How to Prescribe Sodium Polystyrene Sulfonate for Hyperkalemia
Critical Limitation: Not for Emergency Use
Sodium polystyrene sulfonate (SPS) should never be used as emergency treatment for life-threatening hyperkalemia due to its delayed onset of action (several hours to days). 1 For severe hyperkalemia (K+ >7.0-7.5 mEq/L) or ECG changes (QRS widening), use rapid-acting interventions: insulin/glucose (0.1 U/kg IV insulin with 25% dextrose 2 mL/kg), calcium gluconate (100-200 mg/kg slow IV with ECG monitoring), and sodium bicarbonate (1-2 mEq/kg IV push). 2
Dosing Regimens
Oral Administration
- Standard dose: 15-60 g daily, typically given as 15 g (four level teaspoons) one to four times daily 3, 1
- Suspend each dose in 3-4 mL of water or syrup per gram of resin 1
- Administer with patient in upright position 1
- Prepare suspension fresh and use within 24 hours; do not heat 1
Rectal Administration
- Dose: 30-50 g every 6 hours 3, 1
- Insert soft French 28 rubber tube 20 cm into rectum, administer as warm emulsion in 100 mL aqueous vehicle, flush with 50-100 mL fluid 1
- Retain as long as possible, then cleansing enema with non-sodium solution (up to 2 liters) 1
- Avoid rectal route in neutropenic patients 2, 3
Medication Separation Requirements
Administer SPS at least 3 hours before or after other oral medications (6 hours in gastroparesis) due to nonselective binding that reduces absorption of other drugs. 3, 1
Expected Efficacy
- In a randomized controlled trial of outpatients with CKD and mild hyperkalemia (K+ 5.0-5.9 mEq/L), 30 g daily for 7 days reduced potassium by 1.25 mEq/L versus 0.21 mEq/L with placebo (mean difference -1.04 mEq/L, P<0.001). 2, 3, 4
- Dose-response relationship: 15 g reduces K+ by 0.39 mEq/L, 30 g by 0.69 mEq/L, and 60 g by 0.91 mEq/L. 5
- Rectal administration is less effective (0.22 mEq/L reduction). 5
Contraindications
Do not prescribe SPS in patients with: 1
- Hypersensitivity to polystyrene sulfonate resins
- Obstructive bowel disease
- Neonates with reduced gut motility
- History of impaction, chronic constipation, inflammatory bowel disease, ischemic colitis, vascular intestinal atherosclerosis, previous bowel resection, or bowel obstruction 1
- Patients who have not had bowel movement post-surgery 1
Critical Safety Warnings
Gastrointestinal Necrosis Risk
Fatal intestinal necrosis, ischemic colitis, perforation, and bleeding have been reported with SPS, with overall mortality rate of 33% in some series. 2, 3 Risk factors include prematurity, history of intestinal disease/surgery, hypovolemia, and renal insufficiency. 1
- Never administer concomitantly with sorbitol 1
- Use only in patients with normal bowel function 1
- Discontinue immediately if constipation develops 1
Electrolyte Disturbances
- Monitor serum potassium, calcium, and magnesium regularly as SPS nonselectively binds these cations 3, 6
- Can cause hypocalcemia, hypomagnesemia, and hypokalemia 2, 3
- Each 15 g dose contains 1500 mg sodium 3
- May cause systemic alkalosis 3
Monitoring Protocol
- Verify elevated potassium with second sample to rule out pseudohyperkalemia from hemolysis 2, 3
- Monitor ECG and cardiac rhythm closely, especially if K+ elevated or QRS widening present 2, 3
- Check serum potassium, calcium, and magnesium at regular intervals during therapy 3
When to Use Alternative Agents
Newer potassium binders (patiromer or sodium zirconium cyclosilicate) are preferred for chronic hyperkalemia management because they have no reported fatal gastrointestinal injury, faster onset (1-7 hours), and allow continuation of RAAS inhibitor therapy. 3, 6 Consider alternatives for:
- Patients requiring chronic potassium management 3
- Those on maximum-tolerated RAAS inhibitor doses with K+ 5.0-6.5 mEq/L 3
- Moderate hyperkalemia (6.0-6.5 mEq/L) given SPS's limited efficacy 3