sodium polystyrene sulfonate

Action and Spectrum

Actions and Spectrum: 

sodium polystyrene sulfonate (SPS) is a medication used to treat certain conditions related to electrolyte imbalances, specifically hyperkalemia (high potassium levels) in the blood. It functions as a potassium-binding resin, helping to lower potassium levels in the body. 

Action: 

The primary action of sodium polystyrene sulfonate is based on its ion-exchange properties. It contains sulfonate groups that can exchange sodium ions for potassium ions in the gastrointestinal tract. When administered orally or rectally, SPS passes through the digestive system and exchanges sodium ions for potassium ions, forming a complex that is eliminated from the body through feces. This process helps to reduce the potassium levels in the bloodstream. 

Spectrum: 

It explicitly targets potassium ions. It does not affect other electrolytes or substances like sodium, calcium, or magnesium. Its action is limited to binding and removing excess potassium from the body. 

Drug Interaction

Adverse Reaction

Frequency defined 

1-10% 

Vomiting 

Constipation 

Sodium retention 

GI disturbance 

Nausea 

Hypomagnesemia 

Hypokalemia 

Hypocalcemia 

Frequency not defined 

Gastrointestinal concretions (bezoars) 

Necrosis 

Gastrointestinal tract ulceration 

Black Box Warning

Black Box Warning: 

None 

Contraindication / Caution

Contraindication/Caution: 

Contraindication 

sodium polystyrene sulfonate (SPS) has several contraindications, which are conditions or factors that make its use inappropriate or potentially harmful.  

• Hypersensitivity: SPS should not be used in individuals with known hypersensitivity or allergy to sodium polystyrene sulfonate or its components. Allergic reactions may range from mild skin rashes to more severe symptoms like difficulty breathing or swelling. 
• Intestinal Necrosis: SPS is contraindicated in patients with a history of intestinal necrosis (tissue death) or other significant intestinal disorders. The use of SPS in these conditions can further damage the intestines and worsen the condition. 
• Bowel Obstruction: SPS should not be used in individuals with suspected or confirmed bowel obstruction. It may worsen the obstruction or impede the movement of the bowels. 
• Constipation: SPS should be used cautiously or avoided in patients with severe constipation or impaction history. The medication can potentially exacerbate constipation or lead to intestinal blockage. 
• Electrolyte Imbalance: SPS should be used cautiously in patients with electrolyte imbalances other than hyperkalemia (high potassium levels). It may affect the levels of other electrolytes, such as calcium, and further disrupt the electrolyte balance in these individuals. 
• sodium-Retaining States: SPS should be used cautiously in patients with conditions that promote sodium retention, such as congestive heart failure or edema. The medication contains sodium, and excessive sodium intake may worsen these conditions. 

Caution 

• Gastrointestinal Conditions: SPS should be used cautiously in patients with gastrointestinal conditions, such as gastric ulcer, diverticulitis, or inflammatory bowel disease. SPS may exacerbate these conditions or increase the risk of complications. 
• Edema: SPS should be used cautiously in patients with edema or fluid overload as it contains sodium. Excessive sodium intake may worsen edema or fluid retention. 
• Medication Interactions: SPS may interact with other medications, including certain antibiotics, antifungal agents (such as amphotericin B), or laxatives (such as sorbitol). These interactions can affect the efficacy or safety of either SPS or the interacting medication. Therefore, informing your healthcare provider about all your medications before starting SPS is essential. 
• Impaired Gastrointestinal Motility: SPS should be used cautiously in patients with impaired gastrointestinal motility, such as those with a history of severe constipation or bowel obstruction. It may further slow down bowel movements or worsen the condition. 
• Electrolyte Imbalance: SPS primarily targets hyperkalemia (high potassium levels). However, it may also affect other electrolytes, such as calcium. Patients with underlying electrolyte imbalances should be monitored closely during SPS therapy to ensure appropriate electrolyte balance. 
• Pregnancy and Lactation: Limited information regarding the safety of SPS use during pregnancy or breastfeeding is available.  

