What are the recommendations for using enemas and laxatives, such as polyethylene glycol (PEG) and senna, to treat constipation?

Recommendations for Enemas and Laxatives in Treating Constipation

For treating constipation, polyethylene glycol (PEG) is strongly recommended as first-line therapy due to its proven efficacy in increasing bowel movements, while stimulant laxatives like senna are recommended when stronger action is needed or for opioid-induced constipation. 1, 2

Initial Assessment and Non-Pharmacological Management

• Assess for potential causes of constipation including medications (especially opioids), decreased fluid intake, decreased mobility, and underlying medical conditions 1
• Implement preventive strategies including:
  • Ensuring privacy and comfort for defecation 1
  • Proper positioning (using a footstool to assist with defecation) 1
  • Increased fluid intake, particularly for those with low baseline fluid consumption 1
  • Increased physical activity within patient limitations 1
  • Optimized toileting schedule (attempting defecation 30 minutes after meals) 1

Pharmacological Management Algorithm

First-Line Options:

• For mild constipation:

  • Fiber supplements (psyllium) for patients with adequate fluid intake and physical activity 1
  • Note: Bulk laxatives like psyllium are NOT recommended for opioid-induced constipation 1

• For moderate constipation:

  • Polyethylene glycol (PEG) 17g daily mixed in 8 ounces of liquid 1, 3
  • PEG increases complete spontaneous bowel movements by approximately 2.9 per week compared to placebo 1
  • Side effects include abdominal distension, loose stool, flatulence, and nausea 1

• For opioid-induced constipation:

  • Prophylactic laxative therapy should be initiated when starting opioids 1
  • Osmotic laxatives (PEG) or stimulant laxatives (senna, bisacodyl) are preferred 1

Second-Line Options:

• Stimulant laxatives:

  • Senna (sennosides) - shown to be effective in multiple studies 4, 2
  • Bisacodyl (10-15 mg daily to TID) 1
  • Sodium picosulfate 1, 2
  • These work by stimulating colonic motility and reducing colonic water absorption 1

• Other osmotic laxatives:

  • Lactulose 1, 5
  • Magnesium salts (use cautiously in renal impairment) 1, 2

Management of Severe or Refractory Constipation

• For fecal impaction:

  • Suppositories and enemas are preferred first-line therapy when digital rectal examination identifies a full rectum or fecal impaction 1
  • Glycerine suppository or mineral oil retention enema 1
  • Manual disimpaction may be necessary after pre-medication with analgesics/anxiolytics 1

• For persistent constipation:

  • Consider combination therapy (e.g., PEG plus stimulant laxative) 1, 6
  • For opioid-induced constipation unresponsive to traditional laxatives, consider peripherally acting mu-opioid receptor antagonists (PAMORAs) 1
  • Methylnaltrexone 0.15 mg/kg subcutaneously every other day for opioid-induced constipation 1

Special Considerations

• Enema contraindications:

  • Neutropenia or thrombocytopenia
  • Paralytic ileus or intestinal obstruction
  • Recent colorectal or gynecological surgery
  • Recent anal or rectal trauma
  • Severe colitis, inflammation, or infection of the abdomen
  • Toxic megacolon
  • Undiagnosed abdominal pain
  • Recent pelvic radiotherapy 1

• Elderly patients:

  • Require individualized laxative regimens considering medical history, drug interactions, and potential adverse effects 1
  • Ensure access to toilets, especially for those with decreased mobility 1
  • Provide dietetic support to address decreased food intake that may affect stool volume and consistency 1

Monitoring and Follow-up

• Assess for adequate constipation symptom management with goal of one non-forced bowel movement every 1-2 days 1
• Monitor for side effects including abdominal distension, loose stool, and flatulence 1
• For persistent symptoms, reassess for impaction or obstruction (may require abdominal x-ray) 1
• Discontinue laxatives if rectal bleeding occurs or if there is failure to have a bowel movement after use 4
• Do not use laxative products for longer than one week unless directed by a healthcare provider 4