How should constipation be managed in an elderly patient, including non‑pharmacologic measures and first‑line laxatives, and taking into account dysphagia, limited chewing ability, chronic opioid use, and comorbid heart or renal failure?

Management of Constipation in Elderly Patients

Start with polyethylene glycol (PEG) 17 g daily as your first-line pharmacological treatment for elderly patients with constipation, as it offers the best safety profile even in those with heart or renal failure, dysphagia, and limited chewing ability. 1, 2

Non-Pharmacological Measures (Implement First)

Before prescribing any laxative, address these modifiable factors:

• Ensure easy toilet access, particularly critical for patients with decreased mobility—this single intervention prevents recurrence and complications 1, 2
• Optimize toileting habits: educate patients to attempt defecation twice daily, 30 minutes after meals, straining no more than 5 minutes 1, 2
• Increase fluid intake to at least 1.5 liters daily within the patient's cardiac and renal limits 2, 3
• Provide dietetic support to manage decreased food intake from anorexia of aging or chewing difficulties, which directly reduce stool volume and consistency 1
• Encourage physical activity and increased mobility as tolerated 2

First-Line Pharmacological Treatment

PEG 17 g daily is the preferred initial laxative because it has an excellent safety profile in elderly patients with cardiac and renal comorbidities, does not cause electrolyte disturbances, and works effectively even in those with dysphagia (can be mixed in liquids). 1, 2, 3, 4

Dose Escalation Algorithm

If no bowel movement occurs within 3-4 days:

1. Escalate PEG to 17 g twice daily (34 g total/day) and reassess after 3-4 days 3, 4
2. Add bisacodyl 10-15 mg daily as a stimulant laxative if PEG escalation proves insufficient after 3-4 days 2, 3, 4
3. Consider lactulose 30-60 mL twice to four times daily as an alternative osmotic agent if PEG is not tolerated 2

Special Considerations for Dysphagia and Limited Chewing

For patients with swallowing difficulties or repeated fecal impaction, rectal measures (suppositories or enemas) become the preferred treatment route. 1

• Use isotonic saline enemas (500-1000 mL) rather than sodium phosphate enemas due to fewer adverse effects in elderly patients 1, 2, 4
• Bisacodyl suppositories (one rectally daily to twice daily) can be added if oral laxatives alone are insufficient 2

Critical Safety Considerations for Heart and Renal Failure

Avoid magnesium-containing laxatives (magnesium hydroxide, magnesium citrate) entirely in patients with any degree of renal impairment due to serious hypermagnesemia risk. 1, 3, 4

Monitor regularly for dehydration and electrolyte imbalances when patients are on concomitant diuretics or cardiac glycosides, as these increase risk when combined with laxatives. 1, 4

PEG remains safe in severe chronic kidney disease because it does not cause electrolyte disturbances, unlike magnesium-based or sodium phosphate products. 4

What to Absolutely Avoid in Elderly Patients

• Bulk-forming laxatives (psyllium, methylcellulose) in non-ambulatory patients with low fluid intake—these increase mechanical obstruction risk, which is particularly dangerous in elderly patients with limited mobility 1, 3, 4
• Liquid paraffin in bed-bound patients or those with swallowing disorders—risk of aspiration lipoid pneumonia is unacceptably high 1, 3
• Sodium phosphate enemas—use isotonic saline enemas instead due to electrolyte disturbance risk 1, 2, 4
• Docusate alone—it is ineffective compared to PEG or stimulant laxatives and should only be reserved for very specific situations where other options are contraindicated 2, 3

Management of Chronic Opioid Use

All elderly patients receiving opioid analgesics should be prescribed a concomitant laxative prophylactically unless contraindicated by pre-existing diarrhea. 2

• PEG or stimulant laxatives are preferred for opioid-induced constipation 2
• Peripherally acting mu-opioid receptor antagonists (PAMORAs) may be valuable in unresolved opioid-induced constipation, though they are expensive 1

Management of Fecal Impaction

If digital rectal examination reveals fecal impaction:

• Perform manual disimpaction (digital fragmentation and extraction) after pre-medication with analgesic ± anxiolytic 1, 2
• Immediately initiate PEG 17 g/day as maintenance therapy after successful disimpaction to prevent recurrence 2
• Disimpaction should only be repeated if re-impaction occurs despite maintenance therapy, not on a scheduled basis 2

Common Pitfalls to Avoid

Do not prescribe fiber supplements to elderly patients with limited mobility or fluid intake—this is a common error that worsens obstruction risk rather than relieving constipation. 1, 3, 4

Do not use magnesium-based laxatives without confirming normal renal function—elderly patients are at high risk for hypermagnesemia even with mild renal impairment. 1, 3, 4

Do not assume constipation is a normal part of aging—systematically review medications for constipating agents and address underlying causes (hypercalcemia, hypokalemia, hypothyroidism, diabetes). 2