What are the treatment options for constipation?

Treatment Options for Constipation

The first-line treatment for constipation should be a gradual increase in fiber intake (through diet and supplements) combined with an inexpensive osmotic agent such as polyethylene glycol, followed by stimulant laxatives if needed. 1

Initial Assessment and Management

Identify and Address Underlying Causes

• Discontinue medications that can cause constipation when feasible 1
• Rule out secondary causes: hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus 1
• Consider structural evaluation (colonoscopy) only if alarm symptoms present or age >50 without recent screening 1

First-Line Approaches

1. Lifestyle modifications:

   • Increase fluid intake 1
   • Increase physical activity when appropriate 1
   • Schedule toileting after meals to take advantage of gastrocolic reflex 2

2. Dietary interventions:

   • Gradually increase dietary fiber to 25g/day 1
   • Consider soluble fiber (psyllium) over insoluble fiber to minimize bloating 3
   • For Parkinson's disease patients: fermented milk with probiotics and prebiotic fiber 1

Pharmacological Management Algorithm

Step 1: Fiber and Osmotic Laxatives

• Fiber supplements: Psyllium 15g daily, gradually increased to minimize side effects 1
• Osmotic agents:
  • Polyethylene glycol (PEG) 17g daily 1
  • Milk of magnesia 1oz twice daily (avoid long-term use in elderly due to potential toxicity) 1, 2
  • Lactulose as an alternative 1

Step 2: Add Stimulant Laxatives (if Step 1 inadequate)

• Bisacodyl 10-15mg, 2-3 times daily 1
• Administer 30 minutes after meals to synergize with gastrocolonic response 1
• Goal: one non-forced bowel movement every 1-2 days 1

Step 3: Rectal Interventions (if impaction present)

• Glycerin suppositories 1
• Rectal bisacodyl 1
• Manual disimpaction if necessary 1

Step 4: Prescription Medications (for refractory cases)

• For chronic idiopathic constipation: Lubiprostone 24mcg twice daily with food 1, 4
• For opioid-induced constipation:
  • Methylnaltrexone 0.15mg/kg every other day (no more than once daily) 1
  • Lubiprostone 24mcg twice daily (except with methadone) 4
• For irritable bowel syndrome with constipation: Lubiprostone 8mcg twice daily (women only) 1, 4

Special Considerations

Opioid-Induced Constipation

• Should be anticipated and treated prophylactically with stimulant laxatives 1
• Consider peripherally acting μ-opioid receptor antagonists (methylnaltrexone) for refractory cases 1
• Avoid methylnaltrexone in patients with mechanical bowel obstruction 1

Defecatory Disorders

• Biofeedback therapy is recommended over laxatives for defecatory disorders 1
• Improves symptoms in >70% of patients with defecatory disorders 1

Hepatic Impairment Dosing Adjustments

• For moderate impairment (Child-Pugh Class B): Lubiprostone 16mcg twice daily 4
• For severe impairment (Child-Pugh Class C): Lubiprostone 8mcg twice daily 4

Common Pitfalls to Avoid

• Initiating fiber too quickly (causes bloating and gas) - increase gradually over weeks 1
• Long-term use of magnesium-based laxatives (risk of toxicity) 2
• Overlooking defecatory disorders which require biofeedback rather than laxatives 1
• Using docusate sodium alone (limited evidence for efficacy) 1
• Failure to adjust treatment for opioid-induced constipation, which often requires specific management 1, 4

By following this algorithmic approach and adjusting based on patient response, most cases of constipation can be effectively managed without resorting to invasive procedures.