What are the recommended medications for treating constipation in older adults?

Medication for Constipation in Older Adults

Polyethylene glycol (PEG) 17 g/day is the recommended first-line medication for constipation in elderly patients due to its superior efficacy and excellent safety profile, particularly in those with cardiac and renal comorbidities. 1, 2

First-Line Pharmacological Treatment

• PEG 17 g daily should be initiated as the primary laxative agent for older adults with constipation 1, 2
• PEG demonstrates better efficacy than lactulose (1.3 vs 0.9 bowel movements per day, P=0.005) and has minimal risk of electrolyte disturbances 3
• This recommendation is particularly strong for elderly patients with heart failure or chronic kidney disease who require diuretics or cardiac glycosides, as PEG avoids the dehydration and electrolyte imbalance risks associated with other laxative classes 1

Second-Line Options

If PEG is ineffective or not tolerated, proceed sequentially:

• Osmotic laxatives (lactulose) are the next preferred option, producing 0.7 bowel movements per day versus 0.5 with placebo (P<0.02) 3, 4
• Stimulant laxatives (senna, bisacodyl, sodium picosulfate) can be used but carry risk of abdominal cramping and pain 1, 2
• Senna combined with a bulking agent produces 4.5 bowel movements per week versus 2.2 with lactulose alone (P<0.001) 3

Newer Agents for Refractory Cases

• Lubiprostone (chloride channel activator) is FDA-approved for chronic idiopathic constipation in adults, producing 5.69 spontaneous bowel movements per week versus 3.46 with placebo (P=0.001) 5, 3, 6
• Linaclotide (guanylate cyclase-C agonist) is FDA-approved for chronic idiopathic constipation in adults at 145 mcg or 72 mcg daily, taken 30 minutes before meals 7
• These agents are particularly useful for recurrent fecal impaction and severe chronic constipation unresponsive to conventional laxatives 6

Critical Medications to Avoid

Bulk-forming laxatives (psyllium, methylcellulose, calcium polycarbophil):

• Contraindicated in non-ambulatory elderly patients with low fluid intake due to mechanical obstruction risk 1, 2
• While psyllium produces 9.08 bowel movements per week versus 8.29 with calcium polycarbophil (P=0.04), the obstruction risk outweighs benefits in frail elderly 3

Magnesium-containing laxatives (magnesium hydroxide, milk of magnesia):

• Use with extreme caution or avoid entirely in elderly patients, especially those with any degree of renal impairment 1, 8, 2
• Risk of life-threatening hypermagnesemia due to age-related decline in renal function 8
• These agents have not been adequately studied in older adults 1, 8

Liquid paraffin (mineral oil):

• Absolutely contraindicated in bed-bound patients and those with swallowing disorders due to aspiration lipoid pneumonia risk 1, 2

Docusate sodium (stool softeners):

• Lacks efficacy despite being the most commonly used laxative in practice 6
• Studies show no significant difference from placebo in most dosing regimens 3

Rectal Measures for Specific Situations

When oral medications fail or cannot be used:

• Isotonic (0.9%) saline enemas are the preferred rectal intervention for elderly patients 1, 9
• Sodium phosphate enemas carry significant risks of hyperphosphatemia, electrolyte disturbances, cardiac complications, and death in older adults 9
• Rectal measures are specifically indicated for: swallowing difficulties, repeated fecal impaction, or failure of oral laxatives 1, 9, 2

Fecal Impaction Management

• Digital fragmentation and extraction of stool is required (assuming no perforation or bleeding) 1
• Follow disimpaction with maintenance bowel regimen to prevent recurrence 1
• Consider lubiprostone for patients with recurrent impaction 6

Opioid-Induced Constipation

• All patients on opioid analgesics should receive prophylactic laxatives unless pre-existing diarrhea is present 1
• Osmotic or stimulant laxatives are first-line; bulk laxatives are not recommended 1
• Peripherally acting mu-opioid receptor antagonists (PAMORAs) are effective for refractory opioid-induced constipation but are expensive 1, 10
• Combined opioid/naloxone formulations reduce constipation risk 1

Essential Monitoring Requirements

• Regular assessment of renal and cardiac function when using laxatives concurrently with diuretics or cardiac glycosides 1
• Calculate creatinine clearance using Cockcroft-Gault or MDRD equation rather than relying on serum creatinine alone 8
• Monitor for dehydration and electrolyte imbalances, particularly in patients with heart or kidney failure 1

Non-Pharmacological Measures (Implement Before or Alongside Medications)

• Ensure toilet access, especially for patients with decreased mobility 1, 2
• Educate patients to attempt defecation twice daily, 30 minutes after meals, straining no more than 5 minutes 1, 2
• Provide dietetic support and manage decreased food intake related to aging, anorexia, or chewing difficulties 1, 2

Common Pitfalls

• Avoid prescribing stool softeners as first-line therapy despite their popularity—they lack efficacy compared to osmotic laxatives 6
• Do not increase bulk laxatives in immobile patients even if they seem logical—the obstruction risk is real 1, 2
• Never assume normal renal function in elderly patients when considering magnesium-containing products—age-related decline is universal 8
• Individualize laxative selection based on cardiac and renal comorbidities, drug interactions, and potential adverse effects rather than using a one-size-fits-all approach 1, 2