Is Senna or Miralax (Polyethylene Glycol) safe in a patient with impaired renal function and tumor lysis syndrome?

Safety of Senna and Miralax in Renal Patients with Tumor Lysis Syndrome

Miralax (polyethylene glycol) should NOT be used in patients with kidney disease and tumor lysis syndrome, while senna may be used with caution as it does not significantly impact renal function. 1

Miralax (Polyethylene Glycol) Safety

• The FDA label explicitly states: "DO NOT USE if you have kidney disease, except under the advice and supervision of a doctor" 1
• Patients with tumor lysis syndrome (TLS) already have compromised renal function due to:
  • Deposition of uric acid and calcium phosphate crystals in renal tubules 2
  • Electrolyte abnormalities (hyperkalemia, hyperphosphatemia) 2, 3
  • Potential pre-existing renal insufficiency which exacerbates TLS 3

Renal Considerations in TLS

• TLS is characterized by severe electrolyte abnormalities and frequently by acute renal failure 2
• The kidney normally excretes metabolic byproducts of tumor lysis, and pre-existing renal failure worsens metabolic derangements 2
• Indications for renal replacement therapy in TLS include:
  • Persistent hyperkalemia
  • Severe metabolic acidosis
  • Volume overload unresponsive to diuretic therapy
  • Overt uremic symptoms 4

Management Approach for Constipation in TLS Patients

• For patients with TLS and renal impairment requiring constipation management:
  • Senna is preferred over Miralax as it works through local action in the colon and has minimal systemic absorption 5
  • Adequate hydration (3 L fluid/m²/day) should be maintained to support both renal function and bowel movements 6
  • Monitor electrolyte levels closely, as both TLS and certain laxatives can affect electrolyte balance 5

Special Considerations

• In patients with severe renal impairment or uremic encephalopathy, renal replacement therapy should be initiated promptly 5
• Continuous renal replacement therapy (CRRT) is preferred over intermittent hemodialysis for hemodynamically unstable patients 5
• Avoid medications that may further compromise renal function or worsen electrolyte abnormalities 3

Pitfalls and Caveats

• Do not assume that all laxatives are equally safe in renal impairment
• Avoid phosphate-containing laxatives which could worsen hyperphosphatemia in TLS 6
• Remember that TLS can occur spontaneously or after initiation of chemotherapy, requiring vigilant monitoring of renal function 7
• Even with appropriate laxative therapy, patients with TLS may still require renal replacement therapy if renal function deteriorates 4