What are the treatment options for constipation?

Treatment Options for Constipation

For most patients with constipation, a stepwise approach beginning with lifestyle modifications, followed by osmotic laxatives such as polyethylene glycol (PEG), and then stimulant laxatives for short-term or rescue therapy is recommended. 1

Initial Assessment and Causes

Constipation affects approximately 50% of patients with advanced cancer and most patients treated with opioids 2. Common causes include:

• Medications (opioids, antacids, anticholinergics, antidepressants, antispasmodics, phenothiazines, haloperidol, antiemetics)
• Medical conditions (hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus)
• Impaction or obstruction
• Inadequate fluid and fiber intake
• Decreased physical activity

First-Line Treatment Options

Lifestyle Modifications

• Increased fluid intake
• Increased physical activity (even bed to chair if mobility is limited)
• Ensuring privacy and comfort for defecation
• Proper positioning (using a footstool to assist with defecation)
• Abdominal massage (particularly helpful for patients with neurogenic problems) 2

Dietary Modifications

• Increased dietary fiber (25 g/day) for simple constipation 2
• Caution: Added dietary fiber should only be considered for patients with adequate fluid intake 2
• Avoid bulk laxatives such as psyllium for opioid-induced constipation 2

Pharmacological Management

Osmotic Laxatives (First-Line)

• Polyethylene glycol (PEG): 17-34g daily - most effective due to minimal effect on electrolytes 1
• Lactulose: 30-60 mL daily
• Magnesium hydroxide: 30-60 mL daily (use with caution in renal impairment) 2
• Magnesium citrate

Stimulant Laxatives (Short-Term or Rescue Therapy)

• Senna: 2 tablets every morning; maximum 8-12 tablets per day 2
• Bisacodyl: 10-15 mg, 2-3 times daily with goal of one non-forced bowel movement every 1-2 days 2
• Cascara
• Sodium picosulfate

For Opioid-Induced Constipation (OIC)

• Prophylactic treatment with stimulant laxatives is recommended when opioids are initiated 2
• If standard laxatives fail:
  • Methylnaltrexone: 0.15 mg/kg subcutaneously every other day (no more than once daily) 2, 1
  • Naloxegol: oral alternative to methylnaltrexone 1
  • Other peripherally acting μ-opioid receptor antagonists (PAMORAs) 2

For Persistent Constipation

• Combination therapy may be needed
• Consider adding prokinetic agents like metoclopramide if gastroparesis is suspected 2
• Newer agents for specific conditions:
  • Linaclotide: FDA-approved for IBS-C and chronic idiopathic constipation 3
  • Lubiprostone: effective for opioid-induced constipation in patients with chronic non-cancer pain 2

Management of Complications

For Fecal Impaction

• Glycerin suppositories
• Manual disimpaction if necessary 2
• Rectal bisacodyl once daily 2
• Enemas (contraindicated in neutropenia, thrombocytopenia, paralytic ileus, intestinal obstruction, recent colorectal surgery, severe colitis) 2

Special Populations

Elderly Patients

• Ensure access to toilets, especially with decreased mobility
• Optimize toileting (attempt defecation twice daily, 30 minutes after meals)
• PEG (17 g/day) offers efficacious and tolerable solution with good safety profile
• Avoid liquid paraffin for bed-bound patients due to risk of aspiration 2

Cancer Patients

• Discontinue any non-essential constipating medications
• Increase fluid intake and physical activity when appropriate 2
• For opioid-induced constipation, prophylactic treatment with stimulant laxatives is essential 2

Treatment Algorithm

1. Start with lifestyle and dietary modifications

   • Increase fluid intake, physical activity, and dietary fiber (if appropriate)

2. If constipation persists, add osmotic laxatives

   • PEG (first choice): 17-34g daily
   • Alternative: lactulose, magnesium salts

3. For inadequate response, add stimulant laxatives

   • Bisacodyl: 10-15 mg, 2-3 times daily
   • Senna: 2 tablets every morning (up to 8-12 tablets daily)

4. For opioid-induced constipation unresponsive to standard therapy

   • Methylnaltrexone: 0.15 mg/kg subcutaneously every other day
   • Naloxegol as oral alternative

5. For refractory cases

   • Consider specialized testing (anorectal manometry, colonic transit studies)
   • Combination therapy
   • Newer agents (linaclotide, lubiprostone) for specific conditions

Common Pitfalls to Avoid

• Using bulk laxatives (psyllium) for opioid-induced constipation
• Long-term use of stimulant laxatives as primary treatment strategy
• Inadequate fluid intake when increasing fiber
• Overlooking medication-induced causes of constipation
• Failing to provide prophylactic laxatives when starting opioid therapy
• Using magnesium-based laxatives in patients with renal impairment

Regular reassessment of treatment efficacy and adjustment of the regimen is essential for effective management of constipation.