Can Myfortic (mycophenolic acid) cause ileus?

Can Myfortic (Mycophenolic Acid) Cause Ileus?

Yes, Myfortic (mycophenolic acid) can cause ileus and other severe gastrointestinal complications including small bowel obstruction. This is documented in clinical guidelines that specifically mention gastrointestinal disorders including severe constipation and small bowel obstruction/ileus progression as potential adverse effects of mycophenolic acid preparations 1.

Mechanism and Risk

Mycophenolic acid (MPA) is an immunosuppressant commonly used in solid organ transplantation to prevent rejection. While Myfortic was specifically developed as an enteric-coated formulation to reduce gastrointestinal side effects compared to mycophenolate mofetil (CellCept) 2, 3, it can still cause significant GI complications including:

• Gastrointestinal motility disorders
• Severe constipation
• Small bowel obstruction
• Ileus progression

The pathophysiology likely involves:

1. Local intestinal toxicity from MPA exposure in the gut lumen 4
2. Production of toxic metabolites (acyl-MPAG) by GI cells 4
3. Potential impact on intestinal motility

Evidence from Clinical Guidelines

The 2024 Diabetes Care guidelines specifically list "gastrointestinal disorders (severe constipation and small bowel obstruction/ileus progression)" as possible safety concerns for medications containing mycophenolic acid 1. This is particularly important as these complications can be severe and potentially life-threatening.

Additionally, the American Journal of Transplantation guidelines (2009) identify that mycophenolic acid can cause significant gastrointestinal issues, noting that both formulations (mycophenolate mofetil and enteric-coated mycophenolate sodium/Myfortic) are associated with GI side effects 1.

Clinical Presentation and Management

When ileus is suspected in a patient taking Myfortic, clinicians should:

1. Recognize warning signs:

   • Abdominal distention
   • Absence of bowel sounds
   • Nausea and vomiting
   • Constipation
   • Abdominal pain

2. Perform appropriate diagnostics:

   • Abdominal imaging (X-ray, CT scan)
   • Laboratory tests to rule out other causes

3. Management options:

   • Consider temporary discontinuation of Myfortic
   • Provide supportive care (nasogastric decompression, IV fluids)
   • Monitor closely for resolution
   • Consider alternative immunosuppression if necessary

Special Considerations

In transplant patients, any medication change must be carefully balanced against the risk of organ rejection. The British Thoracic Society guidelines note that GI side effects from similar medications may be ameliorated by dose reduction, though this may also reduce clinical efficacy 1.

Case reports have documented severe GI complications with Myfortic, including colitis 5, which further supports the potential for this medication to cause significant gastrointestinal disturbances including ileus.

Prevention Strategies

For patients requiring Myfortic who are at risk for ileus:

1. Monitor for early signs of decreased GI motility
2. Consider prophylactic measures for constipation
3. Avoid concomitant medications that further slow GI motility (e.g., opioids, anticholinergics) 6
4. Ensure adequate hydration and fiber intake
5. Consider prokinetic agents if appropriate

In conclusion, while Myfortic was designed to reduce GI side effects compared to earlier formulations of mycophenolic acid, it still carries a risk of causing ileus and other serious gastrointestinal complications. Clinicians should remain vigilant for these potential adverse effects in patients taking this medication.