What is the recommended management approach for functional constipation in the elderly?

Management of Functional Constipation in the Elderly

Polyethylene glycol (PEG) 17 g/day is the first-line pharmacological treatment for functional constipation in elderly patients due to its superior efficacy and excellent safety profile. 1, 2

Initial Assessment and Prevention Strategies

Before initiating pharmacological therapy, implement these foundational measures:

• Ensure toilet access, particularly critical for patients with decreased mobility, as this is a primary preventable cause of constipation 1, 2
• Optimize toileting habits: Educate patients to attempt defecation twice daily, 30 minutes after meals (when the gastrocolic reflex is strongest), straining no more than 5 minutes 1, 3
• Provide dietetic support to address anorexia of aging and chewing difficulties that negatively influence stool volume and consistency 1
• Increase fluid intake to at least 1.5 liters daily 2
• Encourage physical activity within patient limitations—even minimal movement from bed to chair stimulates bowel function 1, 2

Important caveat: Lifestyle modifications alone have limited influence on constipation and should never be the sole focus of management, particularly as disease progresses and health deteriorates 1

Pharmacological Management Algorithm

First-Line Treatment: Osmotic Laxatives

PEG 17 g/day is the recommended initial pharmacological intervention 1, 3, 2:

• Offers efficacy with good tolerability in elderly patients 1
• Does not require high fluid intake like bulk-forming agents, making it ideal for frail elderly patients 2
• Has an excellent safety profile with minimal risk of electrolyte disturbances 1

Second-Line Treatment: Stimulant Laxatives

If PEG is insufficient or not tolerated, use stimulant laxatives (senna, bisacodyl, sodium picosulfate) 3, 2:

• Be cognizant of potential abdominal pain and cramping 1, 2
• Can be used intermittently when osmotic laxatives fail 4

Alternative Options

Lactulose (15-30 mL daily) can be used as an alternative osmotic laxative if PEG is not tolerated 3

Critical Medications to Avoid or Use with Extreme Caution

Absolutely Avoid:

• Bulk-forming agents (psyllium, methylcellulose, polycarbophil) in non-ambulatory patients with low fluid intake—significantly increases risk of mechanical obstruction 1, 2
• Liquid paraffin in bed-bound patients or those with swallowing disorders—risk of aspiration lipoid pneumonia 1, 2
• Sodium phosphate enemas—potential for serious adverse events including hyperphosphatemia, electrolyte disturbances, cardiac complications, and death in elderly patients 3, 5

Use with Caution:

• Saline laxatives (magnesium hydroxide) have not been adequately studied in older adults and carry risk of hypermagnesemia, particularly with age-related renal decline 1, 2
• Require regular monitoring if used concomitantly with diuretics or cardiac glycosides (risk of dehydration and electrolyte imbalances) 1, 2

Management of Fecal Impaction

When fecal impaction is present, follow this sequential approach 3:

1. Manual disimpaction through digital fragmentation and extraction of stool 3
2. Follow with enemas or suppositories to facilitate passage of remaining stool 3
3. Implement maintenance regimen with PEG 17 g/day to prevent recurrence 3

For rectal measures, use isotonic saline enemas rather than sodium phosphate preparations due to significantly lower risk of adverse events in elderly patients 1, 3, 5

When to Prefer Rectal Measures:

Enemas and suppositories become the preferred treatment choice for 1, 3, 5:

• Patients with swallowing difficulties
• Repeated fecal impaction
• Failure of oral laxatives

Special Considerations Based on Comorbidities

Cardiac and Renal Disease:

• Individualize laxative selection based on cardiac and renal comorbidities 1, 2
• Monitor closely for dehydration and electrolyte imbalances in patients with chronic kidney or heart failure, especially when using diuretics or cardiac glycosides 1, 2
• Avoid magnesium-based laxatives in renal impairment due to hypermagnesemia risk 2

Opioid-Induced Constipation:

• All patients receiving opioid analgesics should be prescribed a concomitant laxative unless contraindicated 2
• Osmotic or stimulant laxatives are generally preferred 2
• Peripherally acting mu-opioid antagonists are effective but expensive 6

Common Pitfalls to Avoid

• Do not rely on docusate (stool softeners) alone—ineffective for both prevention and treatment of constipation in the elderly 3
• Do not prescribe bulk-forming laxatives to non-ambulatory elderly patients—this significantly increases obstruction risk 1, 3, 2
• Do not use sodium phosphate enemas—serious electrolyte disturbance risk in elderly 3, 5
• Do not assume lifestyle modifications alone will suffice—pharmacological therapy is frequently required 1, 4

Monitoring and Follow-Up

• Assess response to treatment regularly and adjust as needed 2
• Monitor for complications including urinary tract obstruction, stercoral ulcers, colonic perforation, dehydration, electrolyte imbalance, renal insufficiency, and rectal bleeding 3
• Regular monitoring is essential when laxatives are used with diuretics or cardiac glycosides 1, 2