Kayexalate (Sodium Polystyrene Sulfonate) Dosing for Hyperkalemia
Critical Limitation: Not for Emergency Use
Kayexalate should NOT be used as emergency treatment for life-threatening hyperkalemia due to its delayed onset of action (several hours to days). 1 For acute severe hyperkalemia with ECG changes or potassium >6.5 mEq/L, use rapid-acting treatments first: IV calcium gluconate for membrane stabilization, insulin/glucose, and nebulized albuterol. 2, 3
Standard Dosing Regimens
Oral Administration
- Standard dose: 15 g to 60 g daily, administered as 15 g (four level teaspoons) one to four times daily 1
- Preparation: Suspend each dose in 3-4 mL of liquid per gram of resin (water or syrup) 1
- Timing: Administer at least 3 hours before or after other oral medications; patients with gastroparesis require 6-hour separation 1
- Administration: Patient must be in upright position 1
- Preparation note: Prepare suspension fresh, use within 24 hours, and do not heat as this alters resin exchange properties 1
Rectal Administration
- Standard dose: 30 g to 50 g every 6 hours 1
- Technique: After initial cleansing enema, insert large French 28 rubber tube 20 cm into rectum with tip in sigmoid colon 1
- Preparation: Administer as warm (body temperature) emulsion in 100 mL aqueous vehicle, flush with 50-100 mL fluid 1
- Retention: Retain as long as possible, then follow with cleansing enema using non-sodium containing solution (up to 2 liters) 1
Expected Efficacy
In patients with mild hyperkalemia (K+ 5.0-5.9 mEq/L), 30 g daily Kayexalate reduced serum potassium by 1.04 mEq/L more than placebo over 7 days. 4, 5 The practical exchange ratio is approximately 1 mEq potassium per 1 gram resin. 4, 6 Single-dose administration typically reduces potassium by less than 1 mEq/L. 7
Serious Safety Concerns and Contraindications
Absolute Contraindications
- Obstructive bowel disease 1
- Neonates with reduced gut motility 1
- Hypersensitivity to polystyrene sulfonate resins 1
High-Risk Situations Requiring Avoidance
- Patients who have not had bowel movement post-surgery 1
- History of constipation, impaction, or inflammatory bowel disease 1
- Ischemic colitis or vascular intestinal atherosclerosis 1
- Previous bowel resection or obstruction 1
Gastrointestinal Toxicity
Cases of intestinal necrosis (some fatal), bleeding, ischemic colitis, and perforation have been reported, particularly with concomitant sorbitol use. 1 Concomitant administration with sorbitol is NOT recommended. 1 The overall mortality rate associated with serious GI adverse events is 33%. 6
Electrolyte Monitoring Requirements
Monitor the following during therapy 1:
- Serum potassium: Risk of severe hypokalemia 1
- Calcium: Can be lost during treatment 1
- Magnesium: Can be lost during treatment 1
- Sodium: Each 100 g powder contains 100 mg (4.3 mmol) sodium, problematic in hypertension or fluid overload 6
Preferred Alternative Agents
Newer potassium binders (patiromer or sodium zirconium cyclosilicate) are superior to Kayexalate due to more predictable onset, better tolerability, and superior safety profiles. 2, 4, 6
Patiromer
- Onset: ~7 hours 2
- Dosing: 8.4 g once daily, titrate up to 25.2 g daily 2
- Mechanism: Binds K+ in exchange for Ca2+ in colon 2
Sodium Zirconium Cyclosilicate (Lokelma)
- Onset: ~1 hour 2, 4
- Initial dosing: 10 g three times daily for 48 hours 2
- Maintenance: 5-15 g once daily 2
- Mechanism: Highly selective K+ binding in small and large intestines 2
Clinical Context for Use
Kayexalate may be considered only when 6, 8, 9:
- Newer agents are unavailable or unaffordable
- Mild chronic hyperkalemia (K+ 5.0-5.9 mEq/L) requiring non-emergency management
- Patient has normal bowel function without contraindications
- Low-dose daily therapy (15-30 g) for secondary prevention in CKD patients on RAAS inhibitors
For chronic hyperkalemia in patients on RAAS inhibitors, prioritize maintaining cardioprotective and renoprotective therapy by using newer potassium binders rather than discontinuing RAAS inhibition. 2, 8, 9