What are the treatment options for constipation?

Treatment Options for Constipation

The first-line treatment for constipation should be osmotic laxatives such as polyethylene glycol (PEG), followed by stimulant laxatives like bisacodyl or senna, with specialized agents like methylnaltrexone reserved for opioid-induced constipation that hasn't responded to standard therapy. 1

Initial Assessment

• Evaluate for potential causes including medications (especially opioids), metabolic disorders (hypercalcemia, hypokalemia, hypothyroidism, diabetes), and mechanical obstruction 2
• Perform physical examination including abdominal and rectal examination to rule out impaction or obstruction 1
• Basic investigations may include calcium levels and thyroid function if clinically indicated 1

Non-Pharmacological Management

• Increase fluid intake to maintain adequate hydration 2, 1
• Increase physical activity within patient's capabilities 1, 3
• Increase dietary fiber intake (25g/day) if fluid intake and physical activity are adequate 2, 4
• Ensure privacy and comfort for normal defecation 1
• Position optimization using a small stool to facilitate defecation 1
• Abdominal massage may help improve bowel function, particularly in patients with neurogenic issues 1

Pharmacological Management: Step-wise Approach

Step 1: First-Line Agents

• Osmotic laxatives:
  • Polyethylene glycol (PEG): Safe and effective, especially in elderly patients 1, 5
  • Lactulose: Alternative osmotic agent 2
  • Magnesium salts (hydroxide, citrate): Effective but use cautiously in renal impairment 2

Step 2: Add or Switch to Stimulant Laxatives

• Bisacodyl: 10-15 mg, 2-3 times daily 2
• Senna: Start with 2 tablets every morning (maximum 8-12 tablets per day) 2
• Goal: One non-forced bowel movement every 1-2 days 2

Step 3: For Persistent Constipation

• Combine osmotic and stimulant laxatives 2
• Consider adding glycerin suppositories for impaction 2
• Manual disimpaction may be necessary for severe impaction 2

Step 4: For Refractory Constipation

• Consider prokinetic agents (e.g., metoclopramide) if gastroparesis is suspected 2
• For opioid-induced constipation unresponsive to standard laxatives:
  • Methylnaltrexone: 0.15 mg/kg subcutaneously every other day (maximum once daily) 2, 1
  • Other peripherally acting μ-opioid receptor antagonists: naloxegol 2
• For chronic idiopathic constipation or IBS-C:
  • Lubiprostone: Activates chloride channels to enhance intestinal fluid secretion 2
  • Linaclotide: Guanylate cyclase-C receptor agonist that increases intestinal secretions 2

Special Considerations

Fiber Supplementation

• Most effective for mild constipation 6, 7
• Psyllium is particularly effective (doses >10g/day for at least 4 weeks) 8, 7
• Methylcellulose provides fiber without causing excess gas 9
• Water-insoluble fibers (cellulose, hemicellulose) are most effective for laxation 4
• May cause bloating and flatulence; introduce gradually 7, 3

Opioid-Induced Constipation

• Prevention is key - start laxatives concurrently with opioid therapy 2, 1
• Use stimulant laxatives (senna, bisacodyl) plus stool softeners 2
• For refractory cases, peripherally acting μ-opioid receptor antagonists maintain pain control while relieving constipation 2, 1

Elderly Patients

• Pay special attention to medication review, toilet access, and mobility 1
• PEG is particularly safe and effective in this population 1
• Avoid liquid paraffin in bedridden patients due to aspiration risk 1

Common Pitfalls to Avoid

• Failing to identify and address underlying causes (medications, metabolic disorders) 2
• Inadequate dosing or premature discontinuation of laxatives 1
• Relying solely on fiber supplementation for opioid-induced constipation 2, 1
• Using water-soluble fibers (pectin, gums) for constipation when water-insoluble fibers are more effective 4
• Continuing to use laxatives for more than one week without reassessment 5
• Not monitoring for electrolyte imbalances in patients with cardiac or renal insufficiency when using osmotic laxatives 1