Constipation Management

Definition and Diagnosis

• Constipation is characterized by hard/lumpy stools and reduced stool frequency (fewer than 3 spontaneous bowel movements per week), according to the Rome IV criteria 1
• Opioid-Induced Constipation (OIC) is defined as new or worsening constipation symptoms when taking opioid therapy 1

Medication Considerations

• Lactulose is primarily a non-absorbable disaccharide that works locally in the colon, according to the American Association for the Study of Liver Diseases 2
• The European Society for Medical Oncology recommends avoiding lactulose in patients with neutropenia or thrombocytopenia, paralytic ileus or intestinal obstruction, recent colorectal or gynecological surgery, recent anal or rectal trauma, or severe colitis, inflammation, or infection 3
• Magnesium-containing laxatives should be avoided due to the risk of hypermagnesemia, as suggested by the European Society for Medical Oncology 3
• The American Gastroenterological Association recommends polyethylene glycol (PEG) as the first-line pharmacological treatment for chronic constipation, with a strong recommendation and moderate certainty of evidence, increasing complete spontaneous bowel movements by approximately 2.9 per week 4
• The following treatment approach is recommended by the American Gastroenterological Association:

Treatment Approaches

• Stimulant laxatives, particularly senna, are the first-line agents for preventing and treating opioid-induced constipation, with polyethylene glycol (PEG) as an effective alternative 5
• The American Gastroenterological Association (AGA) strongly recommends laxatives as first-line agents for opioid-induced constipation with moderate quality evidence 5
• For persistent constipation despite optimized laxative therapy, consider peripherally acting μ-opioid receptor antagonists (PAMORAs) such as Naldemedine: 0.2mg daily (strong recommendation, high-quality evidence) and Naloxegol: 25mg once daily (strong recommendation, moderate-quality evidence) 5
• Methylnaltrexone: 0.15mg/kg subcutaneously every other day (conditional recommendation, low-quality evidence) 5
• Lactulose enema can be used as an alternative to oral laxatives, with a recommended dose of 300 mL lactulose mixed with 700 mL water/saline, according to the American Association for the Study of Liver Diseases 2

Lifestyle Modifications

• Optimize toileting habits: attempt defecation 30 minutes after meals, strain no more than 5 minutes, as suggested by the American Society of Clinical Oncology 3
• Increasing fluid intake, encouraging physical activity if feasible, and maintaining adequate dietary fiber intake are recommended to manage OIC 6
• Starting prophylactic laxative regimen when initiating opioid therapy, including stimulant laxative (e.g., sennosides) and maintaining adequate fluid intake, is recommended by the National Comprehensive Cancer Network 7, 6

Contraindications and Precautions

• Avoid liquid paraffin in bed-bound patients (risk of aspiration), as recommended by the American Society of Clinical Oncology 3
• Consider rectal measures (suppositories, enemas) for swallowing difficulties, as recommended by the American Society of Clinical Oncology 3
• Don't use saline laxatives (e.g., magnesium hydroxide) in elderly patients or those with renal impairment, as recommended by the American Society of Clinical Oncology 3
• Don't use enemas in patients with neutropenia, thrombocytopenia, recent colorectal surgery, or severe colitis, as recommended by the American Society of Clinical Oncology 3
• Bulk laxatives such as psyllium are not recommended for opioid-induced constipation, as stated by the American College of Gastroenterology 3
• Docusate is ineffective for constipation management in adults and is not recommended by the National Comprehensive Cancer Network (NCCN) and recent evidence 7, 4
• Fiber supplements like Metamucil are unlikely to control opioid-induced constipation, according to the National Comprehensive Cancer Network 6

Monitoring and Follow-up

• Perform anorectal testing to identify defecatory disorders (strong recommendation, high-quality evidence), as recommended by the American Gastroenterological Association 8
• The goal of therapy is to achieve one non-forced bowel movement every 1-2 days, according to the National Comprehensive Cancer Network 6, 7
• Particular attention should be paid to medication lists and comorbidities in elderly patients, who are at higher risk for severe constipation and impaction, according to the American Society of Clinical Oncology 3
• Monitoring for red flags, such as severe abdominal pain, no bowel movement for >3 days, vomiting, and signs of bowel obstruction, is crucial 9
• Weekly monitoring of bowel movement frequency and consistency, severity of muscle spasms, mental status, and psychiatric symptoms is recommended 9

Surgical Options

• Consider surgical options (only in ~5% of cases), such as total colectomy with ileorectal anastomosis for documented slow transit constipation, as recommended by the American Gastroenterological Association 8