What medications can be given for diarrhea related to Rituximab (rituximab) infusion?

Management of Loose Stools Related to Rituximab Infusion

Loperamide is the first-line medication for managing loose stools related to rituximab infusion, starting with 4 mg initially followed by 2 mg after each loose stool (maximum 16 mg/day). 1

Initial Management for Uncomplicated Diarrhea

For mild to moderate diarrhea without complicating factors:

• Start loperamide at an initial dose of 4 mg followed by 2 mg every 4 hours or after each loose stool, not exceeding 16 mg per day 1
• Provide oral hydration and electrolyte replacement 1
• Implement dietary modifications including a bland/BRAT diet (Bananas, Rice, Applesauce, Toast) and elimination of lactose-containing products 1
• Monitor for signs of dehydration or worsening symptoms 1

Loperamide works by decreasing peristalsis and fluid secretion, resulting in longer gastrointestinal transit time and increased absorption of fluids and electrolytes from the gastrointestinal tract 2. Its low oral absorption and inability to cross the blood-brain barrier minimizes central nervous system effects, making it safe for most patients 2.

Alternative First-Line Medications

If the patient is not already on opioids or loperamide is contraindicated:

• Diphenoxylate/atropine 1-2 tablets PO every 6 hours as needed, maximum 8 tablets/day 1
• Other opioids such as tincture of opium (10-15 drops in water every 3-4 hours) can be considered 1

Management for Persistent or Complicated Diarrhea

If diarrhea persists or is complicated by moderate to severe cramping, nausea, vomiting, fever, or dehydration:

• Consider anticholinergic agents:

  • Hyoscyamine 0.125 mg PO/ODT/SL every 4 hours as needed (maximum 1.5 mg/day) 1
  • Atropine 0.5-1 mg subcutaneous, IM, IV, or SL every 4-6 hours as needed 1

• For severe cases that don't respond to initial therapy:

  • Consider octreotide 100-500 mcg/day subcutaneous or IV, every 8 hours or by continuous infusion 1
  • Hospitalization may be required for IV fluid administration and close monitoring 1

Special Considerations

Rituximab-associated colitis is usually mild but can occasionally be severe 3. In a study of rituximab-associated gastrointestinal toxicity, the median time from treatment to onset was 181 days, with diarrhea being the most common symptom 3.

• For patients with fever, blood in stool, or signs of infection:

  • Consider stool evaluation for blood, Clostridium difficile, and other infectious causes 1
  • Antibiotics may be necessary if infection is suspected (fluoroquinolones or metronidazole) 1

• For severe cases with signs of colitis:

  • Endoscopic evaluation may be warranted 3
  • Immunosuppressive therapy might be required in select cases 3

Monitoring and Follow-up

• Instruct patients to record the number of stools and report symptoms of life-threatening sequelae (fever or dizziness on standing) 1
• Pay special attention to patients who are incontinent of stool due to risk of pressure ulcer formation 1
• Use skin barriers to prevent skin irritation caused by fecal material 1

Remember that loperamide takes 1-2 hours to reach its therapeutic effect, so additional dosing should be spaced accordingly to avoid rebound constipation 1.