Pregnancy / Lactation

Pregnancy consideration:  

AU TGA pregnancy category: B2
US FDA pregnancy category: C 

Lactation:   

Excreted into human milk: Not known. 

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    
• Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

sodium polystyrene sulfonate (SPS) is a cation-exchange resin with pharmacological properties that allow it to bind potassium ions in the gastrointestinal tract. When administered orally or rectally, SPS exchanges sodium ions for potassium ions, forming a complex that is eliminated from the body through feces.

This action mechanism helps reduce serum potassium levels in cases of hyperkalemia. SPS is not absorbed systemically, and its effect is limited to the gastrointestinal tract. It does not affect other electrolytes or substances like sodium, calcium, or magnesium. The onset of action is relatively slow, typically requiring several hours for significant potassium reduction. 

Pharmacodynamics: 

Mechanism of action: The action of sodium polystyrene sulfonate (SPS) is based on its ion-exchange properties. SPS is a cation-exchange resin that binds potassium ions in the gastrointestinal tract, leading to their removal from the body. 

When administered orally or rectally, SPS passes through the digestive system without being significantly absorbed into the bloodstream. In the intestinal lumen, SPS exchanges sodium ions in its structure for potassium ions in the intestinal contents. This ion exchange process results in the formation of a complex between SPS and potassium. 

Once the SPS-potassium complex is formed, it is not absorbed by the intestines and remains within the gastrointestinal tract. It is then eliminated from the body through feces. 

By removing potassium from the body, sodium polystyrene sulfonate helps to lower serum potassium levels. This is particularly beneficial in cases of hyperkalemia, where there is an excess of potassium in the bloodstream. 

Pharmacokinetics: 

Absorption 

When administered orally, SPS is not significantly absorbed from the gastrointestinal tract. It functions primarily within the intestinal lumen, exchanging sodium ions for potassium ions. 

Distribution 

SPS does not distribute widely throughout the body because it does not undergo systemic absorption. Its effects are localized to the gastrointestinal tract, specifically the administration site. 

Metabolism 

SPS is not metabolized in the body. It acts as an ion-exchange resin and undergoes limited chemical changes within the gastrointestinal tract. 

Elimination and Excretion 

After binding potassium in the gastrointestinal tract, feces eliminates the SPS-potassium complex from the body. It is not excreted via the kidneys or undergoes significant renal elimination. 

Adminstartion

Administration: 

Oral administration 

Depending on the specific formulation and the patient’s condition, sodium polystyrene sulfonate (SPS) can be administered orally or rectally.  

• The oral form of SPS usually comes in a powder or granule form, which needs to be mixed with a liquid before administration. Commonly used liquids include water, syrup, or fruit juice. 
• Measure the prescribed amount of SPS powder or granules using a measuring spoon or cup.  
• Mix the SPS powder or granules thoroughly with the desired liquid to form a suspension or solution. Stir well until the mixture is evenly dispersed. 
• Drink the mixture immediately after preparation. It is crucial to consume the entire dose to ensure proper effectiveness. 
• Additional liquid may be given after the SPS administration to facilitate its transit through the gastrointestinal tract. 
• Follow any specific timing instructions your healthcare professional provides, such as taking SPS before or after meals. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: sodium polystyrene sulfonate 

Pronounced: [ SOE-dee-um-pol-ee-STEER-een-SUL-foe-nate ] 

Why do we use sodium polystyrene sulfonate? 

sodium polystyrene sulfonate (SPS) is primarily used to treat hyperkalemia, a condition characterized by high levels of potassium in the blood. It functions as a potassium-binding resin and helps lower the body’s potassium levels. 

• Hyperkalemia: SPS is commonly prescribed for managing hyperkalemia, significantly when other measures such as dietary restrictions, diuretics, or other medications have not effectively lowered potassium levels. It works by exchanging sodium ions for the potassium ions in the gastrointestinal tract, removing excess potassium from the body through feces.