Is icodextrin absorbed from the peritoneum during Peritoneal Dialysis (PD)?

Icodextrin Absorption from the Peritoneum During Peritoneal Dialysis

Yes, icodextrin is partially absorbed from the peritoneum during peritoneal dialysis, but at a significantly slower rate compared to glucose-based solutions, which is why it provides sustained ultrafiltration for long dwells. 1

Mechanism of Icodextrin Absorption

Icodextrin is a high molecular weight glucose polymer that works differently from traditional glucose-based PD solutions:

• Unlike glucose solutions that create ultrafiltration through crystalline osmosis, icodextrin works through colloid osmosis 2
• Approximately 40-45% of icodextrin is absorbed from the peritoneal cavity during a standard long dwell (16 hours) 3
• Absorption occurs primarily through lymphatic pathways rather than through peritoneal capillaries 1
• The high molecular weight of icodextrin significantly limits its absorption rate compared to glucose 2

Metabolism After Absorption

When icodextrin is absorbed from the peritoneal cavity:

• It is broken down by amylase into smaller metabolites, primarily maltose (G2) and maltotriose (G3) 3
• These metabolites accumulate in plasma during icodextrin use 3
• Plasma amylase levels typically decrease during icodextrin use 4
• Plasma sodium may decrease slightly (from ~139 to ~136 mmol/L) due to the osmotic effects of icodextrin metabolites 3

Clinical Implications of Icodextrin Absorption

Benefits:

• Provides sustained ultrafiltration for up to 16 hours, unlike glucose solutions that lose effectiveness after 4-6 hours 3
• Particularly beneficial for high and high-average transporters who rapidly absorb glucose 1
• Reduces glucose exposure and associated metabolic complications 5
• Maintains effectiveness during episodes of peritonitis 2

Potential Issues:

• Mild hyponatremia (usually clinically insignificant) 6
• Increased plasma osmolality due to circulating metabolites 5
• Interference with certain glucose monitoring devices that use glucose dehydrogenase pyrroloquinoline quinone methods 1
• Risk of severe hyperosmolar hyponatremia with excessive off-label use (more than one exchange per day) 6

Monitoring Considerations

When using icodextrin in PD patients:

• Be aware that certain glucose meters may give falsely high readings in patients using icodextrin, which has been associated with severe hypoglycemic events 1
• Monitor for hyponatremia, especially if using more than one icodextrin exchange daily 6
• Standard use (one exchange per day) typically causes only mild, clinically insignificant decreases in serum sodium 3
• Consider using continuous glucose monitoring systems that are not affected by icodextrin metabolites 1

Best Practices for Icodextrin Use

• Limit to one exchange per day (typically the long dwell - overnight for CAPD or daytime for APD) 1, 5
• Consider for patients with inadequate ultrafiltration using glucose-based solutions 1
• Particularly valuable for high and high-average transporters 1
• Useful during episodes of peritonitis when ultrafiltration may be compromised 2
• Can extend PD technique survival in patients who have failed dextrose-based dialysis 2

In conclusion, icodextrin's slower absorption rate compared to glucose is precisely what makes it valuable for long-dwell peritoneal dialysis exchanges, providing sustained ultrafiltration when glucose solutions would fail to maintain effectiveness.