips and tricks to help you remember to always take your binders as prescribed when eating.
- Keep them where you normally eat. For example, if you always eat at the kitchen table, try to keep some binders in a pill box on the kitchen table or nearby so they are always in sight.
- Keep multiple little pill boxes filled with binders stashed in different places. Keep some in your car, purse, gym bag, work bag, etc. No matter what your plans are you will always have binders with you.
- Put a sign on your refrigerator or pantry reminding you to take your binders.
- If you are a person who enjoys using apps on your phone, there are apps that will alarm when you need to take your medications. You may not be able to always program it for the exact time you will eat, but it can still serve as a good estimated reminder.
- Utilize a pill box to organize your medications for the day/week.
Be sure to talk to your healthcare provider and dietitian about questions you may have regarding phosphate binders. Never adjust any medications without speaking to your healthcare provider first.
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