What are the treatment options for constipation in a general adult population?

Treatment of Constipation in Adults

Start with polyethylene glycol (PEG) 17g dissolved in 8 ounces of liquid once daily as first-line pharmacological treatment for chronic constipation in adults. 1, 2

First-Line Pharmacological Treatment

Polyethylene glycol (PEG) receives the strongest recommendation from the 2023 AGA-ACG guidelines and should be your initial pharmacological choice. 1, 2

• PEG increases complete spontaneous bowel movements by approximately 2.9 per week compared to placebo, with durable response maintained over 6 months. 2
• Dose: 17g dissolved in 8 ounces of liquid once daily. 2
• Common side effects include abdominal distension, loose stool, flatulence, and nausea, which are generally well-tolerated. 3
• Do not use docusate sodium - it has not shown benefit and is not recommended based on available literature. 1

Essential Lifestyle Modifications (Concurrent with Pharmacotherapy)

• Ensure at least 1.5 liters of water daily, increased during exercise, hot weather, or illness. 2
• Establish regular toilet attempts 30 minutes after meals to utilize the gastrocolic reflex. 2
• Use a small footstool to elevate knees above hips during defecation to assist gravity and reduce straining. 2
• Increase mobility within patient limits, even bed-to-chair transfers. 2
• Avoid supplemental fiber (psyllium) as it is ineffective and may worsen constipation - though maintaining adequate dietary fiber intake is recommended. 1

Second-Line Options (If PEG Inadequate After 4-6 Weeks)

Stimulant laxatives receive strong recommendations and can be added or substituted:

• Sodium picosulfate - strong recommendation. 1, 2
• Bisacodyl - strong recommendation for short-term use (≤4 weeks) or rescue therapy; available as tablets or suppositories. 1, 3
• Senna - conditional recommendation; start low and titrate. 1, 3

Osmotic laxatives as alternatives:

• Lactulose - conditional recommendation. 1
• Magnesium oxide - conditional recommendation, but contraindicated if creatinine clearance <20 mL/min due to hypermagnesemia risk. 2, 3

Third-Line: Prescription Agents (If OTC Agents Fail)

Secretagogues receive strong recommendations:

• Linaclotide 145 mcg or 290 mcg orally once daily on empty stomach, 30 minutes before meals - strong recommendation. 1, 2, 3
• Plecanatide - strong recommendation as alternative secretagogue with similar mechanism to linaclotide. 1, 2, 3

Prokinetic agent:

• Prucalopride (serotonin type 4 agonist) - strong recommendation, works through different mechanism than osmotic/stimulant laxatives. 1, 2, 3

Alternative prescription agent:

• Lubiprostone - conditional recommendation. 1, 2

Special Population: Opioid-Induced Constipation

All patients on opioids should receive prophylactic bowel regimen unless pre-existing diarrhea exists. 2

• First-line prophylaxis: Stimulant laxative (sennosides) OR PEG 17g with 8 oz water twice daily. 1
• Avoid docusate - adding it to sennosides is less effective than sennosides alone. 1
• Avoid bulk laxatives (psyllium) for opioid-induced constipation. 2
• Goal: one non-forced bowel movement every 1-2 days. 1

If constipation persists despite laxatives:

• Rule out bowel obstruction and hypercalcemia. 1
• Add magnesium-based products, bisacodyl, or osmotic laxatives (sorbitol, lactulose, PEG). 1
• Consider opioid rotation to fentanyl or methadone. 1

Refractory opioid-induced constipation:

• Methylnaltrexone 0.15 mg/kg subcutaneously - peripherally acting mu-opioid receptor antagonist. 1, 2
• Naloxegol or naldemedine are alternatives. 1
• These agents will not work and should not be used if mechanical bowel obstruction is present. 1

Management of Fecal Impaction

• Suppositories and enemas are first-line when digital rectal exam identifies full rectum or impaction. 2
• Enemas with sodium phosphate, saline, or tap water dilate the bowel, stimulate peristalsis, and lubricate stool. 1
• Use enemas sparingly with awareness of possible electrolyte abnormalities. 1
• Avoid rectal suppositories or enemas in patients with neutropenia or thrombocytopenia. 1
• Sodium phosphate products should be limited to maximum once daily in patients at risk for renal dysfunction. 1
• Digital fragmentation and extraction followed by maintenance bowel regimen. 2

Critical Safety Considerations

• Elderly patients (≥65 years): PEG 17g daily is preferred due to efficacy and excellent safety profile. 2
• Avoid liquid paraffin in bed-bound patients or those with swallowing disorders due to aspiration lipoid pneumonia risk. 2
• Sodium picosulfate increases risk of hyponatremia in elderly (absolute risk increase 0.05%). 3
• Stop PEG and consult physician if rectal bleeding, worsening nausea/bloating/cramping/abdominal pain, diarrhea, or need for laxative >1 week. 4

When to Pursue Further Evaluation

• Severe symptoms, sudden changes in bowel movement frequency/consistency, blood in stool. 2
• Failure to respond to adequate trial of PEG (4-6 weeks) plus prescription secretagogue. 3
• Consider anorectal manometry to assess for dyssynergic defecation - biofeedback therapy improves symptoms in >70% of patients with pelvic floor dysfunction. 2, 5
• Assess colonic transit time if medical treatment fails. 5