What Is A Potassium Binder

  • Shiyi Liang Medical Biosciences, Imperial College London

Potassium is a vital element for your body and health, but an over amount of potassium can cause trouble to your body. Potassium binder is a kind of medication that is given to lower the level of potassium in the body when you have a high level of potassium. 

In this article, we will reveal more truths about potassium binders for you to understand this kind of drug better. 

Introduction 

Potassium is a vital element needed by the body. It can also be called an electrolyte because it appears in its ion form, with a positive charge, when present in the body. It is important for regulating the electrical activity of cells, including nerve cells and muscle cells. It is essential for normal muscle contraction, including the heart muscle. Potassium also helps relax blood vessels to reduce blood pressure. As a solute, it balances the water potential inside and outside of the cells and helps in waste removal and nutrient inflow.1 

A potassium binder is a pharmaceutical agent designed to bind the excess potassium in the gastrointestinal tract, reducing its absorption and facilitating its elimination from the body. The primary purpose of a potassium binder is to manage hyperkalemia, a medical condition characterized by abnormally high levels of potassium in the blood.2 

Hyperkalemia and its consequences 

The average normal potassium level in adults is between 3.5 and 5.0 millimoles per liter (mmol/L) and any values above that can be regarded as hyperkalemia. There are many potential causes of hyperkalemia in your body. Scientists classified them into cellular redistribution, excess intake and decreased renal excretion. Cellular changes caused by intrinsic factors (cell injury and alpha adrenalin stimulation) and extrinsic factors (drug intake) can cause high potassium levels. An excess intake of potassium from food and a reduced secretion through urine can elevate potassium level. A reduced secretion could be related to impaired renal function.3

When the potassium level remains high in the body, uncomfortable symptoms appear. Considering the role of potassium, accumulated potassium may cause heart palpitations, shortness of breath, chest pain, nausea, or vomiting. Also it reduces muscle firing meaning patients experience muscle weakness and numbness.4 

Potassium binders and their mechanism of action

By binding to excess potassium, potassium binders act as gastrointestinal cation exchangers, preventing it from being absorbed into the bloodstream from the digestive system, thereby enabling the body to excrete the excess potassium through bowel movements.5 Hyperkalemia can arise as a complication of underlying conditions, such as Chronic Kidney Disease (CKD). Therefore, it is crucial that its treatment does not conflict with other medications or coexisting health conditions. Common potassium binders include sodium polystyrene sulfonate (SPS), calcium polystyrene sulfonate (CPS), patiromer, and sodium zirconium cyclosilicate (SZC). 

Sodium polystyrene sulfonate (SPS)

Sodium polystyrene sulfonate is an insoluble polymer cation-exchange compound that acts in the intestine. Potassium is replaced by sodium and is removed through feces. This has a slow action and SPS also targets other metal ions like calcium and magnesium in the body, so it is usually a second-line treatment.6 This drug can be taken orally or rectally. 

Sodium zirconium cyclosilicate (SZC)

Sodium zirconium cyclosilicate is an insoluble selective potassium binder which also acts in the gastrointestinal tract. Unlike SPS, SZC has rapid action and can effectively lower potassium levels after 1 hour when taken orally.7

Calcium polystyrene sulfonate (CPS)

Calcium Polystyrene Sulfonate is not absorbed by our body. Its pharmaceutical form can be cream or light-brown fine powder for oral or rectal distribution. CPS is considered safe for patients with chronic kidney disease. It is sometimes better than sodium polystyrene sulfonate because it supplements calcium and prevents sodium accumulation.8

Patiromer

Patiromer (Veltassa®) is also a non-absorbed compound that binds excess potassium and releases calcium ions for exchange It also has a higher binding capacity of potassium than some traditional potassium binders like SPS, meaning that it removes potassium more rapidly. Patiromer acts in the colon by increasing the excretion of potassium through faeces and thus lowering the blood potassium level. The time for Patiromer to show a significant effect in the body requires around 7 hours after being taken orally.9 

When these four options were compared based on clinical trial studies, scientists indicated that SPS is well-suited for short-term use due to its high safety and efficacy. Patiromer also demonstrates effectiveness in reducing potassium levels, but it has been associated with a higher occurrence of gastrointestinal side effects. For individuals with chronic kidney disease who require a comprehensive approach to balance their potassium levels, both SZC and CPS have shown positive effects. SZC, in particular, stands out as a versatile choice suitable for both short-term and long-term use.5

Common uses and prescription 

Potassium binders are primarily prescribed for the management of hyperkalemia, a medical condition characterised by elevated levels of potassium in the bloodstream. Hyperkalemia often occurs in individuals with conditions such as chronic kidney disease, heart failure, poor-controlled diabetes, and those taking medications that can increase potassium levels. Additionally, patients undergoing treatments like hemodialysis may require potassium binders to regulate their potassium levels4

Healthcare providers assess the patient's potassium levels through blood tests and consider their overall health and existing medical conditions. Prescription guidelines include determining the appropriate type and dosage of the potassium binder based on the individual's specific needs and the underlying cause of hyperkalemia. For example, the common dosage of SPS is from 15 g to 60 g and it is not recommended to take with hot food or food with high potassium as this decreases its efficacy.6

Regular monitoring of potassium levels is also crucial to ensure that treatment is effective and safe. Additionally, healthcare providers may adjust the treatment plan as necessary to accommodate changes in the patient's condition or medications.

