What are the treatment options for severe constipation in an outpatient setting?

Treatment Options for Severe Constipation in Outpatient Setting

For severe constipation in outpatient settings, a stepwise approach beginning with osmotic laxatives and progressing to stimulant laxatives, with the addition of newer agents for refractory cases, is recommended. 1, 2

Initial Assessment and Management

• Rule out impaction through digital rectal examination and check for obstruction with physical examination (consider abdominal x-ray if symptoms are severe) 2
• Evaluate for other causes of constipation such as hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus, or medication side effects 2
• Review and discontinue any non-essential constipating medications 1, 2
• Increase fluid intake and dietary fiber if patient has adequate fluid intake and physical activity 1, 3
• Encourage exercise if appropriate for the patient 1, 4

First-Line Pharmacologic Treatment

• Start with osmotic laxatives:

  • Polyethylene glycol (PEG/Miralax): 1 capful in 8 oz water twice daily 1, 2
  • Lactulose: 30-60 mL daily to twice daily 1
  • Magnesium salts (hydroxide or citrate): 30-60 mL daily to twice daily 1
  • Note: Avoid sodium-containing laxatives as they may cause fluid retention 1

• Add stimulant laxatives if osmotic laxatives alone are insufficient:

  • Bisacodyl: 10-15 mg daily to three times daily with goal of one non-forced bowel movement every 1-2 days 1, 2
  • Senna: 2-3 tablets twice to three times daily 1
  • Note: Despite historical concerns, there is no clinical evidence that long-term use of stimulant laxatives damages intestinal muscle or neurons 1

Second-Line Treatment for Persistent Constipation

• Rectal interventions if oral medications fail:

  • Glycerin or bisacodyl suppositories: one rectally daily to twice daily 1, 2
  • Phosphate or tap water enemas until clear 1, 2

• For opioid-induced constipation:

  • Methylnaltrexone: 0.15 mg/kg subcutaneously every other day (not for post-operative ileus or mechanical bowel obstruction) 1
  • Naloxegol: oral peripheral mu-opioid receptor antagonist 1

Third-Line Treatment for Refractory Constipation

• Secretagogues for patients who fail standard treatments:

  • Linaclotide: FDA-approved for chronic idiopathic constipation, works by increasing intestinal fluid secretion and accelerating transit 1, 5
  • Plecanatide: similar mechanism to linaclotide 1

• Prokinetic agents:

  • Prucalopride: selective 5-HT4 receptor agonist for chronic constipation when other laxatives fail 1
  • Metoclopramide: 10-20 mg orally four times daily, particularly if gastroparesis is suspected 1, 2

Special Considerations

• For severe impaction:

  • Perform manual disimpaction following pre-medication with analgesic and/or anxiolytic 1
  • Be aware that diarrhea accompanying constipation may indicate overflow around impaction 1, 2

• For chronic, refractory constipation:

  • Consider referral for specialized testing (colonic transit studies, anorectal manometry) 2, 4
  • Biofeedback therapy may be effective for dyssynergic defecation 4, 6

Follow-up

• Reassess within 24-48 hours to determine response to therapy 2
• If constipation resolves, continue maintenance therapy with the effective regimen, then consider tapering 2
• If symptoms persist despite escalation of therapy, consider specialized gastroenterology consultation 2, 4

Common Pitfalls to Avoid

• Failing to rule out impaction or obstruction before aggressive laxative use 1, 2
• Using sodium-containing laxatives in patients at risk for fluid retention 1
• Inadequate dosing or premature discontinuation of laxatives 2, 4
• Not addressing underlying medication causes of constipation 1, 2
• Relying solely on fiber supplementation for severe constipation without adequate fluid intake 1, 3