What is the recommended bowel regimen for opioid-induced constipation?

Management of Opioid-Induced Constipation

The first-line treatment for opioid-induced constipation should be prophylactic stimulant laxatives with or without stool softeners, along with lifestyle modifications including adequate fluid intake and exercise. 1

Understanding Opioid-Induced Constipation (OIC)

Opioid-induced constipation is a nearly universal side effect of opioid therapy that, unlike other opioid side effects, does not improve over time. It is defined as new or worsening symptoms of constipation when initiating, changing, or increasing opioid therapy, characterized by:

• Reduced bowel movement frequency
• Straining during defecation
• Hard or lumpy stools
• Sensation of incomplete evacuation
• Sensation of anorectal obstruction
• Need for manual maneuvers to facilitate defecation

Preventive Approach

First-Line Prophylactic Measures:

• Stimulant laxatives: Sennosides (senna), 2 tablets every morning; maximum 8-12 tablets per day 1
• Polyethylene glycol (PEG): A heaping tablespoon (17g) with 8 oz of water twice daily 1
• Increase laxative dose when increasing opioid dose 1
• Maintain adequate fluid intake 1
• Exercise if feasible 1

Important Note:

• Fiber supplements such as psyllium (Metamucil) are not recommended for OIC as they are ineffective and may worsen constipation 1, 2
• Docusate (stool softener) alone has not shown benefit and is not recommended 1

Stepwise Management Algorithm

Step 1: When constipation develops despite prophylaxis

• Assess for cause and severity of constipation
• Rule out bowel obstruction
• Treat other contributing causes
• Titrate laxatives with goal of one non-forced bowel movement every 1-2 days 1
• Consider co-analgesics to allow reduction of opioid dose 1

Step 2: If constipation persists

• Reassess for causes and rule out bowel obstruction
• Check for impaction
• Add or switch to other agents:
  • Magnesium hydroxide: 30-60 mL daily
  • Bisacodyl: 2-3 tablets PO daily or suppository daily
  • Lactulose: 30-60 mL daily
  • Sorbitol: 30 mL every 2 hours × 3, then as needed
  • Magnesium citrate
  • Polyethylene glycol: Capful/8 oz water PO daily 1
• Consider using a prokinetic agent (e.g., metoclopramide 10-20 mg PO daily) 1
• Consider opioid rotation to fentanyl or methadone 1

Step 3: For refractory OIC

• Peripherally acting μ-opioid receptor antagonists (PAMORAs) are recommended:
  • Naldemedine (strong recommendation, high-quality evidence) 1
  • Naloxegol (strong recommendation, moderate-quality evidence) 1
  • Methylnaltrexone 0.15 mg/kg subcutaneously (conditional recommendation, low-quality evidence) 1
• These agents block μ-opioid receptors in the gut without affecting central analgesia 1
• Do not use in patients with known or suspected mechanical bowel obstruction 1, 3

Step 4: Additional options for persistent OIC

• Lubiprostone (a chloride channel activator) for OIC in adult patients with chronic non-cancer pain 3
• Consider neuraxial analgesics or neuroablative techniques to reduce opioid dose 1
• Enemas (Fleet, saline, or tap water) may be used cautiously, but avoid in patients with neutropenia or thrombocytopenia 1

Special Considerations

• Patients on chronic opioid therapy should be evaluated for appropriate indication and minimum necessary dose 1
• Vigilance is needed regarding potential drug interactions and opioid side effects 1
• Healthcare utilization and costs are higher in patients with OIC, with annual median incremental cost increases of approximately $4000 1
• Patients should be monitored regularly for response to treatment and need for escalation of therapy

By following this algorithmic approach to OIC management, clinicians can effectively prevent and treat this common and troublesome side effect of opioid therapy, improving patient comfort and quality of life.