polystyrene sulfonate (Kayexalate, Kalimate, Kionex)

Introduction

Tradename: Kayexalate. (sodium polystyrene sulfonate)

Indications

• non-life-threatening hyperkalemia

* use is controversial

Contraindications

• recent bowel surgery

pregnancy category = ?

safety in lactation = ?

Dosage

• 1 g/kg up to 15-60 g PO or 30-50 g
  • do not give with other oral medications
• retention enema (in 33% sorbitol)
  • 30-60 g rectally
  • hold for 30 minutes if possible
  • repeat every hour as needed
  • follow with sterile water enema to remove resin from bowel

Suspension: oral or rectal:

• 1.25 g/5 mL with sorbitol 33% & alcohol 0.3% (500 mL)

Pharmacokinetics

• not absorbed from GI tract
• binds K+ as it passes through the intestine
• onset of action:
  • 2-10 hours when given orally
  • 3-12 hours when given rectally
• rectal administration is less effective
• 50 grams reduces serum K+ apporoximately 0.5-1 meq/L

elimination via feces

Adverse effects

• common (> 10%)
  • constipation, loss of appetite, nausea/vomiting
• less common (1-10%)
  • fecal impactation, hypokalemia, hypocalcemia, hypomagnesemia, sodium retention
• risk of severe GI adverse effects
  • diarrhea
  • intestinal necrosis
    • colonic necrosis (rare)
    • risk is highest with 70% sorbitol
    • risk may be highest in elderly
    • no increased risk
  • intestinal ischemia
  • intestinal thrombosis
  • intestinal ulceration
  • intestinal perforation

Mechanism of action

• cation exchange resin that exchanges K+ for Na+
• each gram of resin binds up to 1 meq of K+ in exchange for 1-2 meq of Na+
• sorbitol is present to induce diarrhea, reducing the risk of fecal impactation

More general terms

• metabolic agent (metabolic modifier)

Database

• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=169893