What is the treatment for hyperkalemia using Kayexelate (sodium polystyrene sulfonate)?

Treatment of Hyperkalemia with Kayexalate (Sodium Polystyrene Sulfonate)

Kayexalate (sodium polystyrene sulfonate) is indicated for the treatment of hyperkalemia but should not be used as an emergency treatment for life-threatening hyperkalemia due to its delayed onset of action. 1

Mechanism and Administration

• Kayexalate is a cation-exchange resin that binds potassium ions in exchange for sodium ions in the distal colon, facilitating elimination of bound potassium in feces 2
• Standard dosing:
  • Oral: 15-60g daily, administered as 15g (four level teaspoons) one to four times daily 1
  • Rectal: 30-50g every six hours 1
• Onset of action is delayed (hours to days), making it unsuitable for emergency treatment of life-threatening hyperkalemia 2, 1

Treatment Algorithm for Hyperkalemia

Acute Life-Threatening Hyperkalemia (K+ >6.5 mEq/L or with ECG changes)

1. Stabilize myocardial cell membrane:

   • Calcium chloride (10%): 5-10 mL (500-1000 mg) IV over 2-5 minutes OR
   • Calcium gluconate (10%): 15-30 mL IV over 2-5 minutes 2

2. Shift potassium into cells:

   • Insulin with glucose: 10 units regular insulin with 25g glucose (50 mL of D50) IV over 15-30 minutes 2
   • Sodium bicarbonate: 50 mEq IV over 5 minutes (especially if metabolic acidosis present) 2
   • Nebulized albuterol: 10-20 mg over 15 minutes 2

3. Promote potassium excretion:

   • Diuresis: Furosemide 40-80 mg IV 2
   • Dialysis (most effective for severe cases) 2
   • Kayexalate: 15-50g orally or rectally (as adjunctive therapy, not for immediate effect) 2

Chronic or Recurrent Hyperkalemia (K+ >5.0 mEq/L)

1. For patients on RAAS inhibitors (ACEIs, ARBs, MRAs):

   • Consider potassium binders when K+ >5.0 mEq/L to maintain RAAS inhibitor therapy 2
   • Monitor potassium levels closely 2

2. General management:

   • Identify and address underlying causes (medications, diet, renal function) 2
   • Consider loop or thiazide diuretics to enhance potassium excretion 2
   • Kayexalate 15-60g daily in divided doses for ongoing management 1

Safety Considerations and Limitations

• Serious adverse effects: Intestinal necrosis and other serious gastrointestinal events have been reported with Kayexalate use, with or without sorbitol 1, 3, 4
• Mortality rate of 20.7-33% has been reported in cases with gastrointestinal adverse events 3, 4
• Risk factors for adverse events include:
  • Uremia
  • Hypertension
  • Post-transplantation status 3
• Electrolyte disturbances: Kayexalate is non-selective and may cause hypomagnesemia and hypocalcemia 2
• Drug interactions: Other oral medications should be taken at least 3 hours before or after Kayexalate 1
• Contraindications:
  • Hypersensitivity to polystyrene sulfonate resins
  • Obstructive bowel disease
  • Neonates with reduced gut motility 1

Newer Alternatives

• Newer potassium binders have better efficacy documentation and improved palatability 2:
  • Patiromer sorbitex calcium (Veltassa)
  • Sodium zirconium cyclosilicate (SZC; Lokelma) 2
• These newer agents should be considered for chronic hyperkalemia management, especially when optimized diuretic therapy and correction of metabolic acidosis are insufficient 2

ECG Monitoring

• ECG changes with increasing potassium levels include:
  • Peaked T waves (earliest sign)
  • Flattened or absent P waves
  • Prolonged PR interval
  • Widened QRS complex
  • Deepened S waves
  • Merging of S and T waves
  • Eventually sine-wave pattern, idioventricular rhythms, and asystolic cardiac arrest 2