What are the recommended treatment options for a patient experiencing constipation?

Treatment of Constipation

Start with polyethylene glycol (PEG) 17g once daily combined with a stimulant laxative (senna or bisacodyl 10-15mg, 2-3 times daily) as first-line therapy, aiming for one non-forced bowel movement every 1-2 days. 1

Initial Assessment Before Treatment

Before initiating any laxative therapy, perform these critical evaluations:

• Digital rectal examination to rule out fecal impaction 2, 1
• Rule out bowel obstruction clinically or with plain abdominal X-ray if suspected 2, 1
• Check for metabolic causes: hypercalcemia, hypokalemia, hypothyroidism, and diabetes mellitus 2, 1
• Review and discontinue constipating medications when feasible 1
• Complete blood count is the only routine laboratory test recommended 1

First-Line Pharmacological Treatment

You have three equally effective options for initial therapy:

• Polyethylene glycol (PEG) 17g once daily - preferred by the American Gastroenterological Association 1
• Stimulant laxatives: senna or bisacodyl 10-15mg, 2-3 times daily - particularly effective for opioid-induced constipation 2, 1
• Milk of magnesia 1 oz twice daily - inexpensive alternative osmotic agent 1

All of these cost approximately $1 or less per day. 1

Lifestyle Modifications (Concurrent with Pharmacotherapy)

• Increase fluid intake to at least 2 liters daily 2, 1
• Increase physical activity and mobility within patient limits 2, 1
• Ensure privacy, comfort, and proper positioning (small footstool may help) 2
• Schedule toileting attempts 30 minutes after meals, twice daily, straining no more than 5 minutes 2

Second-Line Treatment (If Constipation Persists)

Add one of the following agents to your first-line therapy:

• Rectal bisacodyl once daily 2, 1
• Lactulose 2, 1
• Magnesium hydroxide or magnesium citrate (avoid in renal impairment due to hypermagnesemia risk) 2, 1
• Additional PEG if not already using it 1

Third-Line Treatment (If Gastroparesis Suspected)

• Add metoclopramide 10-20mg, 2-3 times daily as a prokinetic agent 2, 1

This is particularly relevant for patients on GLP-1 agonists that slow gastric emptying. 1

Fourth-Line Treatment (Refractory Cases)

For persistent constipation unresponsive to standard laxatives:

• Linaclotide - FDA-approved for chronic idiopathic constipation and IBS-C in adults, and functional constipation in pediatric patients 6-17 years 1, 3
• Lubiprostone - FDA-approved for chronic idiopathic constipation, opioid-induced constipation in chronic non-cancer pain, and IBS-C in women ≥18 years 1, 4
• Plecanatide 1

Special Considerations for Opioid-Induced Constipation

All patients receiving opioid analgesics should be prescribed a concomitant laxative prophylactically, unless contraindicated by pre-existing diarrhea. 2, 1

• Osmotic or stimulant laxatives are preferred over fiber 2
• Combined opioid/naloxone medications reduce the risk of opioid-induced constipation 2
• Methylnaltrexone 0.15 mg/kg every other day (maximum once daily) for refractory opioid-induced constipation 2

Management of Fecal Impaction

If digital rectal examination identifies impaction:

• Glycerin suppositories or manual disimpaction 2, 1
• Suppositories and enemas are first-line therapy when rectum is full or impacted 2
• Followed by maintenance bowel regimen to prevent recurrence 2

Contraindications to enemas: neutropenia, thrombocytopenia, paralytic ileus, intestinal obstruction, recent colorectal/gynecological surgery, recent anal/rectal trauma, severe colitis, toxic megacolon, undiagnosed abdominal pain, or recent pelvic radiotherapy. 2

Critical Pitfalls to Avoid

• Do NOT rely on fiber supplements alone - they are ineffective for medication-induced constipation without adequate hydration 1, 5
• Do NOT add docusate (stool softeners) to senna - evidence shows no additional benefit 1
• Do NOT use bulk laxatives like psyllium for opioid-induced constipation 2
• Do NOT use liquid paraffin in bed-bound patients or those with swallowing disorders 2
• Avoid long-term magnesium-based laxatives in renal impairment 2, 6

Special Population: Elderly Patients

• PEG 17g/day offers efficacious and tolerable solution with good safety profile 2
• Ensure access to toilets, especially with decreased mobility 2
• Manage decreased food intake that negatively influences stool volume and consistency 2
• Monitor chronic kidney/heart failure patients on diuretics or cardiac glycosides for dehydration and electrolyte imbalances 2

Special Population: Parkinson's Disease Patients

• Fermented milk containing probiotics and prebiotic fiber in addition to increased water and fiber intake 2
• Psyllium may increase bowel movements but does not improve other defecation parameters 2

Treatment Goal

Aim for one non-forced bowel movement every 1-2 days, not necessarily daily bowel movements. 2, 1