What is the treatment for constipation without bowel obstruction?

Treatment of Constipation Without Bowel Obstruction

For patients with constipation without bowel obstruction, a stepwise approach using stimulant laxatives as first-line therapy, followed by osmotic laxatives, and specialized agents for refractory cases is recommended. 1

Initial Assessment and Prevention

• Rule out bowel obstruction, impaction, and other treatable causes such as hypercalcemia, hypokalemia, hypothyroidism, and diabetes mellitus 1
• Discontinue any non-essential constipating medications that may be contributing to symptoms 1
• Increase fluid intake and encourage physical activity when appropriate 1
• Increase dietary fiber intake if patient has adequate fluid intake 1
• Ensure privacy and comfort for defecation; proper positioning (using a footstool may help) 1

First-Line Treatment

• Start with stimulant laxatives such as senna or bisacodyl 10-15 mg daily to TID with a goal of one non-forced bowel movement every 1-2 days 1
• Consider adding stool softeners (e.g., docusate) although evidence suggests that stimulant laxatives alone may be sufficient 1
• Increase laxative dose as needed to achieve regular bowel movements 1

Second-Line Treatment (If First-Line Fails)

• Add osmotic laxatives such as:

  • Polyethylene glycol (PEG) 17g with 8 oz water once or twice daily 1
  • Lactulose 30-60 mL BID-QID 1
  • Magnesium hydroxide 30-60 mL daily-BID (use with caution in renal impairment) 1
  • Magnesium citrate 8 oz daily 1

• For impaction:

  • Administer glycerine suppositories or mineral oil retention enema 1
  • Perform manual disimpaction if necessary (following pre-medication with analgesic/anxiolytic) 1
  • Use bisacodyl suppositories (one rectally daily-BID) 1

Third-Line Treatment (For Refractory Constipation)

• Consider adding a prokinetic agent such as metoclopramide 10-20 mg PO QID if gastroparesis is suspected 1
• For opioid-induced constipation (OIC), consider peripherally acting μ-opioid receptor antagonists:
  • Methylnaltrexone 0.15 mg/kg subcutaneously every other day (no more than once daily) 1
  • Naloxegol (for chronic non-cancer pain) 1
• For chronic idiopathic constipation, consider newer agents:
  • Lubiprostone (activates chloride channels to enhance intestinal fluid secretion) 1, 2
  • Linaclotide (guanylate cyclase-C receptor agonist that enhances intestinal secretions) 1, 3

Special Considerations

Elderly Patients

• Ensure access to toilets, especially for patients with decreased mobility 1
• Educate patients to attempt defecation at least twice a day, usually 30 minutes after meals 1
• PEG (17 g/day) is particularly safe and effective for elderly patients 1
• Avoid liquid paraffin for bed-bound patients due to risk of aspiration 1

Important Cautions

• Use magnesium salts cautiously in patients with renal impairment due to risk of hypermagnesemia 1
• Avoid bulk laxatives (e.g., psyllium/Metamucil) as primary therapy for medication-induced constipation 1
• Bulk laxatives should be avoided in non-ambulatory patients with low fluid intake due to risk of mechanical obstruction 1
• Methylnaltrexone should not be used in patients with postoperative ileus or mechanical bowel obstruction 1

Treatment Algorithm Based on Severity

1. Mild constipation:

   • Lifestyle modifications (increased fluids, activity)
   • Stimulant laxative (senna or bisacodyl) 1

2. Moderate constipation (not responding to first-line):

   • Continue stimulant laxative
   • Add osmotic laxative (PEG, lactulose) 1
   • Consider rectal therapies if stool is in rectum 1

3. Severe/refractory constipation:

   • All above measures
   • Add specialized agents (methylnaltrexone for OIC; lubiprostone or linaclotide for chronic idiopathic constipation) 1, 2, 3
   • Consider prokinetic agents 1

By following this stepwise approach and adjusting treatment based on response, most cases of constipation without bowel obstruction can be effectively managed.