For a patient with Parkinson's disease and a history of constipation, who has recently developed worsening constipation and ileus after starting methadone, should I add sumatriptan to the current regimen of amitriptiline (Amitiza) 24 mcg twice daily and polyethylene glycol (MiraLAX) once daily to manage the dilated bowel?

Management of Methadone-Induced Ileus in Parkinson's Disease

Stop methadone immediately without tapering, continue Amitiza 24 mcg BID and MiraLAX daily, but do NOT add simethicone—instead, add a stimulant laxative like bisacodyl and consider antibiotics for bacterial overgrowth in the dilated bowel. 1, 2

Methadone Discontinuation

• Methadone does not require tapering when stopped for ileus/constipation management, as the priority is resolving the life-threatening bowel obstruction. 3
• Opioids with central action like methadone are particularly problematic in Parkinson's disease due to risk of dependence, sedation, and severe constipation. 3
• The ileus is directly caused by methadone's effect on gut motility, making immediate discontinuation essential. 3

Current Regimen Assessment

• Continue Amitiza (lubiprostone) 24 mcg BID—this chloride channel activator is evidence-based for constipation and less likely to cause diarrhea than other secretagogues. 3, 4
• Continue MiraLAX (polyethylene glycol) daily—this is first-line treatment for slow colonic transit in Parkinson's disease. 4
• However, your current regimen is insufficient for methadone-induced ileus with bowel dilation. 1, 2

What to Add (Not Simethicone)

Simethicone is NOT indicated for dilated bowel from ileus—it only reduces gas bubbles and does not address the underlying motility problem or bacterial overgrowth. 1

Instead, Add These:

1. Stimulant Laxative (Essential)

• Add bisacodyl 10-15 mg daily, titrating up to three times daily if needed. 1, 2
• Goal: one non-forced bowel movement every 1-2 days. 1, 2
• Stimulant laxatives are critical when osmotic laxatives alone fail, especially after opioid exposure. 1, 2

2. Antibiotics for Bacterial Overgrowth (High Priority)

• Dilated bowel loops are virtually guaranteed to have bacterial overgrowth, which can cause cachexia and worsen symptoms. 3
• First choice: rifaximin (if on formulary) due to non-absorbable profile and safety. 3
• Alternatives: amoxicillin-clavulanate, metronidazole, doxycycline, or ciprofloxacin in rotating 2-6 week courses. 3
• Monitor for peripheral neuropathy with metronidazole and tendonitis with ciprofloxacin. 3

3. Probiotics (Parkinson's-Specific Evidence)

• Add fermented milk containing probiotics and prebiotic fiber daily for 4 weeks. 3
• This combination increases complete bowel movements, improves stool consistency, and reduces laxative dependence in Parkinson's patients. 3

Immediate Assessment Required

• Perform digital rectal exam to rule out fecal impaction and assess pelvic floor motion. 1
• Check for obstruction through physical exam; consider abdominal x-ray given the dilated bowel. 1
• Rule out metabolic causes: hypercalcemia, hypokalemia, hypothyroidism. 1, 2

If No Response in 24-48 Hours

• Consider bisacodyl or glycerine suppository. 1
• Evaluate for manual disimpaction if impaction present. 1
• Consider adding lactulose, magnesium hydroxide, or magnesium citrate. 1
• If severe, consider tap water enema until clear. 1

Critical Pitfalls to Avoid

• Do not use stool softeners alone—they are insufficient for opioid-induced constipation and ileus. 2
• Do not ignore bacterial overgrowth in dilated bowel—this is "virtually inevitable" and requires antibiotic treatment. 3
• Do not restart opioids for pain management without aggressive prophylactic bowel regimen. 2
• Beware of overflow diarrhea—diarrhea in this context may indicate impaction, not resolution. 1

Parkinson's-Specific Considerations

• Constipation in Parkinson's disease involves both slow colonic transit AND pelvic floor dyssynergia (defecatory dysfunction). 5, 4
• This patient may have obstructed defecation requiring different management than simple slow transit. 5
• If constipation persists despite aggressive treatment, consider botulinum toxin injection into puborectalis muscle or biofeedback therapy for dyssynergia. 4

Follow-Up Timeline

• Reassess in 24-48 hours to determine response. 1
• If resolved, continue maintenance therapy with effective regimen, then taper. 1
• If persistent despite escalation, obtain gastroenterology consultation for specialized testing (colonic transit studies, anorectal manometry). 1