What are the recommended medications and management strategies for constipation?

Medication Management for Constipation

For the management of constipation, polyethylene glycol (PEG) is strongly recommended as the first-line pharmacological treatment due to its proven efficacy, safety profile, and low cost. 1, 2

Initial Assessment and Non-Pharmacological Approaches

Assessment Considerations

• Evaluate for possible causes of constipation including medications, metabolic disorders, and structural issues 1
• Physical examination should include abdominal examination, perineal inspection, and digital rectal examination (DRE) 1
• Plain abdominal X-ray may be useful to assess fecal loading and exclude bowel obstruction in severe cases 1

Non-Pharmacological Management

1. Dietary Modifications

   • High-fiber diet (approximately 30g/day) 2
   • Adequate fluid intake, particularly water 1, 2
   • Focus on fruits with natural laxative effects (prunes, pears, apples) 2

2. Lifestyle Modifications

   • Increased physical activity and mobility within patient limits 1
   • Ensure privacy and comfort for defecation 1
   • Optimize toileting position (use footstool to assist with defecation) 1, 2
   • Attempt defecation 30 minutes after meals to utilize the gastrocolic reflex 1, 2
   • Abdominal massage can help reduce gastrointestinal symptoms, particularly in patients with neurogenic problems 1

Pharmacological Management Algorithm

First-Line Treatment

• Polyethylene glycol (PEG) - 17g daily mixed in 8oz water 1, 2
  • Increases stool frequency by 2-3 bowel movements per week compared to placebo 1
  • Response has been shown to be durable over 6 months 1
  • Side effects: abdominal distension, loose stool, flatulence, and nausea 1

Second-Line Options

1. Osmotic Laxatives

   • Lactulose 1, 2
   • Magnesium salts (use cautiously in renal impairment due to risk of hypermagnesemia) 1

2. Stimulant Laxatives

   • Senna 1, 2
   • Bisacodyl (best administered 30 minutes after a meal) 1, 2
   • Sodium picosulfate 1

Third-Line Options

• Prucalopride - 2mg once daily (1mg for patients with severe renal impairment) 3
  • Serotonin-4 receptor agonist indicated for chronic idiopathic constipation 3
  • Monitor for potential side effects including headache, abdominal pain, nausea, and diarrhea 3
  • Important safety warning: Monitor for suicidal ideation and behavior 3

Special Situations

Opioid-Induced Constipation (OIC)

• All patients receiving opioid analgesics should be prescribed a concomitant laxative unless contraindicated by pre-existing diarrhea 1, 2
• Preferred options:
  1. PEG as prophylactic agent (17g twice daily) 2
  2. Stimulant laxatives (senna or bisacodyl) 1, 2
  3. For refractory cases, consider peripheral opioid antagonists (methylnaltrexone) 1, 2
• Bulk laxatives such as psyllium are NOT recommended for OIC 1

Fecal Impaction

• Digital fragmentation and extraction of stool, followed by implementation of maintenance bowel regimen 1
• Suppositories and enemas are preferred first-line therapy when DRE identifies a full rectum or fecal impaction 1
• Contraindications for enemas: neutropenia, thrombocytopenia, paralytic ileus, intestinal obstruction, recent colorectal surgery, severe colitis, and undiagnosed abdominal pain 1, 2

Elderly Patients

• Ensure access to toilets, especially for those with decreased mobility 1, 2
• PEG (17g/day) offers an efficacious and tolerable solution with good safety profile 1
• Avoid liquid paraffin for bed-bound patients due to aspiration risk 1, 2
• Use saline laxatives cautiously due to risk of hypermagnesemia 1
• Non-absorbable fiber or bulk agents should be avoided in non-ambulatory patients with low fluid intake due to risk of mechanical obstruction 1

Common Pitfalls and Caveats

• Failure to recognize opioid-induced constipation and provide prophylactic treatment
• Using bulk-forming laxatives in opioid-induced constipation or in patients with inadequate fluid intake
• Not adjusting laxative regimens when increasing opioid doses
• Overlooking potential drug interactions or contraindications (especially in elderly patients with multiple comorbidities)
• Inadequate dosing or premature discontinuation of laxatives before establishing regular bowel pattern

By following this evidence-based approach to constipation management, clinicians can effectively address this common condition while minimizing complications and improving patient quality of life.