What is the significance of using 7.5% icodextrin in peritoneal dialysis, particularly with no dextrose added?

Icodextrin in Peritoneal Dialysis: Composition and Clinical Significance

7.5% icodextrin is a glucose polymer solution used in peritoneal dialysis that contains NO dextrose, functioning through colloid osmosis rather than crystalline osmosis to provide sustained ultrafiltration during long dwells. 1

Composition and Properties of Icodextrin

• 7.5% icodextrin solution (Extraneal) contains 7.5 grams of icodextrin per 100 mL 1
• Additional components per 100 mL:
  • 538 mg sodium chloride
  • 448 mg sodium lactate
  • 25.7 mg calcium chloride
  • 5.08 mg magnesium chloride
  • pH 5.2 (range 5.0-6.0)
  • Osmolarity: 284 mOsmol/L 1

Mechanism of Action

Icodextrin works fundamentally differently from dextrose-based solutions:

• Colloid osmosis: Icodextrin creates ultrafiltration through a colloid-like osmotic effect rather than crystalline osmosis used by dextrose solutions 2
• Slow absorption: Icodextrin is absorbed from the peritoneal cavity much more slowly than dextrose, resulting in:
  • Longer duration of ultrafiltration
  • Lower carbohydrate load compared to medium (2.5%) and strong (4.25%) dextrose exchanges 2

Clinical Applications

Icodextrin is specifically designed for the long-dwell exchange in peritoneal dialysis:

• Used for the once-daily long-dwell exchange (8-16 hours)
• Particularly effective for overnight exchange in CAPD or daytime exchange in APD 2
• Produces net ultrafiltration exceeding that of 1.5% and 2.5% dextrose solutions
• Equivalent ultrafiltration to 4.25% dextrose solution but with better metabolic profile 2

Patient Selection for Icodextrin

Icodextrin is especially beneficial for:

• High and high-average transporters (patients with high peritoneal membrane permeability) 3, 4
• Patients experiencing ultrafiltration failure with conventional dextrose solutions 4
• Patients during episodes of peritonitis 2
• Patients who have failed dextrose-based dialysis 2

Important Considerations and Precautions

1. Interference with glucose monitoring: Icodextrin and its metabolites can interfere with certain glucose measurement devices:

   • Specifically interferes with glucose dehydrogenase-based monitors 3
   • Can cause falsely elevated glucose readings, potentially leading to inappropriate insulin dosing 3

2. Hyponatremia risk: Excessive off-label use (multiple exchanges) can cause hyperosmolar hyponatremia 5

   • Standard use is limited to one exchange per day
   • Using more than one icodextrin exchange daily is not recommended

3. Treatment failure: A small percentage of patients may not achieve adequate ultrafiltration with icodextrin despite being high transporters 6

Monitoring and Follow-up

When using icodextrin in peritoneal dialysis:

• Monitor ultrafiltration volume regularly
• Assess for fluid status and symptoms of volume overload
• Use appropriate glucose monitoring devices that are not affected by icodextrin
• Be aware that patients with high transporter status (determined by peritoneal equilibration test) are likely to have the best response 4

Icodextrin represents an important alternative to glucose-based solutions for peritoneal dialysis, particularly for patients who need enhanced ultrafiltration during long dwells without the metabolic disadvantages of high-concentration dextrose solutions.