How safe are potassium binders 

Potassium binders have several side effects. Some are mild, but some can be serious. Common mild adverse effects are mainly gastrointestinal discomforts: diarrhoea, nausea, vomiting, and loss of appetite. Several side effects include constipation, seizures, muscle weakness, abdominal pain, and irregular heartbeat.6 

Healthcare providers monitor the effectiveness of these medications through regular blood tests to ensure that they adequately reduce elevated potassium levels. Here, we will provide some information on the efficacy and side effects of the previously mentioned potassium binder examples. 

For Sodium polystyrene sulfonate (SPS), the clinical trial study data is less abundant to conclude an accurate efficacy. It is also related to gastrointestinal adverse events, meaning that patients with stomach and intestine diseases could have a higher risk of hospitalisation for serious gastrointestinal side effects due to this drug.10

Patiromer has more clinical trial results with patients, which showed a significant reduction of potassium level in patients that took patiromer compared to patients who took placebos. Patiromer has a lasting effect and patients can maintain normal potassium levels for around four weeks. There is no record of serious adverse events, but there are still side effects targeting the gastrointestinal tract like constipation, vomiting, and diarrhoea.10

Unlike SPS and Patiromer which can bind to other metal ions in our gut, Sodium zirconium cyclosilicate (SZC) is more selective to potassium. When SZC is taken 3-times daily, it reduces potassium level in blood within 48 hours, and once a day with a dosage of 5-10g can maintain a normal serum potassium level for over 14-28 days.10 This drug increases bicarbonate in blood, which can increase the pH of patients’ gut environment. As a result, other drugs which are reacting in a pH-dependent way may be affected, so it is suggested to take these drugs with at least a 2 hour gap.

Administration and dosage 

Potassium binders are designed to be taken orally or rectally. When taking orally, pharmaceutical companies recommend taking it as suspension in water but not in juice, as juice may contain potassium. Rectal use is preferred when gastrointestinal discomfort like vomiting is seen.11 The drug should remain in the colon for enough time according to the medicine product information sheet and instructions should be followed.6 

FAQ’s

What foods are high in potassium? 

Cantaloupe, honeydew melon, orange juice, and bananas are high in potassium. Also, green leaf vegetables, nuts, beans and winter squashes are excellent sources. 

Any advice on a low-potassium diet?

The NHS has published a “Potassium lowering dietary advice” guideline for reference. It offered potassium lowering cooking tips like boiling the food in a large amount of water before cooking and discarding the water. It also provided low potassium alternatives for common food with high potassium. For example, limiting dairy milk intake and replacing them with non-dairy milk like oat/rice milk. It also recommends meat as a better source of protein rather than nuts and several beans. You can find details in this link: Potassium lowering dietary advice-NHS

Summary

Potassium binder is a kind of drug designed for hyperkalemia, a condition where there is a high potassium level circulating in your body which can lead to painful symptoms. Mainly non-absorptive potassium binders do have their place in the human gut by binding to excess potassium and promoting its elimination through faeces.

References

  • Harvard School of Public Health. Potassium [Internet]. The Nutrition Source. 2019. Available from: https://www.hsph.harvard.edu/nutritionsource/potassium/
  • Clinic C. Potassium Binder [Internet]. Cleveland Clinic. 2023. Available from: https://my.clevelandclinic.org/health/treatments/24744-potassium-binder
  • Palmer BF, Clegg DJ. Diagnosis and Treatment of Hyperkalemia. Cleveland Clinic Journal of Medicine [Internet]. 2017 Jan 1;84(12):934–42. Available from: https://mdedge-files-live.s3.us-east-2.amazonaws.com/files/s3fs-public/Document/November-2017/palmer_hyperkalemia.pdf
  • National Kidney Foundation. What Is Hyperkalemia? [Internet]. National Kidney Foundation. 2016. Available from: https://www.kidney.org/atoz/content/what-hyperkalemia
  • Dong L, Xu W, Deng Y, Tan J, Qin W. Efficacy and safety of potassium binders in the treatment of patients with chronic kidney disease and hyperkalemia. European Journal of Pharmacology. 2022 Aug;175174.
  • Rahman S, Marathi R. Sodium Polystyrene Sulfonate [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2021 [cited 2022 Jan 7]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559206/
  • BNF is only available in the UK [Internet]. NICE. Available from: https://bnf.nice.org.uk/drugs/sodium-zirconium-cyclosilicate/
  • Yu MY, Yeo JH, Park JS, Lee CH, Kim GH. Long-term efficacy of oral calcium polystyrene sulfonate for hyperkalemia in CKD patients. Shimosawa T, editor. PLOS ONE. 2017 Mar 22;12(3):e0173542.
  • Bushinsky DA, Williams GH, Pitt B, Weir MR, Freeman MW, Garza D, et al. Patiromer induces rapid and sustained potassium lowering in patients with chronic kidney disease and hyperkalemia. Kidney International. 2015 Dec;88(6):1427–33.
  • Palmer BF, Carrero JJ, Clegg DJ, Colbert GB, Emmett M, Fishbane S, et al. Clinical Management of Hyperkalemia. Mayo Clinic Proceedings. 2020 Nov;96(3).
  • Calcium Polystyrene Sulfonate 99.934% w/w Powder for Oral/Rectal Suspension - Summary of Product Characteristics (SmPC) - (emc) [Internet]. www.medicines.org.uk. Available from: https://www.medicines.org.uk/emc/product/13345/smpc
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Shiyi Liang

Medical Biosciences, Imperial College London

Shiyi has several years of experience as a writer for health articles and science reviews. Shiyi has engaged actively in diverse research projects, spanning topics from neuroscience to endocrinology, demonstrating her meticulous approach and passion for research. She is eagerly anticipating more opportunities to delve into the realms of research and science. Furthermore, Shiyi is dedicated to creating informative scientific videos.

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