Is it indicated to start laxatives for opioid-induced constipation?

Management of Opioid-Induced Constipation

Prophylactic laxatives should be started simultaneously with opioid therapy to prevent opioid-induced constipation, as patients do not develop tolerance to this side effect. 1

First-Line Approach

Preventive Measures

• Start prophylactic laxative regimen when initiating opioid therapy:
  • Stimulant laxative (e.g., sennosides) 2
  • Polyethylene glycol (PEG) 17g with 8 oz water twice daily 1
  • Maintain adequate fluid intake 2
  • Increase dietary fiber intake (but avoid supplemental medicinal fiber) 2
  • Exercise if feasible 2

Important Notes

• Increase laxative dose when increasing opioid dose 2, 1
• Docusate (stool softener) has not shown benefit and is not recommended 2, 1
• Psyllium and other bulk-forming laxatives are ineffective for opioid-induced constipation and should be avoided 2, 1
• Goal of therapy: one non-forced bowel movement every 1-2 days 2

Second-Line Approach (If Constipation Persists)

1. Reassess for cause and severity of constipation

   • Rule out bowel obstruction 2
   • Check for impaction 2

2. Add or switch to alternative agents:

   • Magnesium hydroxide (30-60 mL daily) 2
   • Bisacodyl (2-3 tablets PO daily or suppository) 2, 1
   • Lactulose (30-60 mL daily) 2, 1
   • Polyethylene glycol (increase dose if already using) 1
   • Consider adding prokinetic agent (e.g., metoclopramide 10-20 mg PO three times daily) 2, 1

3. Consider enemas if appropriate:

   • Fleet, saline, or tap water enema 2
   • Caution: Avoid enemas in patients with neutropenia, thrombocytopenia, or recent colorectal surgery 2, 1

Third-Line Approach (For Refractory Cases)

When response to laxative therapy is insufficient:

• Peripherally acting μ-opioid receptor antagonists (PAMORAs):

  • Methylnaltrexone 0.15 mg/kg subcutaneously 2, 1
  • Naloxegol (oral) - requires discontinuation of maintenance laxative therapy before starting 3
  • Naldemedine (oral) 1

• Other options:

  • Lubiprostone (for non-cancer pain) 2
  • Linaclotide (for idiopathic constipation) 2
  • Consider opioid rotation to fentanyl or methadone 2
  • Consider neuraxial analgesics or neuroablative techniques to reduce opioid dose 2

Special Considerations

• Unlike other opioid side effects, constipation typically persists throughout opioid therapy 1
• Patients receiving opioids for less than 4 weeks may be less responsive to PAMORAs like naloxegol 3
• For patients with renal insufficiency, avoid magnesium-containing laxatives 1
• Discontinue PAMORA treatment if opioid pain medication is discontinued 3
• PAMORAs are contraindicated in patients with known or suspected gastrointestinal obstruction 3

Monitoring

• Weekly monitoring of bowel movement frequency and consistency is crucial 1
• Watch for red flags such as severe abdominal pain, no bowel movement for >3 days, vomiting, and signs of bowel obstruction 1

The management of opioid-induced constipation requires proactive intervention and ongoing assessment, as this side effect does not improve with time like other opioid-related adverse effects.